Topical Medications Toxic to Cats: Creams, Gels, Patches and Spot-Ons

Several topical medications toxic to cats sit in ordinary bathroom cabinets: prescription pain creams containing flurbiprofen, which the FDA tied to the deaths of three cats, and permethrin flea spot-ons made for dogs, which International Cat Care calls one of the most common causes of cat poisoning worldwide. Fluorouracil and calcipotriene skin creams, hormone gels, nicotine patches, concentrated tea tree oil and minoxidil hair-regrowth products are dangerous too, and many of them reach a cat through its own grooming after it touches an owner’s treated skin, the bed or a recently treated dog.

The evidence behind each product is uneven. Some are well documented in cats; others are known mostly from dogs, with cats described as likely to be more sensitive. This guide keeps those apart. Minoxidil (Rogaine) has its own series of guides on this site, which is why the emergency box below names it, but the same two poison control lines take calls about every product on this page.

Topical medications toxic to cats at a glance

The table sums up each product group covered below. The last column says how strong the cat-specific evidence is, which is not the same as how dangerous the product is.

Product (example)	Main concern for cats	Documented in cats?
NSAID pain cream (flurbiprofen)	Kidney failure, stomach and gut ulcers	Yes: FDA reports and a case report
NSAID cream or gel (diclofenac)	Possible liver injury	Limited: one 2026 report, cause unproven
Salicylate rubs (methyl salicylate)	Gut ulcers, high temperature, liver injury	Limited: no cat skin-transfer case found
Skin-cancer cream (fluorouracil, 5-FU)	Seizures, severe vomiting, death	Limited: none reported to FDA
Psoriasis cream (calcipotriene)	High calcium, kidney failure	Limited: mostly dog data
Hormone gel or spray (estradiol, testosterone)	Heat-like signs, swollen mammary glands	Dogs only in reports we found
Dog flea spot-on (permethrin)	Tremors, twitching, seizures	Yes: case series
Nicotine patch, gum or e-liquid	Vomiting, agitation, tremors	Limited: mostly dogs
Tea tree oil (100%)	Drooling, weakness, wobbling, tremors	Yes: poison center data
Zinc oxide (diaper cream)	Vomiting, diarrhea; more is disputed	Limited: no cat-specific report found
Minoxidil (Rogaine)	Low blood pressure, heart failure	Yes: poison center data and case reports

How a cream on your skin ends up inside your cat

The Merck Veterinary Manual’s chapter on human topical agents, written by an ASPCA Poison Control toxicologist and last fully reviewed in June 2025, opens with a plain statement: “Exposures due to ingestion of human topical agents are common in household pets.” It lists the routes as “biting into the tubes, swallowing patches, grooming fur contaminated by transfer from human skin, or licking the applied agent off of human skin.”

Cats are especially exposed to the last two. International Cat Care points out that cats “will groom any substance off their coats and swallow it,” and Pet Poison Helpline adds that “their small size means even small amounts of hazardous items can lead to poisoning cases.” A cat that rubs its cheek on your treated wrist does not have to lick you at all; it can swallow the drug later, while washing.

Metabolism plays a part for some drugs. Merck explains cats’ sensitivity to ibuprofen this way: “Cats are especially susceptible because they have limited glucuronide conjugating capacity.” International Cat Care puts the same idea more simply: cats’ livers “are unable to break down certain chemicals.” That weakness is real, but it does not explain every case. A review of feline drug handling cautions that “the causes of these differences are poorly understood,” so it is safer to treat each product on its own evidence.

The scale is large, though the figures cover all medicines, not only skin products. The ASPCA’s annual report says “In 2025, ASPCA Poison Control received calls about over 376,000 items that pets were exposed to.” Over-the-counter medicines and supplements stayed its top category at 16.9% of exposures, with the rise partly put down to “new skin care products (masks and creams) promoted on social media.” Pet Poison Helpline says “Nearly 50% of all calls” it receives involve human medications.

