Ultimate Dog

By Luna Lupus - Reading Time: 14 minutes
nexgard for dogs

NexGard for Dogs: A Dangerous Gamble

NexGard for dogs is marketed as a monthly flea and tick prevention that comes in the form of a convenient chewable treat. One would assume that a product put on the market with the intent to protect dogs would never harm them, but NexGard doesn't quite fit that profile. Ever since it got approved for veterinary use, it has been catching heat from dog owners who have seen horrific adverse effects in their dogs — including death.

Most dog owners only become aware of NexGard's dark side after it's already too late for their dogs. If you are hearing about this product for the first time or swear by it as your go-to flea and tick prevention, this article sheds light on how NexGard can harm your dog and why you should feel comfortable saying no if your veterinarian suggests it. 

The active ingredient in NexGard is called afoxolaner — a pesticide from a class of chemicals called isoxazolines. Other FDA-approved products in the isoxazoline group that target ticks and fleas in pets are Bravecto and Bravecto Plus (tablets and topical solutions for cats and dogs), Credelio (tablets for cats and dogs), Simparica and Simparica Trio (tablets for dogs), and Revolution Plus (topical solutions for cats).

A Pesticide That Targets the Central Nervous System

Isoxazolines are neurotoxic; they work by targeting the insect's central nervous system, which quickly leads to death. NexGard's package insert emphasizes “selective toxicity” of isoxazolines, stating they are only toxic to insects and acarine, not mammals. And yet, almost a decade of reported adverse effects by dog owners and veterinary professionals shows a different truth. Isoxazolines are neurotoxic to more than just insects; they also affect mammals. There is a reason why so many dogs experience seizures, ataxia, and tremors after taking NexGard — the pesticide compromises the dog's central nervous system. Once this happens, there is often no way back. 

NexGard's cross-species neurotoxicity creates a dangerous gamble for dog owners who opt to give their dogs this product. One dog owner I spoke to compared it to Russian roulette. Her Sheltie, previously a healthy agility dog, started seizing after NexGard. “I talked with his breeder, and no others in his lines have had epilepsy and none since. His sire is a silver grand champion, dam grand champion, and numerous others in his lines are also champions.

So, many dogs were bred throughout his lines with no epilepsy. In fact, I know lots of dogs and owners in those lines all across the country. So, why my dog? […] Well, after reading the dangers and understanding how Nexgard works killing fleas, it made sense how it could have the same effect on my dog. From what I know from others, it's a bit like Russian roulette. It's fine until it's not, and you won't know till it's too late and there is no antidote to reverse it. The damage is done.” — Melanie and her dog Ely 

What Does NexGard's Package Insert Say? 

NexGard came on the market in 2013 and 2014. In 2018, due to consistent reports of serious adverse effects, all companies that manufacture flea and tick prevention products based on isoxazoline had to change their labels and include a clear warning about potentially irreversible side effects to the nervous system.

The package insert for NexGard says: “Afoxolaner is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions, including tremors, ataxia, and seizures. Seizures have been reported in dogs receiving isoxazoline class drugs, even in dogs without a history of seizures. Therefore, use with caution in dogs with a history of seizures or neurologic disorders. The safe use of NexGard in breeding, pregnant or lactating dogs has not been evaluated.” 

There are two sections of adverse reactions listed on the package insert. The first are the adverse reactions observed in a 90-day pre-approval study (conducted by NexGard, of course), which include vomiting (with and without blood), dry and flaky skin, diarrhea (with and without blood), lethargy, and anorexia. In addition, two dogs experienced seizures, both with a previous history of seizures.

The second section lists adverse effects most commonly reported directly by dog owners in the 4-year period after approval. “The following adverse events reported for dogs are listed in decreasing order of reporting frequency for NexGard: Vomiting, pruritus, lethargy, diarrhea (with and without blood), anorexia, seizure, hyperactivity/restlessness, panting, erythema, ataxia, dermatitis (including rash, papules), allergic reactions (including hives, swelling) and tremors.”

Notice how high on the list seizures are. They are the 6th most reported side effect!!! The most-reported one is vomiting, which is very telling. Vomiting is a natural way of purging the substance that's disrupting your dog's stomach. Throwing up the pesticide could actually protect him from the adverse effects if the pesticide is completely eliminated. The packaging insert encourages dog owners to redose the dog with a full dose if he throws up within two hours of getting NexGard — I implore you to trust the dog's natural defense system instead and never give him another dose.

What about protection from tick-borne diseases?

Don't the potential benefits of NexGard outweigh the risks? Well, according to the official product information: “Parasites need to start feeding on the host to become exposed to afoxolaner; therefore, the risk of the transmission of parasite borne diseases cannot be excluded.” NexGard can only kill fleas and ticks once they've already bitten your dog, so if a tick happens to carry a disease, it can still pass it on to your dog. NexGard doesn't keep fleas and ticks away from your dog — it just kills them once they're already feeding on your dog. It's not a repellent; it's a pesticide for existing infestation.

Adverse Effects in Official FDA Numbers 

The FDA (Food and Drug Administration) and EMA (European Medicines Agency) collect reports of adverse reactions to veterinary drugs and products they approved. The FDA issued a public warning to dog owners and veterinarians who consider using isoxazoline products.

“The FDA is alerting pet owners and veterinarians of the potential for neurologic adverse events in dogs and cats when treated with drugs that are in the isoxazoline class. […] Isoxazoline products have been associated with neurologic adverse reactions, including muscle tremors, ataxia, and seizures in some dogs and cats. Although most dogs and cats haven't had neurologic adverse reactions, seizures may occur in animals without a prior history.” 

Since NexGard doesn't include the numbers on their label, and the FDA doesn't include them directly in their warning, I think it's important to share them here, so you can understand how many dogs are hurt by these chewables. These side effects are not isolated events — they are a pattern. Between January 2013 and January 2017, the FDA found 1,728 reported seizures and 801 reported deaths caused by isoxazoline products. NexGard, specifically, was responsible for 341 of those deaths.

