The People's Perspective on Medicine

Be Careful with Flea and Tick Medicines

The FDA has issued a warning to pet owners that some flea and tick medicines could cause neurologic side effects such as trouble walking or muscle tremors.

Fall is here, or nearly so. That means the worst flea season is right around the corner. Fleas love the more moderate temperatures and humidity as we head out of summer and into fall. As pets start to grow thicker coats, fleas also find it easier to hide. There are new worries about popular flea and tick medicines.

What Flea and Tick Medicines Do You Use?

Many people prevent flea and tick infestations by dosing their pets with a chewable medicine such as Bravecto, Nexgard or Simparico. All these treatments contain compounds related to isoxazoline. This pesticide works by shutting down GABA-chloride channels in the nervous systems of the fleas or ticks.

A New Warning about Side Effects of Flea and Tick Medicines:

The FDA recently approved a new drug in this class, Credelio. At the same time, the agency issued a warning for pet owners. These chewable medications are considered safe for most animals, but they can cause neurologic side effects. Some animals experience muscle tremors, trouble walking or seizures as adverse reactions to these flea and tick medicines. If you notice any unusual neurological symptoms after dosing your dog or cat with oral flea and tick medicines, report the problem to your veterinarian and to the FDA promptly.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
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We just took our 2 yr old dog off Bravecto after reading your article here. There is a company here in Florida who makes a flea and tick natural medication which has garlic and vinegar in it. Haven’t tried it, but it looks good on paper. Has anyone tried this? I’ve also heard that plain garlic is effective also, if mixed in their foods. Any thoughts?

Garlic is considered toxic to dogs, so please don’t add it to their food. I’m not sure how safe a flea treatment would be that contains it.

My 6 year old toy poodle has been on Trifexis since she was a puppy. I am blessed that she has never had a problem with Trifexis, but I can truly understand how any pet owner might feel about giving their pets a poisonous type of chemical. With my former dog, I did apply some chemical to her neck monthly, can’t remember the name, but she hated it.

Any natural products to use for flea and ticks,how much to give have a 11 # chiluala where do you buy it.

I experienced this about 25 years ago. I used a single dose of flea treatment on my cat (applied to skin on the nape of her neck, as usual), and she was drooling and had bad tremors for days. These tremors reappeared regularly for months afterward and never really went away. It was very scary. I used only ONE dose on her! I wrote to Hartz Mountain about this, and they never replied to me. So I will never again buy any of their products. I only use Advantage now on our cats. No problems.

The numerous reports here certainly support the fear of destructive chemicals being used in and on our little buddies. I will not use another chemical on or in our aged dog. The owner who uses brewer’s yeast made sense. I have no idea how that would be a preventative, but I will certainly give it a try.

My cat showed signs of illness each year after the vet gave her a flea prevention shot. For the past few years I have fed her nutritional yeast mixed with her food. She eats dry organic food with sweet potato dry food and turkey and salmon canned. I give her roughly 1/2 of 1/8 tsp.of yeast per day total. She loves the taste, and she has had zero fleas .

I have read that nutritional yeast may have too much B6 for cats. I am wondering if this is true.

We live in Missouri and have 4 dogs & 5 cats-all are indoor/outdoor pets. We haven’t had any flea problems in the 10 yrs. we’ve been here! Last summer we tried a topical for tick prevention (which we do have lots of). The cats all freaked out very shortly after application. Running like mad thru the house, got outside, rolling in the dirt to get it off. One came back in, screaming & running thru the house, frothing at the mouth. We managed to catch her, sprayed her off in the bathtub & managed to get the “med” washed off. She calmed down quickly and was fine very quickly. We cleaned the other cats & they were fine. The next day we noticed that one cat had a bald spot between her shoulders where the liquid had been placed! We got rid of the med & decided never to use a topical on them again! That was the first time that we had tried a topical- our cats range in age from 16 to 8, and, luckily, there were no lasting complications.

