Fleas are a common pest for both cats and dogs. Fortunately, there are a variety of products available to help prevent infestation. When used as directed, such products are safe and effective. However, dogs and cats can easily become sick if too much or the wrong flea product is applied, or the product is ingested post-application. Ingestion occurs if the dog or cat licks the treated area. Below is more information about potential reactions and flea control product toxicity in pets.

The most common type of flea control product is pyrethrum-based. As you look at the product label, you will see the main ingredient listed as a pyrethrum, pyrethroid, or permethrin. The active ingredients in pyrethrum-based flea products include allethrin, bifenthrin, cyfluthrin, cypermethrin, cyphenothrin, deltamethrin, esfenvalerate, etofenprox, fenpropathrin, fenvalerate, flumethrin, imiprothrin, metofluthrin, permethrin, prallethrin, resmethrin, silafluofen, sumithrin, tefluthrin, tetramethrin, tralomethrin, transfluthrin as well as others. Some brand names may include Talstar, Capture, Ortho Home Defense Max, Bifenthrine, Baygon, Scourge, and Anvil.

The other type of flea product that can cause toxicity contains organophosphates. Active ingredients in organophosphate products include chlorpyrifos, crufomate, dichlorvos, diazinon, haloxon, naphthalophos, phosmet, naled, tetrachlorvinphos, and malathion. Brand names may include Alco, Americare, Beaphar, Ford’s Freedom Five, Happy Jack, Hartz, Hopkins, Kill-Ko, Protection, Rabon, Sergeant’s, Unicorn, Vet-Kem, Victory, and Zema.
Many of these products are safe and effective when properly used. However, these products also carry risk of toxicity and other adverse health consequences if used incorrectly. As such, it is important to confirm the flea control product is appropriate for the species, weight, and age of your pet.

Signs of Flea Control Product Toxicity in Cats and Dogs

Signs of flea control product toxicity can occur from one to 12 hours after application and may vary depending on the type of flea control product poisoning.

The most common signs of toxicity from pyrethrum-based flea products are muscle tremors and excessive salivation.
Common signs of toxicity from flea products containing organophosphates are diarrhea, vomiting, difficulty breathing, small pupils, muscle tremor, weakness or falling over, and drooling. Organophosphate toxicity can be rapidly fatal, depending on the ingredients and dose the pet is exposed to.

What to Do if Your Dog or Cat has Flea Control Product Toxicity

If you notice any signs of toxicity, contact your veterinarian. It is generally recommended that you immediately wash your pet with warm water and a mild detergent, such as Dawn® dishwashing liquid. Pets can chill easily so dry thoroughly after bathing and keep your pet warm. After bathing your pet, proceed to your family veterinarian. If unavailable, find your closest veterinary emergency clinic.

Will My Pet Recover from Flea Control Product Toxicity?

Pets becoming ill from exposure to a pyrethrum-based flea control product can make a full recovery with prompt treatment including intravenous (IV) fluids, muscle relaxants, and symptomatic care.

Pets poisoned by organophosphate flea products require early intervention, which almost always requires IV fluids, supportive care, and hospitalization. With prompt treatment, a full recovery can be expected in most pets.

Prevention of Flea Control Product Toxicity in Dogs and Cats

Most flea control product toxicities are a result of not following label directions. Prior to using a flea control product, always consult with your family veterinarian as well as confirm the product is appropriate for the species, weight, and age of your pet. Cats are more sensitive to the toxic effects of pyrethrums and organophosphates than dogs, so take care when using flea control products of any type on a cat, and never use a product intended for a dog on a cat.

Additionally, since kittens and puppies are more sensitive than adult cats and dogs, be sure to use flea control products approved for kittens and puppies, as many have age restrictions and are not approved for use at young ages.

Do’s & Don’ts to Using Flea Control Products in Cats and Dogs


  • Consider using a veterinarian-prescribed flea control product for safer, more effective treatment.
  • Read label directions carefully to ensure the flea control product is appropriate for your pet’s species, age, and weight.
  • Separate pets in a multi-pet household until the flea control product is dry so pets cannot lick topical products off each other.


  • DO NOT apply a topical flea control product to skin that is red, irritated, scratched, or broken.
  • DO NOT use more than one flea control product on your pet at a time, unless directed by your veterinarian. Even two safe flea control products can be dangerous when used together.
  • DO NOT EVER apply a flea control product for a dog to a cat without the approval of your family veterinarian.

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