Vomiting was the most reported isoxazoline side effect, experienced in 13,251 dogs. It was followed by behavioral issues (9,266), skin issues (7,502), and anorexia (4,639). These numbers only cover cases in the USA that have actually been reported in the first 4 years after most isoxazoline products hit the market. Today those reported numbers are even higher. The FDA makes it very difficult to find the exact numbers, and it's only possible to find them for active ingredients in veterinary drugs, not for individual brand names.

According to their records, afoxolaner (the active ingredient in NexGard) has caused 1,261 deaths by the time of writing this article in April 2022. NexGard Spectra contains milbemycin oxime in addition to afoxolaner — this pairing is responsible for 6,455 reported deaths to date. The EMA's numbers are equally horrifying. Between January 2013 and January 2019, they recorded 6,272 reported seizures and 5,556 reported deaths caused by isoxazoline products. 

Here's my question for the FDA and EMA: how many dogs have to die for a product to be considered unsafe? If thousands of deaths are not enough, and the number is consistently rising with each passing year, I shudder to think of how many dogs have yet to lose their life because of this. How can thousands of deaths directly related to a product that advertises protection result only in adding a small warning to the label? A label that most people don't even get to read!

From Adverse Effects to Broken Hearts

Thousands of dead dogs means thousands of broken hearts, thousands of traumatized owners whose trust in veterinarians is forever compromised, thousands of people mourning losses that never should have happened! Sue, a dog owner who lost her Cavalier King Charles to seizures after NexGard, shared her story.

“I was distraught,” she says. “Phoned vets to get him seen to. I called my partner as I was a wreck. By 4:15, he started fitting again in my arms and continued fitting for 20 minutes — he was dying in my arms. He stopped fitting for 15 minutes and started fitting again in the surgery, and died in my arms. That was 6 years ago; his death has scarred me, and I still mourn his loss. […] I didn't know any better than to trust what I was being told by my vets, and I didn't know then what those pills cause. It was a couple of years later that the pieces of the puzzle came together — I gave my boy that 1 dose of poison that killed him.”

Brenda's Golden Doodle started seizing after NexGard when he was only 14 weeks old, and he passed away 7 months later. She tells me about the experience: “We tried everything, from detox to every anti-seizure medication and nothing helped. He continued to decline until he had more bad days than good. 7 months of not sleeping and hardly eating while I tried desperately to save my dog left me with what I believe is PTSD. That was almost two years ago, and I still have insomnia and anxiety. It was horrific and the worst thing I have ever gone through in my life!!” 

EMA's reports also show that over 55% of seizures and 60% of deaths occurred in dogs over the age of 5, which means that isoxazoline flea treatments can be risky even for dogs who haven't reacted to them before, but could have a reaction as the years progress. “My Brody is one of the lucky ones,” Ginger tells me about her dog, who was on NexGard his whole life before it started causing problems at 7 years old. “Once I connected his seizures to Nexgard after basically one whole year, I stopped the meds. He has been seizure-free now for 1 1/2 years.” 

Independent Study Shows Majority of NexGard Users Experience Adverse Effects 

The most recent independent study into the adverse effects of isoxazoline-based flea and tick chewables was published in 2020. The results analyze survey answers from veterinarians, pet owners, and other pet caregivers. 1,325 people reported using isoxazoline products — of those, 911 people used Bravecto (fluralaner), 342 used NexGard, and the rest used Simparica (sarolaner). 87% of those who reported using Bravecto, 69% of those who used NexGard, and 61% of Simparica users experienced an adverse reaction in their dog.

This shows, once again, that the adverse effects of isoxazoline products are not a rare exception. In fact, if you are reading this article as an avid user of these brands and haven't seen a reaction in your dog yet, chances are you are the exception.

From most common one to least common one, the reported side effects of NexGard were: lethargy and depression, loss of appetite, vomiting, diarrhea, itching, restlessness and anxiety, panting, weakness, shaking and trembling, ataxia (loss of coordination and muscle control), seizures, death, abnormal stools, excessive drinking, weight loss, hair loss, decreased water intake, excessive urination, and flatulence.

Note how seizures and death, again, rank very high. 12% of surveyed NexGard users lost their dogs! It is also interesting to see a broader range of side effects observed by dog owners than are disclosed on the package insert or even in the official FDA reports. 

If NexGard for Dogs Is Toxic, Why Do Vets Recommend It? 

NexGard and other isoxazoline products cannot be purchased without a vet's prescription, and the first dose is often given directly by the veterinarian. Most people don't question veterinarians when they prescribe a product, and why would they? A certain level of trust in their expertise is implied just by being there. I want to emphasize that I'm not attempting to take a dig at veterinarians with this commentary — they have a lot of knowledge and a ridiculously tough job that is physically and emotionally taxing.

What I am trying to do here is highlight a chink in the armor! Companies that sell isoxazoline flea and tick products have to market to veterinarians before they can market to dog owners. They need to convince vets to prescribe and recommend their product over all others. When a new product hits the market, the only information about it comes directly from the manufacturer — usually in the form of a carefully curated, elegantly worded, questionably researched, and informationally depleted package insert. 

A larger conversation is desperately needed about how much independent research veterinarians should do into the products they are routinely prescribing. One of the most significant pieces of reliable information veterinarians can get on any product is client feedback! There needs to be a level of empathy and understanding for their clients' intuition regarding their dogs. The majority of dog owners who shared their NexGard stories with me were met with doubt and denial by their veterinarians.

