Can Flea Collars Cause Seizures in Dogs?


Q:I have an older dog — a 10-year-old golden retriever — that I just adopted from a rescue. When I put a Seresto flea and tick collar on her, she started having seizures. She no longer has the collar but is now on phenobarbital to control the seizures. What do you advise using for flea and tick control on a dog that has a history of seizures? I know that the new pill is not advised for these dogs.

Kathy Waterhouse
Barrington, NH

A:You are not alone in your concern. There are a number of anecdotal reports online of flea collars causing seizures in dogs. But none of them is even remotely substantiated. The chances that a Seresto collar was the cause of the seizures in your pet are remote to nil.

Seresto contains two active ingredients: imidacloprid (an insecticide to kill fleas) and flumethrin (an insecticide/acaricide combination that kills fleas and also ticks). Both are very safe for dogs at the doses present in the collar and only very rarely cause adverse reactions — and not seizures. The most common reaction is dermatitis (inflammation of the skin) at the contact area. There have also been occasional cases reported of intoxication as a result of dogs ingesting the collar, dogs overdosed because the wrong-size collar was used, or dogs being unusually sensitive. Signs have included tremors and lethargy. The collar has never been documented as a cause of seizures, and certainly not ongoing seizures requiring routine phenobarbital treatment once the collar has been removed.

As far as the “new pill” you say is “not advised for dogs,” we assume you mean Bravecto, Nexgard, or Simparica, all of which protect against fleas and ticks. But according to data amassed by the U.S. Food and Drug Administration and the European Medicines Agency, none of these drugs has any contraindications. They do talk about possible allergies to ingredients, but that’s true for any drug. There’s no reason not to use these medicines in dogs who have seizures. That said, topicals such as Advantix, Effitix, and Vectra 3D are usually preferred by owners, who find it easier than giving drugs by mouth. Any one of these spot-ons will do the trick.

Lluis Ferrer, DVM, PhD, DECVD


  1. I have a 16 year old golden. Two days ago we introduced the Seresto Flea and Tick collar. Last night and now today, we are experiencing seizures???? This has never happened before. Granted, she is 16 in a few weeks but everyone who looks at her doesn’t have any idea just how old she is because she is pretty spry for her age. Coincidence??? Hmmmm

  2. We have a 2/12 year old Cavapoo and a one year old Cavachon. We used the Seresto collar with the Cavapoo with no problem. We also use the collar on the Cavachon and she started have seizures (head cocked sideways and shivering, walking somewhat sideways). We didn’t connect the collar to the condition. One vet suggested starting her on anti-seizure medication, a series of expensive tests, etc. We went for a second opinion and he suggested removing the collar for a period of time to see if anything changes. We removed the collar and within a week the seizures stopped and she hasn’t had any since. We’ve switched to an oral flea/tick medication and all has been fine…..

  3. I have a year and a half year old Lab, Great Pyrenees mix that started having seizures after I put the collar on him. I asked the Vet if they could cause seizures and they didn’t think so and put him on meds. He was fine for a week or two and then I put the collar on him and he had another seizure on the second day of wearing the collar again.

  4. I disagree with this vet and this article. I have multiple epileptic dogs and the “new pills” most definitely cause them to have seizures (bravecto for sure). We have Had to try various medications to see what works best for each of mine which is no easy task. Same with heartworm medications. I do have good luck with Advantix 2 and revolution on one but every dog is different and you have to be careful and find what works for you! My vet gives Valium the day before, day of and day after any of these meds to prevent the seizures. It works MOST of the time! I will be trying the seresto collars this year to see if they can tolerate them- here’s hoping! If not back to the monthly drops. Good luck everyone!

    • Hi! Thank you for your post. I, too, have an epileptic dog (Husky) who has picked up fleas this season. The neuro vet tech recently suggested Seresto as the safest over-the-counter flea treatment, but I am hesitant to introduce any chemicals. I have gone to great efforts to protect this dog from chemicals, but the DIY treatments do nothing! (have you ever tried to get anything to penetrate through a Husky’s thick coat?) SO, I’m wondering how your dog tolerated the Soresto collar.
      Any feedback would be greatly appreciated!

