FrançaisIs permethrin toxic to cats? What to do now
Yes. Permethrin is highly toxic to cats, and it remains one of the most common causes of poisoning in cats worldwide [10]. If a dog flea or tick product was put on your cat, or your cat was in contact with a dog just treated with one, call your vet or a pet poison line now, even if your cat seems fine [10, 11]. Keep the box or pipette so the vet can see the product and its strength.
Do not wait for signs. Washing the product off the coat is part of the treatment [9]; the vet will tell you whether to do it at home on the way, or will do it at the clinic. French authorities advise washing an exposed cat with lukewarm water and soap or dish liquid and seeking veterinary advice quickly, even before any sign appears [11]. Permethrin is one of several household products that are dangerous for cats; see also essential oils and cats and the toxic foods guide.
How cats are exposed, and why they are so sensitive
Permethrin is a synthetic pyrethroid, a man-made relative of the pyrethrins found in chrysanthemum flowers [9]. It is used in spot-on flea treatments for dogs, and permethrin spot-ons are contraindicated in cats [1]. Dog spot-ons can contain 45 to 65% permethrin, while the few low-strength products approved for cats contain 0.05 to 0.1% [6].
In most cases, the owner puts a dog product on the cat, by mistake or thinking a smaller amount will be safe [3, 5, 10]. Cats can also be poisoned by grooming or close contact with a recently treated dog, or by sitting where the dog lay [5, 10]. In an Australian survey, most products involved were labelled for dogs with a clear “toxic to cats” warning, and most had been bought in supermarkets [3].
Why cats? Permethrin overstimulates the nerves by slowing the closing of their sodium channels [9]. The liver clears it partly by glucuronidation, a route that works poorly in cats [6, 7]: cats have a much lower capacity to glucuronidate many substances because a key enzyme gene is not working [15]. This is the same weak point that makes acetaminophen so dangerous for cats. A 2026 review adds that metabolism is not the whole story: very concentrated dog products, a cat’s small body weight and grooming, which turns a skin exposure into an oral one, all add to the risk [14].
Signs: tremors, seizures, fever and dilated pupils
Signs usually begin within hours. In published cases, cats were already twitching or trembling when seen 30 minutes to 2 hours after a dog product was applied [6], and in another cat, signs began about 4 hours after [7].
| Sign | How often (42 cats in Sydney [2]) |
|---|---|
| Tremors or muscle twitching (fasciculations) | 86% |
| Twitches | 41% |
| Oversensitivity to touch or sound | 41% |
| Seizures | 33% |
| High temperature (fever) | 29% |
| Drooling | 24% |
| Wobbly walking (ataxia) | 24% |
| Dilated pupils | 19% |
| Temporary blindness | 12% |
In 286 cases reported to the UK Veterinary Poisons Information Service, 96.9% of cats had signs, and 87.8% had increased muscle activity: twitching, tremors or convulsions [1]. Fast breathing and a very low body temperature are also described [6, 7]. The signs last a long time: convulsions lasted on average 38.9 hours and tremors 32 hours [1].
How much permethrin is toxic to a cat?
There is no known safe amount. The minimum toxic dose is unknown; based on reported cases, about 100 mg/kg, roughly 1 mL of a 45% product on a 4 to 5 kg cat, can cause life-threatening poisoning, and lower amounts are expected to be enough [6]. French authorities warn that with concentrated pipettes, a few drops can be enough to cause severe effects in the most sensitive animals [11]. The amount applied does not reliably predict how ill the cat will be [6]. Call your vet or a pet poison line whatever the amount.
What the vet checks, and why
The diagnosis rests mainly on the story of exposure and the typical signs [4, 9]. Permethrin can be measured in body tissues and fluids, but it leaves no characteristic lesions [9], so in practice the vet treats on the history. Blood and chemistry panels are usually normal, apart from stress changes such as a high blood sugar and high neutrophils [6]. The tests look for complications and help monitor the cat.
- Abbreviation GLU or glucose, often measured first in an emergency, with the PCV and total protein [7].
- Result 291 mg/dL is the value reported in one cat with permethrin poisoning [6]: high, as stress raises blood sugar in cats.
- Unit mg/dL in the United States, mmol/L in Europe: 291 mg/dL ≈ 16.2 mmol/L.