We don’t like to use chemically treated collars on any of our pets as we hold, pet & sleep with them, plus there’s the possibility of a cat getting stuck on a fence or in brush as they explore our country property. It happened to one of our twin males who we collared so we could tell him from his brother. He came back one day collarless &a little bedraggled. The collar was found in some vines a few days later. It was a break away that worked but he sure looked like he had struggled to get free. This was the first time any had been collared. No more collars for the cats. Our dogs have been getting chewable flea & tick meds, but we are going to change that. Any suggestions? Thanks for this article!

I agree with one commenter: why on earth would you allow your darling pet to EAT POISON?! I do use one brand, however, on my 4 fur-babies (cats) and they have never had any problem! It’s a bit pricey but well worth it. IMHO.

I read an article saying that vinegar added to the pet’s water each day would repel the fleas. I tried it but my dogs did not want to drink the water. You know the old saying ‘you can lead a ‘horse’ to water but you can’t make him drink. How can you get the dog to start drinking it? That is a natural way of not having to deal with fleas.

I am using Trifexis for my 16 yr-old toy poodle. She has gastrointestinal & gall bladder issues, and my vets are adamant that not being treated is dangerous here in Houston, a hostile environment for evil critters. Plus, she’s out on occasion with other dogs. I stopped for awhile when she was quite ill last spring but they convinced me to restart. SO confusing. Damned if you do or don’t. :(

Thank you very much for this warning. However, given that fleas and ticks are a big problem, it would be very helpful if you could make some suggestions for a safe product to use instead. I have tried brewer’s yeast, but that did not work. Any ideas?

I gave my Yorker Simparica and he began shaking several days later. He had never done this before. I called the vet and was told the shaking was unrelated to the medicine. MY baby became progressively more involved neurologically over the next year with decreased vision and hearing. I was told he had doggie dementia and would not improve. I do believe the flea meds were toxic for him.

Why on earth would you FEED your animal an insecticide? Would you eat one? This is nuts – use an herbal flea collar!

Herbal does not necessarily mean safe. I used an herbal flea med on my cat, applied as directed. Within half an hour he was drooling and shaking all over. When I googled the med and symptoms, I founds dozens of the same problem after using the med on cats.

Don’t administer on the same day as heartworm prevention

I’ve always fed my cats and dogs Brewer’s yeast (nutritional yeast) which I buy in bulk at my Food Co-op. Supposedly the yeast helps repel fleas…all I know is, I’ve used this natural repellent for many years for my pets. They love it and, since they’re flealess, I do too!

How much do you give your dogs? Do you sprinkle it over the dog food? After reading your comment, I have a Yorkie that I want to convert to Brewers Yeast.

I never use this stuff; if you research them, you will find nothing new here. There are many alternatives on the market if one takes time to look. Some do not work…many do. Garlic pills from SPRINGTIME work; spraying yards with non-toxics work, cedar oils, others available at Lowes, Tick tubes on line, etc., many others. I have 3 dogs…not a flea in 20 years, & I did get one tick this year.

How do you give your pets Brewers Yeast to treat them for fleas and ticks?

In my opinion, one of the best flea medicines for dogs and cats is Advantage. The concept behind it is ingenious. It is not taken internally, so it can’t harm the animal. It is a very mild poison, deadly to the fleas, but harmless to the dog or cat if they accidentally ingest it. You squirt it on the nape of the animal’s neck. The medicine works it’s way around the animal’s body as they move. The fleas fall off him. You don’t need a prescription to buy it. It is available OTC at places like Walmart.

It was the Sargeant’s Flea & Tick medicine that almost killed my two Pugs several years ago. And it DID kill many dogs, cats, etc…. and of course nothing was done about it. There was an internet site where pet owners could write about what Sargeant’s medicine did to their pets, and the ones that died were/are heartbreaking. I will personally never use another ‘flea & tick’ medicine. Because there is NO oversight to protect our beloved pets from these very cruel and greedy pet medicine ‘providers.’