Nadine's Frenchie was 6 months old when he started seizing after NexGard. “Vet said it was idiopathic. Spent a lot of money running tests to see what was wrong with him. […] I asked the vet if Nexgard could be the cause and I was reassured, NO. We gave him the 2nd dose, and he had a 2-hour long seizure; it was so bad we couldn't get him in the car to get to the vet. When we arrived, he was brain dead, couldn't walk, blind and deaf. I don't think he heard us say goodbye. […] He was a five thousand dollar dog that had zero health issues, not even worms. His DNA tests were beautiful. He was the sweetest boy on the planet. I was unaware of the risks, and I trusted our vet. They lied to us, and I lost my puppy. After he died, the vet dropped us when I asked why they didn't err on the side of caution.” 

“It's been hard for him and us,” says Dimitri, whose American Cocker Spaniel is currently battling severe seizures because of NexGard. “Apart from the actual physical impact … which is a real battle, you also need to “fight” most vets, specialists — heck, even friends and family — who just keep on denying the fact these kinds of pesticides can really harm our and their companions. Reactions like “there must have been something wrong with the dog anyway, send him back, put him out of his misery,” etc. have been so common. I've no words anymore for what we've seen, heard in the last year.”

A few dog owners did tell me their veterinarians were sympathetic and reported the adverse reactions. Official FDA numbers show 33,182 veterinarians reported adverse effects of afoxolaner + milbemycin oxime (NexGard Spectra), and 8,625 veterinarians reported them for afoxolaner (NexGard). The majority of reports remain filed directly by the owners, though, which is why veterinarians must start listening to their clients, take them seriously, trust in the owners' knowledge of their dogs, diligently report all adverse effects, and stop gambling with these dangerous products. 

Finny's Legacy 

A public Facebook group with over 34 thousand members is a community of people sharing their heartbreaking experiences with isoxazoline products and discussing their natural alternatives. The group was created by Carol, whose Boxer Finny got paralyzed after his first dose of NexGard when he was 7 years old. He never fully recovered and unfortunately passed away from seizures 3 years later. This experience prompted Carol to create the group. In her own words: “I couldn't save my boy. This is why I started this FB group, hoping to help save others and their furry family members from going through the same horrors our boy endured.” 

On this note, I want to thank the dog owners who entrusted me with their heartbreaking stories. I wish I could highlight all of them in this one article; I never expected to receive so many. I dedicate this article to you and your dogs — both the warriors and the angels. 

Safe Solutions to Flea and Tick Prevention

The silver lining lies in the fact that there are so many natural ways to prevent fleas and ticks, ways that work with the dog's immune system rather than against it. 100% natural flea and tick repelling shampoos and sprays can be purchased in many pet stores or online, but you can easily make your own products as well. This article shares exactly how you can protect your dog from parasites without ever having to worry about pesticides again. 


Fact Sheet for Pet Owners and Veterinarians about Potential Adverse Events Associated with Isoxazoline Flea and Tick Products.” FDA, 13/08/2021.

Palmieri, Valerie. Dodds, W. Jean. Morgan, Judy. Carney, Elizabeth. Fritsche, A. Herbert. Jeffrey, Jaclyn. Bullock, Rowan. Kimball, P. Jon. “Survey of canine use and safety of isoxazoline parasiticides.” Veterinary Medicine and Science, 02/06/2020. 

NexGard official product information (USA) 

NexGard official product information (EMA)

OpenFDA – Animal drug adverse event reports since 1987

Luna Lupus

Luna’s passion for learning about canine psychology and behavior began when she adopted a severely reactive puppy from a local shelter. She is now a big advocate for positive reinforcement and compassionate training. As a writer, she strives to spotlight the topics that fly under the radar and be the voice for all who cannot speak for themselves.

53 thoughts on “NexGard for Dogs: A Dangerous Gamble”

  1. Thank you so much for writing this informative article. i pray it will encourage pet owners to do their own research into any products for their pets, including food, medications and parasite control. Regards Carol

    1. Excellent article! I can’t thank you enough for advocating for our precious pets against these toxic meds. I appreciate you and what you are doing to get the word out.
      All my best, Ginger and Brody

  2. Thank you for this. My boomer died from 1 dose of nexgard. 5 days before he turned 1 we took him on a hike. Volunteers warned us about ticks so as great dog owners we did the right thing and went straight to the vet on got the best flea med out there. Or we thought we did. 5 days later on his 1 year birthday the nightmare started. 3 days fighting for his life. 8 months later and horrific seizures lasting hours multiple times a day he died. It has been 3 years and I have not stopped fighting. I save 1 fur baby at a time I spread boomers story to anyone who wants to know. I will never stop. I only wish I had known what I know now thank you for this 🙏

    1. Just read your warning against nexgard,just 2 days ago I gave my rather large puppy nexgard,now I’m really worried about him ,all I can do now is pray for him , that he’ll be ok. But I’ll never give him nexgard again , and I’ll never go back to that vet again.

  3. Thank you so much for this information. It is too late for my little girl but maybe someone will see it in time. Is soon as I called the company and told them what had happened they said they would cover all my expenses, and sent me a check. I wish I could have sued them. My baby died one week to the day I gave her the only dose. Had a necropsy done and confirmed it was the Nexgard.

  4. My dog almost died from Nexgard. Following a dose, he became so ill, she was near death. She ended up with auotimmune disease and it too WEEKS- months for her to get better. DO NOT USE any of ‘these’ chewable tick/ flea meds.

    1. My dog is suffering with a suspected ideopathic auto-immune disorder and I believe it is from the Nexgard. Where can I find more information on this? Thank you.

      1. Hi Angela,

        I think the Facebook group that is linked in the article could help you. There are thousands of people in that group and you can ask if someone else had a similar experience with their dog. I’m sure they’ll point you into the right direction!