- Laboratory interval The example uses the cat interval of the Merck Veterinary Manual [13]; each laboratory sets its own.
- Flag H: above the interval. In permethrin poisoning this is usually a stress response [6]; after long seizures the vet also watches for a low value [7].
| Check | What can be found | Why it matters |
|---|---|---|
| Body temperature | High (29% of cats) or, later, low (29%) [2] | A high temperature is common at presentation; a low temperature was the most common complication in the Sydney study [2] |
| Blood glucose | Often high from stress; low after long seizures | Stress hyperglycemia is common [6]; hypoglycemia is a possible complication of prolonged seizures [7] |
| Electrolytes | Abnormal in some cats | Electrolyte problems occurred in 26% of cats [2]; fluids are used to keep them balanced [6] |
| CK (creatine kinase) | Can rise with muscle injury | CK leaks from damaged muscle; a rise shows muscle injury but not its cause [12] |
| Kidney values and urine | Usually normal; watched in cats with long seizures | Long-lasting seizures can release myoglobin from muscle into the urine, which may injure the kidneys [6, 12] |
| PCV and total protein | Part of the basic emergency check | Used as a minimum database in cats with permethrin poisoning [7]; low protein and anemia were uncommon complications [2] |
For the general layout of a feline report, see cat blood work explained.
Care and outlook: can cats recover?
Yes, most cats recover with prompt care. There is no specific antidote [9]. Treatment means washing the coat gently with a mild detergent and cool or lukewarm water, controlling tremors and seizures, fluids and supportive care [6, 9]. Some vets also give an intravenous lipid infusion: in a randomized trial of 34 cats, cats that received it improved earlier than cats given saline [8].
Recovery typically takes 2 to 3 days, but in some cats 5 to 7 days [1]. In the UK poison-line cases, 10.5% of cats died [1]. In a Brisbane emergency clinic, 19 of 20 cats recovered, with no long-term problems at 4 months; the only death was a kitten whose treatment was delayed by 24 hours [4]. In Sydney, complications occurred in a third of cats and one of 42 was euthanized [2]. An Australian survey of vets counted 750 cases with 166 deaths over two years, including 39 cats euthanized because owners could not pay for treatment [3]. Cats treated early usually make a full recovery; cats with seizures that are hard to control have a poorer outlook [10].
Prevention: flea treatment for cats
- Never use a dog flea or tick product on a cat, not even a smaller amount [10].
- Use only products prescribed or labelled for cats, chosen with your vet; read the label and the warnings [10].
- Be careful in shops and online: dog and cat products are often displayed side by side, and some listings do not show the active ingredients [10].
- If you have dogs and cats, ask your vet about a dog treatment without permethrin. If your dog gets a permethrin product, keep the cat away: until the spot is dry and cannot be licked, according to French authorities [11], or for 72 hours, according to International Cat Care [10].
Related articles
En français : perméthrine et chat.
Questions to ask your veterinarian
- Has all the product been washed off, or should the coat be washed again?
- Is my cat’s temperature normal now, and how often will it be checked?
- Is the blood glucose high from stress, or low after the seizures?
- Are the electrolytes, CK and kidney values normal?
- Which flea treatment is right for my cat, and for my dog if they live together?
Get your cat’s emergency blood results explained.
AI DiagAnimals reads the glucose, electrolytes, CK and kidney values together with your laboratory’s intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
Is permethrin toxic to cats after it dries?
No source shows that a dried product is safe for cats. French authorities advise keeping a treated dog away from cats until the application site is dry and making sure the cat cannot lick it [11]; International Cat Care advises keeping them apart for 72 hours [10]. Permethrin stays in the skin and coat of the treated animal, where it can be passed on by contact and grooming [14]. Ask your vet before letting them back together.
Can I use permethrin if I have a cat?
Never on the cat. For a dog that lives with a cat, International Cat Care advises choosing a dog flea treatment without permethrin, or keeping the animals apart for 72 hours if one is used [10]. Choose flea products for both pets with your vet.
How much permethrin is toxic to cats?
