Is Permethrin Toxic to Cats and Dogs?
Permethrin is severely toxic to cats and only mildly toxic to dogs. Using a DOG flea product on a cat is a life-threatening emergency. Call a vet at once.
Potentially life-threatening — treat any exposure as an emergency.
Usually minor, but watch for symptoms.
In an emergency, do not wait.
Medical disclaimer: This tool is for general information only and isnot a substitute for veterinary diagnosis or treatment. Toxicity depends on the amount, your pet’s size, and health history. If your pet may have ingested something harmful, contact your veterinarian or a poison control hotline ((888) 426-4435 / (855) 764-7661) immediately — do not wait for symptoms to appear.
What is Permethrin?
Permethrin is severely toxic to cats and only mildly toxic to dogs. Using a DOG flea product on a cat is a life-threatening emergency. Call a vet at once.
Also known as: pyrethrin, pyrethroid, flea spray, dog flea treatment, permethrin flea drop, advantix.
Symptoms to Watch For
🐈 In Cats
- Muscle tremors and twitching, often within hours of application
- Seizures that can become continuous
- Excessive drooling and depression
- Hypersalivation and loss of coordination
🐕 In Dogs
- Mild skin irritation or itchiness at the application site
- Drooling if the product is licked from the fur
- Vomiting or mild stomach upset with ingestion
What to Do If Ingested
- Note the exact product name and active ingredient from the label.
- Wipe any excess from the fur and prevent licking.
- Call a veterinarian if drooling or vomiting appears.
Steps apply to both cats and dogs. When in doubt, call a vet or poison hotline before acting.
When to Call the Vet Immediately
Call your veterinarian or a poison control hotline right away if you notice any of these:
- Tremors, twitching, or seizures (rare in dogs at label doses)
- Persistent drooling or vomiting
- A concentrated product was ingested
Frequently Asked Questions
Frequently Asked Questions
Why is permethrin so dangerous to cats?
Cats lack the liver enzyme (glucuronosyltransferase) needed to break down permethrin and other pyrethroids, so the chemical accumulates and attacks the nervous system. Dogs metabolize it efficiently, which is why it is safe for dogs at label doses but can kill a cat. NEVER apply a dog flea or tick product to a cat.
What should I do if I accidentally put a dog flea product on my cat?
This is a life-threatening emergency. Call a veterinarian or poison hotline immediately, note the product name and active ingredient from the label, and bathe the cat with mild dish soap to remove the product if advised. Do not wait for symptoms — tremors and seizures can develop within hours.
Can a cat be poisoned by sleeping near a dog treated with permethrin?
Yes, although the risk is lower than direct application. Transfer can occur if a cat grooms a treated dog or rubs against wet application sites. Keep cats away from dogs for 24 hours after a permethrin product is applied until it is fully dry, and call a vet if the cat drools or trembles.
Sources
This entry is reviewed against the following authoritative veterinary sources.
Last reviewed: 2026-07-11