      • Hi Maureen! Although I don’t have an epileptic dog I have noticed that a few months after introducing Cody, my havanese to the Seresto collar he has begun having seizures which started in April of this year. He was wearing the collar for six months prior to him having seizures and throws up quite often. The vet stated it was from having an empty stomach which was bizarre to me because he is a little chubber for a small breed. Anyway I racked my brain thinking what can I be giving him to cause sudden seizures, blood work came back perfect so nothing was wrong on that end. I changed his diet and only give him poland spring water so I decided to look up side effects from the collar and low and behold there are quite a few. It’s safe to say, Cody will no longer be wearing any collar that has these chemicals although it definitely does the job as they claim. So if anyone has suggestions on any other type of medication that helps with ticks it would be greatly appreciated. Thank you


      • My dog Benji who has just turned 4 was fine with the drops such as Advantix and Frontline but it didnt get rid of the fleas so i put on the Seresto collar and in a couple of weeks he started having seizures…At first i didnt make the connection then i took the collar off and he was fine, I put the collar back on and 2 days later he had another seizure..I threw the collar out. I then gave him a bath with FLEA Shampoo and 6 hours later he had a seizure. Now he has no flea collar, i use Dawn dish soap for fleas and he hasnt had a seizure in 2 months. His liver enzymes were raised and through a lot of research i found out that the liver cleans the toxins out of the blood so I believe the collar kept pumping the toxins in until his liver couldnt handle anymore, Weve got him on a low protien(no red meat) diet to help keep his enzymes lower and we are hoping the his lack of exposure to chemicals will eventually allow his liver to get back to normal. Of course its a daily chore to literally search his body for fleas ..We had the house professionally fumigated, we stayed in a hotel that night so Benj wouldnt come in contact with the poisons they used. The fleas are STILL here. I have a cat as well but Im able to use Advantage drops on him but he still has fleas too. I vacuum and do a ton of laundry trying to keep ahead of the fleas birth circles but Im ready to pull my hair out! I have woodflooring in the entire house except the bedroom. Ive used clove oil,cedar oil, tea tree oil..all natural flea repellars but still found 5 fleas yesturday…Im too afraid to use the drops on Benji now because i want his liver cleaned and now he may be sensitive to any flea meds. The petsmart by me told me that 6 other people came in complaining that Seresto gave their dogs seizures..I wouldnt use it.

  5. I have a Lab/Pit mix and when we started using Seresto Flea collars about 2 yrs ago he started having seizures and we never connected the collar to his seizures our other 2 had no issues at all for the 2 years of wearing the Seresto during the spring/summer months. Now our boy is on all 3 seizure meds possible..phenobarbital, Keppra, and potassium bromide. Maybe I should bill Seresto for the cost of Aniaml Hospital at $1400. X3 a pop each time and all his meds he is on!!!!! 😔🐾🐾

    • Have you tried Zonisamide for his seizures? Our husky has seizures and he is only on it so far and so far it has worked wonders. We have to give it to him every 7 hours which is a pain I’ll admit but well worth it since he hasn’t had any seizures as long as he gets his med…

  6. I also disagree with this vet and article. My friend’s dog had seizures as well as soon as he started wearing the Seresto collar. The vet of course said the same thing that it was just a coincidence. They took the collar off and he has been fine since. We try to treat our dogs holistically and use Wondercide as well as a good old fashioned flea comb. I have had good luck with Wondercide up until this month. I think I wasn’t diligent enough in applying it so I used Frontline on both my dogs and one dog had a reaction. By the next morning our dog had bloody diarrhea and vomiting so I gave her a bath and will have to be more diligent with the Wondercide as well as vacuuming.
    Good luck everyone.

  7. Our dog who was just given a new Senestro flea collar had a seizure tonight. It was horrible. If this product is causing dogs to have seizures it should be removed from the market. We need to start a class action suit to get this company to stop selling this product. It is harmful to pets and should be banned.


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