Pain creams: NSAIDs and salicylates

Flurbiprofen

Flurbiprofen creams have the clearest regulator record for cats. In 2015 the FDA reported cats in two households that fell ill or died after their owners used flurbiprofen pain creams on themselves: “The pet owners had applied the cream or lotion to their own neck or feet, and not directly to the pet.” Two cats recovered from kidney failure, two in the second household died, and a third cat there died after the owner had already stopped using the cream: five cats in all, three of them dead, by our count of the FDA’s figures. A separate 2017 case report describes a cat likely exposed to an owner’s compounded cream “containing 10% flurbiprofen” that needed surgery for a perforated gut and went home after nine days. The FDA’s current advice warns that even “a slight amount left on a cloth applicator, could be dangerous to pets.”

Diclofenac

The cat evidence here is thinner, and it should be read that way. ASPCA Poison Control notes that diclofenac is sold over the counter as a topical and that “Cats are much more sensitive than dogs.” A 2026 report in the Canadian Veterinary Journal describes two cats in one home with acute liver injury, where the caregiver had used a 10% diclofenac cream for three months; one cat was euthanized, and the authors state that “direct evidence linking acute liver injury to diclofenac exposure was lacking.” They also write that “The toxic threshold of diclofenac in cats is currently unknown.” For how cats handle swallowed NSAIDs, see our page on ibuprofen and cats.

Salicylates

Salicylates are aspirin relatives found, per Merck, in “sunscreens, topical pain relievers, and topical wart removal products,” and “Oil of wintergreen contains 98% methyl salicylate.” Cats clear aspirin slowly: Merck gives its half-life in cats as 37.5 hours. A 2010 Pet Poison Helpline lecture said heat rubs can hold up to 30% methyl salicylate and that “Cats are more susceptible to toxicosis,” while adding that “overdoses from topical exposure would not be expected unless large quantities were used chronically.” We found no published cat case from licking a salicylate rub off an owner. Our guides to cats licking sunscreen and cats licking lotion off skin cover the everyday versions.

Prescription skin creams: fluorouracil and calcipotriene

Fluorouracil (5-FU)

Fluorouracil creams treat skin cancers and precancers, and the FDA has warned about them repeatedly. Its pet page reports “a total of 20 dogs, all 20 dogs died,” and states plainly: “FDA hasn’t received any reports about fluorouracil poisoning in cats.” That gap is not reassurance. The same FDA page relays Pet Poison Helpline’s view that “the prognosis for cats that ingest the medicine is grave,” and warns that a cat that gets the cream on its fur “could ingest the medicine and potentially become sick and die” while grooming. A 2020 dermatology letter describes a different route, direct application by owners, who “have been reported to apply 5-FU to suspected actinic keratoses on their cats’ ears, leading to death when the cat licked the area.”

Calcipotriene

Calcipotriene is a vitamin D-type psoriasis cream, sold as Sorilux and Dovonex among others. Pet Poison Helpline warns that “Small ingestions – even a lick or taste – by companion animals can lead to severe, chronic disturbance in electrolytes, kidney failure, and death.” The dose data come from dogs; the 2010 helpline lecture said the toxic dose “has not been reported in cats but it is well established that they are more sensitive to the effects of calcipotriene than dogs are.” Merck says signs usually appear 24 to 36 hours after ingestion, and ASPCA Poison Control notes that once signs develop, “sometimes weeks to months of treatment are required.”

Hormone gels, creams and sprays

In June 2026 the UK’s Veterinary Medicines Directorate warned that “pets may absorb oestrogen or testosterone by coming into contact with areas of human skin where hormone gels and creams have been applied,” noting that forearms, a commonly recommended application site, are also what we stroke and cuddle pets with. Exposed females “may show signs similar to being in heat, such as vaginal bleeding and a swollen vulva,” and males “can develop swollen mammary glands and a change in testicular size.” It also tells owners not to stop their own prescribed treatment, even if a pet shows signs of exposure.