I have two cats that spend a small part of their day outside. Managing the ticks and fleas they sometimes collect in their fur is certainly a challenge. A few years ago, I used the well known, veterinarian recommended “FL” between their shoulder blades, as directed on the label.

Within a week or so, one cat developed a twitch that never went away, and the other cat developed skin issues. I quit using the product and will never use it again. I consider the use of these products cruel, as it is little more than the slow poisoning of a defenseless animal.

“Some animals experience muscle tremors, trouble walking or seizures as adverse reactions to these flea and tick medicines.” <– That's not surprising to me since you're feeding your animal a toxin. We simply won't use these types of treatments.
I also hate to use heartworm medicines but I do simply because the threat in this area is too great not to treat. I do give as little heartworm medicine as possible and do not use it year round. Getting slightly off topic but heartworm medicines should not be called preventatives – they do not prevent heartworms they kill off existing heartworms in varying stages by giving the pet a toxin.
There are effective alternatives to toxic, synthetic chemical flea and tick medicines.

What about Revolution? I know it is neither oral nor chewable, but is applied topically and also kills heart worm. But how safe is it?

What is safe to use on our pets instead?

There must be a better way to keep fleas and ticks off cats and dogs than putting poison into the animals. I expect that flea powders and collars also introduce toxins into our pets, There is money to be made if someone can find something better.

Just curious, are these sorts of pesticides used to treat farm animals to kill fleas and ticks on them? Are we consuming residues of these chemicals in meat and milk?

Our dog has been on Nexgard for 5 years and never experienced the symptons mentioned. He is now around 10 years old. Do you recommend staying on it? “If it ain’t broke, don’t fix it” sort of thing. He is on meds for congestive heart failure as well as heartgard.
Please advise.

I can tell you that I’m unalterably convinced that Nexgard killed my beloved Boston terrier. His health and condition were impeccable–the best 10-year-old dog you’ve ever seen, able to hike 7 miles at my side, until he’d been on Nexgard for about three months. I started finding the newly arrived black-legged (Ixodes) ticks on him in mid-winter and panicked. I didn’t want him to get Lyme disease.

So, on the advice of his veterinarian I started giving him Nexgard. Within three months, he went deaf; his thyroid shut down; he developed a weeping and unresolvable skin infection; his heart displayed a murmur, and he was dead at 12. His decline was absolutely horrible; he was on 7 medications when he died. I stopped the Nexgard, of course, but it was too late–the damage had been done.

I was told that Nexgard “has no side effects.” We give it to our dogs in good faith, sold on the claims of the manufacturers, reassured by veterinarians who trust the manufacturers. It’s a systemic poison, and we must never forget that. If you wouldn’t take a systemic poison, why would you give it to your beloved dog?

I’m so sorry for your loss of your beloved companion. As a veterinarian for 25 yrs, long before Nexgard and other similar flea/tick products were available, I learned and have observed that as a breed Boston Terriers often develop heart disease &/or cancer around 10-12 years of age, and hearing loss is common around this age as well, though generally progresses slowly over time. Hypothyroidism is also not uncommon in older dogs. The Nexgard may have been an unfortunate coincidence with his aging process.

Since these products have been introduced, we have had some patients that are prone to seizures have an increase in their seizure activity. Once the product is stopped, they go back to their typical level. We do have some patients that are prone to seizures that have not had any increase in seizures when their people, understanding the possible risk, elected to try one of these products due to significant flea and tick issues that were not controlled by other products. I have seen no deaths or irreversible side effects so far with these products. We do see significant disease caused and spread by fleas and ticks, and some areas of the US see far worse diseases that we do here. I would prefer to use no insecticides on my furry kids, but considering the alternative and potential to bring these pests and their diseases inside to the rest of our family, I strive to keep current on the most effective fleas products with a good safety profile and use those with my critters. I do currently use Nexgard with my dogs, one of whom is 13 years old and has been on it for 5 yrs during fleas and tick season, and is doing well for his size (70lbs) and age, still enjoying hikes in the woods.

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