        Best of luck,


      2. I think my dog is having a reaction to Nexgard. He’s only a year and a half old and last summer (his first summer) when he took Nexgard he would pant and chew all the fur off his legs. and his entire undrecoat fell out. he was less than a year old and was balding. But I didnt suspect the Nexgard. The vet just said he had allergies, even though he was fine before his first dose of Nexgard. I discontinued it in the fall and all symptoms cleared up and his coat came back and is full and thick like a lion… He was fine all winter long and into this spring, so far. Yesterday, I gave him his first dose of Nexgard of the year and he started panting about one to two hours after ingesting it and now he’s panting like he’s on fire and he’s already chewed a patch out of his right leg. I had to wrap it, the hair is all gone and he’s bleeding! and the panting is ridiculous. He’s a big dog and the panting is loud and unrelenting. How can you flush their system of this poison? I have no doubt Nexgard is the culprit, as he was fine until he ate this chewable poison.

        1. Hi Denise,

          Because of the way NexGard works it’s not really possible to “flush the system” … other than what the dog’s system is already doing on its own. Your dog’s side effects are showing that his immune system is already reacting to NexGard. But that doesn’t mean there’s nothing you can do! Right now the most important thing is to support his immune system as it’s in the process of fighting off the toxicity. Here are some things you can do:

          1. Start by supporting your dog’s gut! The health of his gut microbiome is crucial in this fight! Probiotics are the best and fastest way to do so. We have an article on probiotics here: https://ultimatedog.com/probiotics-for-dogs-how-to-bring-a-happy-balance-to-your-dogs-gut/

          2. Support your dog’s immune system with a healthy, species-appropriate diet. If he’s eating kibble, here are some ideas how to make make it richer in important nutrients: https://ultimatedog.com/how-to-improve-your-dogs-kibble-based-diet/

          3. This article explains the gut-brain connection and includes even more recommendations on how to support brain health through gut health: https://ultimatedog.com/dog-anxiety-the-brain-gut-connection/

          Sending the absolute best wishes to your pup!


          1. Just read your warning against nexgard,just 2 days ago I gave my rather large puppy nexgard,now I’m really worried about him ,all I can do now is pray for him , that he’ll be ok. But I’ll never give him nexgard again , and I’ll never go back to that vet again.

    1. Yes it’s maddening you PAY them big $$$ to provide professional medical care and they Poison your pet!
      No integrity at all! As bad as our Government! If Vets can’t get you to come back through their clinic door … if they didn’t Create Diseases in your pet by a prescribing Toxic Insecticides … even scaring pet owners telling them “pet will get Lyme disease “! If they didn’t make your pet sick Then they couldn’t keep their doors opened! Shameful that the MAKE you pets so sick just so you’ll return with a very sick animal so they can runs test galore when
      These deceitful No goods KNOW your pets illness from the NEXGUARD they told you to give pet monthly and prescribed it to them and charged you $89.00 / box for it
      Absolutely horrific!!

  5. What is wrong here?? Why isn’t someone doing something about this !!!! My 9-1/2 yr old Pomeranian … out of no where ( she was fine and a week or so later she was lethargic , not eating , just sad ) apparently she went into liver failure ….and the vet said she was dying and not much to do …. I had scheduled a euthanasia vet to come to my house . But that evening my dog fell asleep and passed away in my arms. She was a tiny 5lb Pomeranian. I had the prescription from the vet and the flea meds were compatible w her size . I have 2 other bigger dogs in my house and they are in the bushes etc and I know fleas etc get passed so easily. I thought as a pet owner I was doing the right thing. Now I think totally differently after my dog died!!! I am devastated. Is anyone researching or doing anything about this ??

  6. My 14 yo yellow lab got her first dose of Nexgard recently. Soon after she quit eating and drinking. She has small seizures when I feed her food or water through a syringe in her mouth. I know it was the Nexgard that has done this . I am not happy with my vet and will be talking with him tomorrow about this. Thank you for posting this information.

    1. Hi Sandra, thank you for your question!

      I’ll start by saying that in this case behavioral side effects are a combination of physiological + neurological implications of isoxazoline. The most common side effect like that is anorexia (refusing to eat to the point of endangering their life).

      Many owners also reported lethargy (lack of energy, slow and unstable movements) and apathy (lack of “spark,” staring into space, seemingly drained of all life energy, not responding to the environment). Some dogs experienced the opposite effects, such as severe restlessness and the inability to settle down.

  7. Thank you for writing this… I hope more pet owners become aware of the dangers of giving their pets these medications but often it’s only after an adverse reaction occurs, like in my case. And even then, when you do tell other pet owners about the dangers, they assume their pets are safe because nothing has happened yet. I was just speaking to an acquaintance about our experience with Nexgard, and she (her dog takes Simparica) thought these medications were anti-virals, and was in disbelief when I said, “no, these are pesticides”.
    My experience with Nexgard: I gave my 7-month old Wheaten puppy Nexgard on the advice of my vet, and within 24 hours she had tremors and ataxia. That first tremor lasted 10 hours. I immediately connected her reaction to Nexgard and spoke with my vet at the time who said there was no way to confirm that. And yet, I found that neurological side effects are indeed part of this medication’s repertoire. Needless to say, I have never given her another does of any tick, flea or heartworm medication, oral or otherwise. That was seven months ago, and our pup still has the occasional tremor. My current vet thinks it’s possible it’s still working its way through her system and that she may grow out of it as her nervous system matures. I’m hoping it is just a matter of time. She comes from a reputable breeder (30 years) and a very healthy breed line (health-tested) and all of her siblings are fine. It really is like Russian roulette when you give your pets these tick and flea medications.

    1. All of these insecticides affect our dogs but since most of us DO NOT even look for a reaction & dont think it could possibly be from a drug prescribed by our Vets!
      We’re in denial FOR CERTAIN!
      So we do not document the dogs reactions
      Or we think our pet is being dramatic and do not recognize our dog is trying to tell us they are being poisoned when they vomit! we ARE poisoning them Right in front of our STUPID faces!
      And then wonder what happened to our healthy pet !!?!