Be clear about species here. The regulator writes about pets in general, and the published animal cases we found are dogs: the FDA’s 2010 review of the estradiol spray Evamist covered “two spayed female dogs” exposed by licking an owner’s arm or being held, and a 2015 report described six dogs from three households that lost hair after contact with their owners’ hormone replacement products. We found no published cat case, which is a gap in the record rather than evidence that cats are spared.

Dog flea spot-ons: permethrin

Permethrin is the clearest case on this page. International Cat Care says it “is highly toxic to cats, but it remains one of the most common causes of poisoning in cats worldwide.” In an Australian review of 42 cats, most had been given a dog spot-on directly by their owners, and tremors or muscle twitching appeared in 86%. The same insecticide is also sold for human head lice, according to Cornell’s veterinary pharmacy.

A cat can also be poisoned by the dog. Australian regulator data showed cats at risk “from grooming or being in direct contact with recently treated dogs,” and International Cat Care notes that permethrin can move to a cat’s coat when it “rubs against a dog, or even sits on the same furniture.” In 2010 the US EPA called “the exposure of cats to some dog products” a concern and announced it would require clearer labels separating dog and cat products.

The sources differ on how long to keep the animals apart. International Cat Care’s advice is to “keep your dog and cat apart for 72 hours” after a permethrin product. Cornell’s Feline Health Center says “Cats must not be allowed to come in contact with a treated dog for 24 hours.” Neither source explains its number, so ask your vet which applies to your dog’s product. More on flea products is in our page on flea shampoo and cats.

Nicotine patches, tea tree oil and zinc oxide

Nicotine

For patches, the documented route is the mouth: Merck says “Pets become exposed through either chewing or complete ingestion,” and the 2010 helpline lecture warns that “even used patches still contain some amount of nicotine.” Most recorded cases are dogs, but Pet Poison Helpline says nicotine liquid “is toxic to cats as well,” and the lecture noted that “Lethal dose data has not been reported in cats.” The two sources read differently on home care: Merck, writing for vets, says patients “can be monitored at home unless they develop clinical signs,” while Pet Poison Helpline tells owners that home care “is not generally possible with nicotine exposure.” Either way, the decision follows a call.

Tea tree oil

Tea tree oil is usually put on pets deliberately. In ASPCA poison center records analyzed by Khan and colleagues in 2014, 106 cats and 337 dogs were exposed to 100% oil, and in 89% of the animals it had been applied intentionally. Signs “developed within 2 to 12 hours and lasted up to 72 hours,” and “Younger cats and those with lighter body weight were at greater risk of developing major illness.” Diluted products “do not typically lead to toxicity,” per the 2010 lecture, but Pet Poison Helpline is firm that “concentrated essential oils should never be directly applied to cats.” See our guide to essential oils and cats.

Zinc oxide

Zinc oxide is the active part of many diaper rash creams and some sunscreens, and the two versions of the Merck Veterinary Manual disagree about it. The professional chapter expects a single swallow to cause gastric irritation, vomiting and diarrhea within two to four hours, with red blood cell damage mainly when a cream is licked off a pet’s own skin “over the course of days to weeks.” The pet-owner page, last fully reviewed in 2020, says ingestion “usually results in vomiting, diarrhea, and liver and kidney damage.” Pet Poison Helpline’s main concern is gut irritation, though its page is written about dogs; we found no cat-specific report.

Minoxidil hair-regrowth products

Minoxidil is the topical drug with the most cat data. In ASPCA Poison Control records, cats were most often exposed while the owner was using it, by licking skin or a pillowcase or being splashed by a spill, and “Death occurred in 8/62 (12.9%) cats that developed clinical signs.” The ASPCA says “Cats are more sensitive to the effects of minoxidil than dogs.” Our main guide to minoxidil and cats covers the poison center data and case reports, using minoxidil with cats follows the drug room by room through a home, and if your cat licked minoxidil covers the first hour.

