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Flea Control Product Poisoning

Pyrethrin Toxicity


Flea and tick control products for cats come in a variety of forms: collars, powders, dips, sprays, and spot-on products, to name a few. Although there are several different types of active ingredients used for flea and tick control, the most common ingredient is pyrethrin, an insecticide that is used in pet products to repel fleas and other insects as well as to repel insects from food plants. A natural organic compound derived from the seed casings of the chrysanthemum flower, this highly effective insecticide attacks the nervous system of insects while remaining harmless to mammals, as long as the levels are very low.


Toxicity most commonly occurs as a result of improper use of flea and tick control products, particularly over-application or use of a product that was formulated for a different species. Cats are much more sensitive than dogs are to pyrethrins, and because the level of pyrethrins will be higher in a flea repellent that has been formulated for dogs, cats will commonly fall ill after being treated with a flea or tick product made for dogs.


The synthetic versions of pyrethrin, permethrin and other pyrethroids, have an even higher incidence of toxicity for cats when used improperly (the toxicity risks also increase for humans).  Users can distinguish other synthetic pyrethroids in insecticide products by looking for ingredients that end in "thrin" in the ingredient list.


What to Watch For


  • Excessive drooling
  • Muscle tremors, staggering (ataxia)
  • Possibly seizures
  • An agitated or over excited state
  • Vomiting, diarrhea, difficulty breathing or hyperthermia (less common)
  • Evidence that a pyrethrin or permethrin containing product was applied recently


Primary Cause


Toxicity is caused by an overdose of topical (external) flea and tick control products containing pyrethrin, permethrin or other pyrethroids. It can also result from using pyrethrin containing flea products made for dogs, which are made with higher levels of pyrethrin — levels that are unsafe for cats. Toxicity can also occur as a result of ingestion, such as when a cat grooms itself or licks another animals (including dogs) that have been treated with a pyrethrin product.


Immediate Care


If your cat is wearing a flea collar or other insect repelling device, remove it.

Call your veterinarian or the Pet Poison Helpline at 1-855-213-6680 immediately to determine if your cat has been poisoned.


Veterinary Care




Diagnosis is based on symptoms and history of recent exposure to pyrethrin-containing products.




Treatment will be given to control symptoms as needed. Most commonly, medications to control tremors and seizures, along with intravenous fluids to maintain hydration.  If symptoms are severe enough, your cat may need to remain hospitalized for a few days until symptoms subside.


Other Causes


Because pyrethrins are so effective at insect control, products that are formulated for insect control in and around the home, including gardens, can also be found in the cat’s environment.


Living and Management


There are usually no long-term effects from overdosing if the cat receives immediate treatment. If you used a pyrethrin containing flea and tick product that was formulated for cats and you are sure that it was applied properly, and your cat still showed signs of toxicity, do not use a product that uses pyrethrins. Talk to your veterinarian about a good alternative for your cat.




The most important way to prevent overdose is to read labels and follow the directions: how much, how often, and how to apply the product on the cat. If you cannot find this information on the label, do not use the product. Make sure the product is labeled for cats; you cannot substitute with flea and tick products made for dogs.


In addition, all flea products have a minimum age for use, kittens must reach a certain age before they can be treated with any kind of flea or tick product. Most products also have a minimum weight. The amount (or dose) of pyrethrin used in a formula often will vary according to a cat’s weight. Make sure that you are choosing the formula that best matches your cat’s age and weight. Also keep in mind that because cats groom each other, you will need to keep them separated after applying a flea or tick product until the product has dried.


Common synthetic pyrethroids: bifenthrin, permethrin, allethrin, tetramethrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin

Comments  5

Leave Comment
  • Natural flea control
    08/27/2014 05:54pm

    Several years ago, I had a part time job as a pet groomer in an animal hospital. While there, I saw several cases of pets that had had terrible reactions to the toxins in most flea control products. These were not cases of misuse of the products, it was because of the product itself. I then decided that I would never put poison on any of my own pets again. There are many natural ways to control fleas and ticks without poisons. The use of poison anywhere of any reason is never a good idea for anyone. I use a couple of products from Only Natural Pet. I use their squeeze on product and a daily dose of their brewer's yeast tablet. I have done this for a couple of years now and have had no fleas or ticks. I do use their spray as well when the dog is going to be walking through wooded areas of fields. Works like a charm for my gang!

  • 08/08/2016 04:44am

    where do you buy the Only Natural Pet and how do you give the brewers yeast tablets for a cat 9 months old? thank you

  • 08/08/2016 01:08pm

    Only Natural Pet has a website by the same name. That 's where I buy it, but you might be able to buy it from Amazon. Not sure. I only give the brewer's yeast tabs to my dog. He spends more time outside than the cats. My cats go out, but they are in an enclosed area so they can't get away and nothing can get at them. I guess if I were to give it to them, I would first ask my vet about dosage and the easiest way would be to crush it into their food. I've found that that's the easiest way to give any kind of medication or supplement to cats. I hope this will work for you. I have used it for a few years now, and so far, no fleas! Just be sure your pet is flea free to begin with because this stuff only repels, it does not kill--because there is no poison.

  • Frontline causes seizures
    03/27/2015 05:28am

    My dog started having severe seizures because I had used Frontline on her. It was so bad that she had 3 seizure in one night when they first started occurring. At the time, I had no idea that this was what had caused it. it was only after I had heard of the same thing happening to other people's dog after using Frontline that I made the connect between the product and her seizures.

  • My cat has died!
    08/06/2016 05:26am

    MY cat died in June 2016 and had been prescribed Comfotis and Cheristin for Cats.

    She had been on these two products made by Elanco and they contain Spinosad and Spineforum respectively.

    These poisons killed by dear cat and Elanco won't admit it. Shame on this evil pharmacy and shame on veterinarians that are selling these products contained this pescide, including Trifexis for dogs.

    This is a very sad situation at best. When I think of how my dear cat died, it sickens me to the point of tears.


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