Is Cypermethrin toxic to cats?
No. Cypermethrin is another pyrethroid insecticide, closely related to permethrin, and cats cannot safely metabolise it either. It's found in some dog flea products, household insect sprays, and garden/outdoor insecticides — all are dangerous to cats.
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Content compiled with reference to guidance from the Blue Cross, PDSA, Royal Veterinary College (RVC), Battersea, and Animal PoisonLine. This site does not provide veterinary advice — always consult a vet. Last reviewed: 27 September 2026.
Key facts
- Verdict: No — dangerous to cats. Cypermethrin should never be given deliberately.
- Category: Flea/parasite treatment
- Onset: Signs can start 0–3 hours — see the full timeline below.
- If it's already happened: Call your vet now, or the Animal PoisonLine on 01202 509000 (24/7, charges apply) — see the emergency steps below.
If your cat has just eaten cypermethrin
- If cypermethrin is still on your cat's fur or skin, wash it off with warm water and a mild dish soap (e.g. Fairy Liquid) — but only if your cat is alert and not seizuring.
- If your cat is tremoring, twitching, or seizuring, go straight to the vet — do not delay for bathing.
- Call your vet immediately and tell them it's a pyrethroid/cypermethrin exposure — they will recognise this as a time-critical emergency.
- If you can't reach your vet, call Animal PoisonLine (01202 509000) — paid triage, 24/7.
What's the full picture?
Cypermethrin belongs to the same chemical family as permethrin (both are synthetic pyrethroids) and works on the nervous system the same way. Cats lack sufficient activity of the liver enzyme (glucuronyl transferase) that dogs and humans use to break pyrethroids down quickly, so cypermethrin builds up to toxic levels far more easily in a cat than in a dog exposed to the same product.
Unlike permethrin, which is mostly known via dog spot-on flea treatments, cypermethrin turns up more often in general household and garden insecticide sprays, ant and crawling-insect killers, moth-proofing treatments, and some outdoor wood treatments — as well as in a smaller number of dog-only flea and tick products. Read the active ingredient on any spray or treatment before using it near a cat, or letting a treated area dry before your cat has access.
Signs of pyrethroid poisoning in cats are the same regardless of which specific pyrethroid is involved — cypermethrin, permethrin, and similar compounds (deltamethrin, bifenthrin) all produce the same tremor-and-seizure picture and are all treated the same way by a vet.
As with permethrin, exposure doesn't require the cat to be the direct target — grooming a treated dog, walking across a recently sprayed skirting board or garden path, or sleeping on treated bedding are all recognised routes.
Symptoms to watch for
Hidden sources you might not think of
- Household insect sprays (ants, flies, crawling insects)
- Garden and outdoor insecticides
- Moth-proofing treatments for carpets and fabric
- Some dog flea and tick spot-on products
- Wood and timber treatments
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Questions owners ask
Is cypermethrin the same as permethrin?
They're different chemicals but both are synthetic pyrethroids that work the same way and are both highly toxic to cats. If a product label lists either as the active ingredient, treat it as dangerous around cats.
My cat walked across a floor I'd just sprayed with an insecticide — is that a problem?
Check the label for cypermethrin, permethrin, or other pyrethroids. If present, keep your cat off the treated area until it's completely dry (follow the product's stated drying/re-entry time), and watch for drooling, twitching, or tremors.
How much cypermethrin exposure is dangerous?
As with permethrin, there's no safe dose for a cat — cats can't break down pyrethroids the way dogs and humans can, so even indirect exposure (walking across a treated surface, grooming a treated dog, contact with treated bedding) can trigger serious poisoning. Any suspected exposure to a cypermethrin-containing product needs immediate veterinary attention.
When should I go to the vet vs monitor a suspected cypermethrin exposure at home?
Always go to the vet rather than monitor at home. Early signs — drooling, twitching, ear flicking, restlessness — can progress within hours to severe tremors and seizures, and the window for effective treatment narrows the longer you wait. This applies whether the exposure was direct contact with a spray, a treated dog, or a recently sprayed surface.
A lockable medicine box is the simplest way to keep human tablets out of reach of a curious cat.
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Related
Sources referenced for this guidance
- Veterinary Poisons Information Service (VPIS) — UK clinical toxicology reference used by vets
- International Cat Care — feline-specific clinical guidance
- BSAVA — British Small Animal Veterinary Association reference materials
- Merck Veterinary Manual — professional veterinary reference
About this guidance
Every entry on this site is compiled from published UK veterinary toxicology sources — International Cat Care, Veterinary Poisons Information Service (VPIS) references, RCVS-registered practice materials, and peer-reviewed feline medicine literature. Where the evidence is mixed, we err on the cautious side because cats are unusually sensitive to many common substances that are harmless to humans and even to dogs.
This is general information written for UK cat owners. It is not personalised veterinary advice for your specific cat, their age, weight, medical history, or the exact exposure you're dealing with. If your cat has eaten something or is unwell, call your vet first. The Animal PoisonLine on 01202 509000 is available 24/7 for a small fee and can tell you whether an emergency visit is needed.
Entries are reviewed and updated as new research emerges. Spotted an error? Let us know — corrections are investigated and applied within 24 hours. For more context on how we work, see about and our full disclaimer.
Last reviewed: · By the What Can My Cat Eat? editorial team