  8. Thank you much for this information but it was too late for myStella as she passed away 1/6/23 in my arms it started out with her gaining lots of weight 80 lbs for a border collie who was very active then hair falling out eyes looks funny then vomiting shakes finally death she was just 5 years old never again will I ever give this poison. Heart breaking to watch a loving animal suffer

    1. My dog has recently been diagnosed with tick borne illness been on nexgard for awhile somehow makes you wonder do these meds do anything they’re supposed too?

  9. My border collie had all of these symptoms. Itchy skin, seizures, couldn’t walk sometimes, wouldn’t lie down. I had taken him to the vet several times, she couldn’t figure out what was wrong. He was getting so bad, and we had another appt, that was scheduled 2 weeks out. I was pissed it was so far away. Well, had a really bad night one night, I called them as soon as they opened the next day and said he can’t wait until Friday. I need to bring him in now!!!! They said, we have a cancellation for 11. I paced waiting for the time to leave. It had snowed the night before, so before I went out to remove snow from windshield and warm up the car for him, I told him “hang on buddy, just a few more minutes.” When I came back inside, he was gone. On my bedroom floor. I took him to the vet and told them I wanted an autopsy (before he was cremated), I wanted to know what was wrong with him. I said I had videos and notes a mile long of his symptoms and behaviors. They gave me a card with an email address to send them to if the vet wanted them and told me she would be reaching out. Never heard from them again, except to pick up his ashes. I sent an email directly to the vet regarding my disappointment and never heard anything. This was Jan 2021. I was with them for 30 years. Needless to say I found a new vet for my other dog. Who went through 9 months of mourning losing her brother, wouldn’t eat, wouldn’t play, lost 13 lbs. When she was doing better, we got her a new ACD puppy brother. But 7 weeks later, she was hit by a car 5/2022, now we just have the pup. And he will not take the Nexgard. Even if I wrap it up in something yummy, he chews it up and spits out the Nexgard. So I started grating it into his food (which is homemade by the way). I’m trying to take such good care of this guy, but he obviously knows something I don’t. The Nexgard is poison and that’s why he won’t eat it. Time to find a natural alternative. I can’t lose another dog.

  10. Our vet, who we have known for nearly 30 years and trust, saw our Border Collie a few months back and said she was “infested with fleas” Somehow, my husband believed this though she wasn’t. If she was,the cat that lives with her would be infested too. Neither are, or ever were, and I am fully aware of what a flea infestation looks like. So, we are sold a very expensive two boxes of this stuff, the Nex Gard – now I do the heartworm – am religious with that – but this was a first. Well, out of nowhere, the dog falls ill. Somewhat paralyzed. She is back, but stumbled like a drunk. Then, all of a sudden, her coat started shedding like there was no tomorrow. My husband thought for a while, said the only different thing has been that nexGard. Well, of course, while she was at the vet for NEARLY A MONTH she didn’t get any of this junk and we didn’t give it to her here anymore. Well, she is coming back and is nearly 100% as far as walking, and her coat has grown back. Now, I am going to contact NexGard and tell them what happened and I want a refund. I am stuck with a box and a few tabs. People wonder why their pets get sick; same reason we do. Overmedication.

  11. We gave our boarder collie his treatment three days ago first he did not want to eat it period first flag,Second he just wants to sleep and not eat, Third this is the second dose he did not want to eat this year and we forced and I feel horrible for doing this,He was telling us this pill is making him sick please do not give it to me.After this dose I started reading and found this great article,Thank you for posting and to all the fur babies owners that have lost and love their dogs for the reviews, All dogs are smart they have a keen sense of smell and are able to communicate with us in so many ways that certain things are just not right for them,I am listening now after seeing how he has reacted to this medicine for the second time. NO MORE! Im sorry for all your losses and to those that ae suffering from this medicine,We are looking into all natural.

  12. Thank you for sharing your stories. My German Wirehair Pointer is 9 years old, has skin allergies and can get anxious easily. After allergy issues with the topical flea treatments. And a household flea issue last fall. My vet recommended Next Guard. I was about to give her the first dose and decided to look online. I am glad I found your comments. The package insert makes the serve side effects seem rare. I think I will work harder at more natural flea and tick remedies.

  13. I just lost my 2 yr old aussiedoodle. She started having seizures 3 months after starting Nexguard. I initially didn’t associate the seizures with Nexguard until after our groomer mentioned it to us. I stopped giving her the Nexguard. She was put on phenobarbital initially which worked for a couple of months. She then had a really bad seizure requiring us to take her to the Vet ER. They added Keppra and she seem to do well for two months. Two nights ago she started to have a seizure around 10 pm. At first, i wasn’t too concern because i thought it would be a mild one that will only last a couple of minutes similar to one she had 5 weeks earlier. Unfortunately, it wasn’t. After a couple of minutes, she seemed to be coming out of it, but then would start again. We took her immediately to the Vet ER. Upon arrival, she was still seizing causing her temp to rise to 105 degrees and her brain to swell. At 5 am, they thought they had her seizure under control but will watch her a few hours. Her prospect for full recovery looked good. Unfortunately, the seizures began again. She did have two more seizures and at one time was unresponsive. They called back and recommended we come in. When we returned, we were told that she had irreversible damage to her motor functions. She could still walk and wag her tail when we were there. However, she walked aimlessly bumping into walls and furniture. I thought there was still hope. But there wasn’t. The doctor, who was very kind, explained that her condition was very serious. They did not have the seizures under control. If they continued to try to control her seizures with additional medication, the medications will only harm her more and prolong the inevitable. Se will either die from the seizures or the medication. With heavy hearts, we agreed to have her put to sleep. I know seizures can be idiopathic and excepted that initially. However. I really believe it was Nexguard. Now, like so many, I have to accept the fact that I may be the one that killed my little girl. Never again.