There is no known safe amount. The minimum toxic dose is unknown; about 100 mg/kg, roughly 1 mL of a 45% product on a 4 to 5 kg cat, can be life-threatening, and less is expected to be enough [6]. With concentrated pipettes, a few drops can suffice [11]. Call your vet or a pet poison line whatever the amount.
How long does it take for permethrin to be safe for cats?
For a treated dog in the same home, advice ranges from until the application site is dry and cannot be licked [11] to 72 hours [10]. For a poisoned cat, tremors last on average 32 hours and recovery usually takes 2 to 3 days, sometimes 5 to 7 [1].
Can cats recover from permethrin poisoning?
Yes, most do with prompt treatment. In a Brisbane clinic, 19 of 20 cats recovered with no long-term problems at 4 months [4]; in UK poison-line cases, 10.5% died [1]. Cats with seizures that are hard to control have a poorer outlook, so call your vet straight away [10].
Sources
- Sutton NM, Bates N, Campbell A. Clinical effects and outcome of feline permethrin spot-on poisonings reported to the Veterinary Poisons Information Service (VPIS), London. J Feline Med Surg. 2007;9(4):335-339. doi.org/10.1016/j.jfms.2007.05.003
- Boland LA, Angles JM. Feline permethrin toxicity: retrospective study of 42 cases. J Feline Med Surg. 2010;12(2):61-71. doi.org/10.1016/j.jfms.2009.09.018
- Malik R, Ward MP, Seavers A, et al. Permethrin spot-on intoxication of cats: literature review and survey of veterinary practitioners in Australia. J Feline Med Surg. 2010;12(1):5-14. doi.org/10.1016/j.jfms.2009.12.002
- Dymond NL, Swift IM. Permethrin toxicity in cats: a retrospective study of 20 cases. Aust Vet J. 2008;86(6):219-223. doi.org/10.1111/j.1751-0813.2008.00298.x
- Linnett PJ. Permethrin toxicosis in cats. Aust Vet J. 2008;86(1-2):32-35. doi.org/10.1111/j.1751-0813.2007.00198.x
- Ceccherini G, Perondi F, Lippi I, Grazia G, Marchetti V. Intravenous lipid emulsion and dexmedetomidine for treatment of feline permethrin intoxication: a report from 4 cases. Open Vet J. 2015;5(2):113-121. pubmed.ncbi.nlm.nih.gov/26623376
- Di Pietro S, Falcone A, Arfuso F, et al. Treatment of permethrin toxicosis in cats by intravenous lipid emulsion. Toxics. 2022;10(4):165. doi.org/10.3390/toxics10040165
- Peacock RE, Hosgood G, Swindells KL, Smart L. A randomized, controlled clinical trial of intravenous lipid emulsion as an adjunctive treatment for permethrin toxicosis in cats. J Vet Emerg Crit Care. 2015;25(5):597-605. doi.org/10.1111/vec.12322
- Gupta RC, Doss RB. Plant-Derived Insecticide Toxicosis in Animals (pyrethrins and pyrethroids). Merck Veterinary Manual, reviewed 2022, updated 2024. merckvetmanual.com/toxicology/insecticide-and-acaricide-organic-toxicity/plant-derived-insecticide-toxicosis-in-animals
- International Cat Care. Permethrin poisoning. Updated 2025. icatcare.org/articles/permethrin-poisoning
- Anses. L’Anses rappelle de ne pas traiter les chats avec les médicaments antiparasitaires pour chiens à base de perméthrine. Press release, 7 May 2019 (in French). anses.fr/fr/system/files/PRES2019CPA08.pdf
- eClinPath (Cornell University). Creatine kinase. eclinpath.com/chemistry/muscle/creatine-kinase
- Merck Veterinary Manual. Serum biochemical analysis reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/serum-biochemical-analysis-reference-ranges
- Britti D, Castagna F, Bava R. Permethrin in companion animals: mechanistic neurotoxicity, dermal pharmacokinetics, and secondary exposure pathways. Toxicol Lett. 2026;422:111928. doi.org/10.1016/j.toxlet.2026.111928
- Court MH, Greenblatt DJ. Molecular genetic basis for deficient acetaminophen glucuronidation by cats: UGT1A6 is a pseudogene. Pharmacogenetics. 2000;10(4):355-369. doi.org/10.1097/00008571-200006000-00009
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.