    1. Hi Deborah,

      First I want to say that I am so, so deeply sorry for your loss. What you went through is heartbreaking. I understand that guilt is sometimes part of the grieving process, but please don’t blame yourself for what happened. There is no way you could have known … you trusted the advice you got from a veterinary professional. Even veterinarians sometimes don’t know … they just trust their drug suppliers. It’s a vicious cycle, a dark rabbit hole …. one we only realize exists when something painful happens … when something goes wrong.

      There is no doubt in my mind that your precious dog knows how loved she was by you & how you fought for her LIFE until the very last second. You carry no blame in what happened! The careless, irresponsible, money-grabbing drug company does! Don’t put on yourself the blame that belongs to THEM, please.

      I know your pain is still so raw … I admire your strength to share your story with us just 2 days after you said goodbye. I’m sending you a tight hug & praying for your journey through this grief. Be kind to yourself. You did all you could.

      All my love,


  14. I’m finding more and more articles that say the same thing as this one so I took my dog off Nexgard last fall. I feel so conflicted though about what is the right thing because I want to protect him better and we live in a highly tick infested area. A lot of natural alternatives don’t seem to work here in the woods of Maine. Ticks have become more prevalent even in the winter with the warmer weather we’ve been having. I’d love more suggestions about solid alternatives to the super toxic stuff!

    1. I’ve noticed you haven’t gotten any replies to your post.

      We have two livestock guardian dogs who protect our sheep while they are out on pasture. Obviously the idea of keeping them in tick free areas is not a starter. Over the years we have tried everything we could find anywhere as have other people in our area. We’ve had tick seasons where we have literally filled mason jars with ticks soaked in isopropyl alcohol. Last year we gave in and gave them NexGard, tick problems ended and so far (fingers crossed) no side effects that I’m aware of. I hate and I do mean hate giving my dogs something that could have the adverse reactions afoxolaner can cause. However what I hate even worse is picking tens of ticks off my girls every day knowing that even more have successfully fed and were able to create more ticks.

      So I’m with you, I would love any viable alternative that will keep the ticks off my girls. Until then I guess I keep rolling the dice and hope I stay lucky, helluva choice.

  15. DEAR LUNA,
    Your reply to DEBORAH Was Exactly Heartfelt and true, My dog had a seizure (awful) after one week giving him Nexguard. I feel quite responsible about what I did to him. Your response to Deborah relieved me of guilt, somewhat. Thanks for your response. My dog has not died, I am hopeful he is okay for the remainder of his life. Koda is 12 years old and a boykin spaniel.
    Thanks, Debby

  16. We have a 12 week old lab, my wife gave him nexgard today even though i was against it. I definitely notice he is alot more sleepy than usual. Hopefully this is the only reaction he has to this. My wife tried to give it to him and he spit it out numerous times, she then mixed it in with his food and when he was done it was still sitting in the bowl, but she finally got him to eat it. Now i am reading these comments and it has me worried! He is definitely lethargic and sleepy!

  17. Hi. Sorry for everyone’s losses, I am heartbroken reading these sad stories. My White Shepherd is almost 10 years old, he’s always been on Drontal & touch wood has had no issues. I was going to change to Nexgard Spectra as I have noticed him suddenly nibble at himself….flea? Plus Drontal are huge tablets even when cut in half & he cunningly will spit them out after eating the meat all around them. And because he is around 45kgs he needs 1 & 1/2 tablets = 3, getting harder to give as he gets older & wiser. We don’t have a tick problem in NZ & fleas don’t seem to be problematic but I never want him to get worms. After reading these reviews I’m just going to stick with Drontal for worms. Thank you for your article.

  18. One week ago today, we had to euthanize Molly, our beautiful Cavalier King Charles, who was 11 years old. She received her second Nexgard on July 1 and on July 3, she started to vomit profusely, and she never ate on her own again. We took her to the vet and because she became lethargic and wouldn’t drink or eat. He couldn’t find a reason and said take her home she be “ok.” She started to tremble, and her gait became ataxic. She walked the walls of the rooms and wouldn’t hold her head or tail up. She was holding herself in isolated places. We took her back to the vet. X-rays found what was a mass in her chest, but not enough to cause her to not eat. We’d look into this after she got better. “Take her home and make her a hamburger.”
    Well, I made her chicken and potatoes and vegies and mashed it up and fed it to her. She ate with gusto, she ate PeanutButter bread in bits and I gave her water with a bulb syringe. Our hopes were up, but I’m a nurse and I know the calm before the storm. Tomorrow was Friday and by noon, I knew she was dying. I called the clinic and told them she was failing. Her gait was worse. She couldn’t stand on her own to void. She was refusing food. She was taking water by bulb syringe, typical of Nexgard polydipsia. So very thirsty, but she doesn’t know how to lap up water anymore, she hasn’t been able to do this for days now. We would give her back to God at 4:30 Monday.
    Saturday morning, she had a seizure while in bed with me. She has slept with us since we got her. The seizures became worse and worse. She became weaker. I called my vet and told him she was suffering and on Monday 4:30 may be too long, we need to end her suffering. The next day she started to cry with pain, that high pitched painful bark. There is no emergency vet nearby and my vet is over an hour away. So, we comforted her with Benadryl. This went on for the last 6 hours before we were able to take her release her to God. Our vet was able to get her in earlier that morning and he was very kind to us and to Molly.

  19. This product killed my boy. Gave him a dose in August 2022 and he was throwing up. In September on walks he was drooling and by January 2023 he crossed the rainbow bridge just after his 8th birthday. So angry at his senseless death. I’m left with a broken heart.
    Big pharma is evil.

  20. My senior Maltese was always sry and jumping around…I never used any toxins for fleas..He never got any…Then visited my sister and her dogs had fleas and my dog caught them from her dog…My vet gave me Nexguard. Gave it to him for 2 months with no side effects…When I gave him the 3 rd dose he had a seizure that night…Talked to the vet for and was told to keep an eye on him and to stop giving him Nexgard..well, a few months later…he had 7 seizures within 24 hrs. They didn’t last long and he recovered from the first 2 seizures and fell asleep…2 hours later the seizures although not lasting long were more intense and his recovery after was not going well along with the seizure now 2-3 hours apart..He was now walking into walls and not responding to my calling him …and just incoherent and walking all around and not stopping for 2 hours , getting into places that he could not find a way out …Bottom line was I had to put him down was told he may have had a brain tumor…I believe .Nexguard played a roll in this…Even though he was a senior dog he was still playful and prancing around..and up to then could still jump on an off the couch….No tests were done as I felt he was 16 yrs. Old and had reach the end of his life span….However, I have my own opinion now on this…as my dog never showed any signs of a growing brain tumor at any time…The cluster seizures started out of the blue Three months after the first seizures and d the last dose of Nexgard

  21. I gave my baby a nexguard chewable and six days later he was gone. This is ridiculous and must stop. He did not deserve this, he was in great health and he had a lot of life yet to live. I am beyond heartbroken. How do we stop this nasty drug and get it off the market??

  22. The new feline Nexgard Combo will also cause carnage. I brought my 15-year-old cat to the vet to have some old age symptoms checked out. His bloodwork came back with an elevated liver enzyme and anemia. Stupidly, I allowed the vet to put this poison on my cat, in case the anemia was caused by parasites. On the fourth day after application, he slipped off a table he was trying to jump on. Then, his feet started slipping out from underneath him when he was trying to eat at his food bowl. A day or two later, he stopped eating, and two weeks to the day of application, he was dead. Yes, old cats and dogs die, but they should not die a suffering death from being poisoned.

  23. hi there. Im Alvin and I’m from Malaysia. It was scary and sad when I read the comments . Can please someone recommend something that will replace nexxgard spectra and will protect and prevent my 11 months puppy from heartworm disease. I have heard of proheart injection. Will it be ok or are there any other chewable alternatives? Thanks

    1. Hi Alvin,

      there is a free in-depth guide right at the end of this article where you’ll learn about many different kinds of effective and natural protection options! They are all based on science!

      There are NO safe chewables or injections!

  24. You don’t mention if it’s safer using it on the skin instead of swallowing a tablet, I’d imagine it would be a lot safer, I’d never let my cat EAT flea treatment in the first place

    1. Hi Jason,

      Topical solutions are just as problematic. Imagine using them on children or even grown adults – pouring some liquid into your skin and believing you are now safe & protected for three months. I don’t think anyone would do it! Also, topical products are made by the same companies that make the chewables.

      Here is an article about one of the topicals, Frontline: https://ultimatedog.com/frontline-for-dogs-is-it-really-safe-and-effective/

      Don’t forget to download the complete guide to safely & naturally protect your pets from ticks and fleas. You can find it right at the end of the article, above the Sources! It’s FREE! 🙂

  25. Thank you for this informative post about fleas and ticks. It’s essential for pet owners to be aware of the risks these pests pose. Your insights are greatly appreciated!

  26. Wow, thank you so much for sharing this information!! I had a long conversation with my new puppy’s vet at his first check-up on whether or not flea/tick prevention medication is necessary, because I don’t want to put harmful chemicals in my dog that could be worse than the condition itself. I did agree with preventative heartworm medication though because I do believe the incidence of serious disease/death from heartworms is worth the (smaller) risks.

    Well he apparently didn’t like me questioning his treatment recommendations because he put all kinds of condescending notes in my puppies medical records like “O refused recommended preventative disease treatment because she doesn’t want “chemicals” that prevent disease in her dog”…like I was some crazy anti-vaxer, which for the record I am not, but pet medications/vaccines aren’t subject to the same intense scrutiny human meds are. I also refused the Lyme vaccine he kept pushing because I read it causes more adverse side effects than all other vaccines together, most worse than the symptoms of Lyme disease itself. Side note. I even came across an article written by a vet titled something like “First do no harm” and it was about how veterinarians shouldn’t be pushing Lyme vaccines unless patients are outside dogs in high wooded areas.

    But the vet repeatedly assured me flea/tick medication is safe and he’s the vet & knows best, so I eventually caved and agreed to Simparico Trio, a heartworm, flea & tick combo prevention “medication he said is the “safest on the market”. I asked why then was he pushing the Lyme vaccine if this medication protected against ticks & he said it didn’t work on the kind of ticks that cause Lyme disease (umm WHAT?!). I gave my puppy two doses of the Simparico Trio. I didn’t realize it made him sick because he also had his distemper vaccine that I was told could make him not feel well. But I suspicious & waited a few days after his last distemper vaccine to give him the Simparico and sure enough, within hours he stopped eating, became lethargic, weak, seemed less alert and generally just not like himself (it seems like he’s just starting to get back to normal now, 6 days later).

    Somewhat unrelated but definitely worth mentioning, a vet I saw for the 1st time (my vet was off) berated & yelled at me for 5 mins straight (I’m not even exaggerating) for “underfeeding” my dog because I told the tech I give him around 4-5 cups of dry food a day (at 4.5 mos old & not including the fresh pet he also gets every meal). He raised his voice and yelled at me like I was a child, telling me to give him 8 cups a day… “listen to me! You’re under feeding your dog and he’s malnourished! You are to give him 8 cups of food a day, do you understand? DO YOU UNDERSTAND? 8 cups! Give him 4 cups 2x a day!” I briefly said well I feed him 3x a day so…and he interrupted “I don’t care how you break up the 8 cups, just give him a total of 8 cups every single day! 8 cups on Monday, 8 cups on Tuesday, every single day! Got it?!” And then he slammed a measuring feeding cup down in front of me & said “use this!”, because I told the tech earlier that 4-5 cups was an estimate cuz we use a scoop (I measured later, it was 5 cups of dry food day). I was in shock cuz I really didn’t understand the aggression, I mean I get really mad when people neglect their dogs too, but my 4.5 month old boxer weighed in at 43 lbs that day and doesn’t look malnourished at all! He looks like a normal, well defined muscular boxer puppy who’s barrel chest drops low and then slopes upwards towards his stomach. You can’t see his ribs, no bones jut out, and I knew I was feeding him OVER the recommended guidelines because I thought he was underweight & undernourished when I brought him home (which I told his primary vet I was concerned with at his 1st visit, and he agreed he was a bit under-muscular, but said he wasn’t unhealthy). I went out of my way to fatten him up, feed him the healthiest all natural food and had to find ever more creative ways to get him to eat cuz he’s a picky eater. I was actually proud of how much healthier I got him to look, only to bizarrely be screamed at and actually accused of neglect by a vet I had just met that day. I take very good care of my dogs, they’re part of my family! I pre-ordered genetic health screening for him on my own and sent the samples out the day I brought him home. When the first vet heard a murmur at his 1st visit but said he could grow out of it so we should wait, I insisted on getting a referral for an echocardiogram rather than waiting to see if it got worse (which btw, it unfortunately turned out to be Mild Tricuspid Valve Regurgitation, a really bad early genetic cardiac disease that has a 3 year life expectancy, or an individual malformation that can cause cardiac disease years later…neither is good). I immediately got him in for a consult with Cornell (hours away), and I had just found all this out when this a-hole Vet (pardon my language) decided to berate me for no possible reason other than to exert dominance and power over a female imo.

    Sorry, long story short, that was the final straw. I left that practice & am seeking a new vet I trust. In the meantime I joined Dutch for heartworm recommendations and the vet said Heartguard plus is safest & after reading numerous articles on it, I concurred. But he also recommended Nexguard for flea/tick and I was getting ready to buy it after doing my due diligence with research and every article saying it’s safe, when I came across this article, and it stopped me in my tracks! I removed it from the cart and only purchased the heart guard plus. I’ll look into natural sprays/methods, so thank you so so much!!! Sincerely, thank you.

  27. Katy’s SunFlowers

    I’ve been using this on my toy poodle since she was 2 months old cause the vet told me to. A week ago she had her first episode and yesterday her second one 🙁 the vet didn’t tell me anything about these pills, they actually have it behind the counter selling them to dog owners. I asked her if it was her food, or the medication she said “No”. She found nothing wrong with her. And today she will send me blood results which I’m sure will find nothing…. 400$ spent and she knows nothing. All vets are like this. Just there to fill their goddamn pockets!

  28. We lost our beloved 10 year old Red Heeler, Ginger, six weeks ago after 6 days of diarrhea that came out of no where, and on her last day she woke up paralyzed. We were so worried about her and got an emergency appointment with the vet who said the most humane thing to do was euthanize her as there was nothing that could really be done at her age to improve the situation and doing lots of tests and procedures would just cause her more discomfort. We were so shocked and taken back but decided to euthanize her. I had started looking up Nexgard Spectra a few days into her diarrhea as the day before it started she had her second dose of Nexgard. We had changed her meds from a topical med at the recommendation of the vet since topical flea meds aren’t advised if you have multiple dogs who play fight and we had recently adopted a second dog. We put both dogs on Nexgard Spectra… the new pup had no side effects but Ginger died. I am still gutted! I chose to trust the vet and my ignorance killed my dog. We loved her so much. My kids were heartbroken. We immediately took our new dog off all chemical flea meds and are pursing natural options now. I want others to know so they can make an informed decision when they choose meds for their pets. It’s so maddening to think it was one little pill and my beautiful dog was gone. Soooooo maddening and so heartbreaking. Thank you for your site. It was so informative… just too late. But I share it with my friends in hopes it can save another pet.

  29. Would you recommend Seresto instead?
    My dog has allergies and we are struggling a lot with them. i tried everything and last time the vet gave me NexGard Spectra. Only now that i’ve read the article I am terrified.
    I need to have somthing to protect him but i do not know what. Natural things might not work good for him and his allergies.
    I will also try quercetin ( thank you for the other article) . I was prepared to take apoquel but I will go with quercetin suplements.

    1. My pup has a skin allergy that just seems to be getting worse and not better. I noticed it early on so I think she is not nearly as bad as some get but her coat has thinned substantially and she’s just started with “hot spots”. We have tried all the things including diet changes and it doesn’t help. Finally I thought what about nexgard, maybe it’s the nexgard she is allergic too…only thing that hasn’t changed in the year we have had her, so I’m ruling out possibilities. I hopped on to the net to see if there were any results for “could my dog be allergic to nexgard” and low and behold there is a plethora of information citing potential skin allergies from the use of this product…never mind all the other very scary side effects. What really gets me, is that when I asked my vet if it could be chicken I was told vehemently “no” – yet a holistic vet and various internet resources have cited this very thing as a huge potential allergen trigger in dogs! Also, Not once has my traditional vet (3 different ones have seen her) even reported that nexgard could be a potential issue. I don’t expect a vet to say don’t use a product they think works, but I DO expect a vet who has a pets best interests at heart, to rule out the possibilities and assist in finding the cause and not just treating symptoms! No, they just want to have her on prednisone tablets for the rest of her life!!!!! I’ve lost all faith in the medical system for us and our pets – like everything in life – do your own research, and when there are too many coincidences or chatter around d things then chances are there is some legiticacy to what you are reading or learning.

  30. Thank you for your site. It was so informative and helpful.

    From Hong Kong, one of the victims that using Nexgard for the dogs, and one is suffering from seizures at this moment.

  31. Thank you for your site. It was so informative and helpful.

    From Hong Kong, one of the victims that using Nexgard for the dogs, and one is suffering from seizures at this moment.

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