House rules for any topical medicine in a home with a cat

The products above differ, but the advice from regulators and poison centers converges on a short list.

• Store it shut away. The FDA warns that for pets that jump and climb, “kitchen and bathroom counters, shelves, and other high places may not be secure enough,” and that “medication containers that are child safe may not be pet safe.” Its own example of a tube that can kill a pet that chews it is fluorouracil cream.
• Apply it where the cat is not, and wash your hands. The VMD’s steps for hormone products start with keeping pets away from freshly treated skin and washing your hands with soap and water.
• Cover the treated skin. The VMD suggests covering the site “with clean clothing (such as a t-shirt) once the product has dried,” and the FDA tells flurbiprofen users to ask their health care provider whether covering is appropriate.
• Do not let your cat lick or groom treated skin. Pet Poison Helpline’s wording for 5-FU applies to all of them: “Do not allow your pet to lick where you have applied 5-FU.”
• Clear away applicators and residue. The FDA asks 5-FU users to throw away or wash gloves and swabs, and to “Avoid leaving any medicine residue on your hands, clothing, carpeting, or furniture.”
• Separate pets after a dog flea treatment, for the period your vet gives you, and never put a dog product on a cat.
• Never put a human medicine on your cat unless a vet has told you to, and never apply a concentrated essential oil to a cat at all.

If your cat does lick, groom or chew any of these, call before doing anything else and keep the tube or box beside the phone. Compounded creams can be complicated: ASPCA Poison Control notes that “Often there are three or more of these ingredients present in any particular cream,” which is why it asks vets to have owners “bring the packaging in along with the pet so a full ingredient list can be obtained.”

Frequently Asked Questions

Is diclofenac gel toxic to cats?

It may be, but the evidence is thin. Diclofenac is sold over the counter as a topical, and ASPCA Poison Control says cats are much more sensitive to it than dogs. The only cat report we found, published in 2026, describes two cats with liver injury in a home where a 10% diclofenac cream was used for three months, and its authors say direct proof that diclofenac caused it was lacking. Keep your cat off the treated skin and call a vet if it licks the area.

Can my cat get sick from my pain cream if it only sleeps next to me?

Possibly. In the FDA flurbiprofen reports, owners had put the cream on their own neck or feet, never on the cats, and nobody knows exactly how the cats were exposed. The Merck Veterinary Manual says cats can be poisoned by grooming fur that has touched treated skin. Ask your doctor whether to cover the treated area, and keep the cat off the bed while you use the cream.

Can I put my dog’s flea treatment on my cat if I use less?

No. International Cat Care says some owners assume a smaller amount of a dog product will be fine on a cat, and it is not: a tiny quantity of permethrin is enough to cause serious illness. In an Australian series of feline permethrin cases, most cats had been given a dog spot-on directly. Use only products labeled for cats.

Are diaper rash creams toxic to cats?

They are a hazard, but sources disagree on how serious one swallow is. Many contain zinc oxide. The professional Merck manual expects mainly vomiting and diarrhea from a single ingestion, with more serious red blood cell damage after repeated licking over days to weeks; the Merck pet-owner page also lists liver and kidney damage. Call your vet or a poison line if your cat eats some.

What should I bring to the vet after my cat licks a medicated cream?

Bring the tube, box or pharmacy label. Compounded pain creams often contain three or more active ingredients, and ASPCA Poison Control asks vets to have owners bring the packaging so the full ingredient list is known. Note roughly how much your cat could have licked and when.

Sources

1. Toxicosis in Animals From Human Topical Agents — Merck Veterinary Manual (Professional Version), Laura Stern, DVM, DABVT, full review June 2025; read October 8, 2026
2. FDA Warns of Illnesses and Deaths in Pets Exposed to Prescription Topical Pain Medications Containing Flurbiprofen — U.S. Food and Drug Administration, Center for Veterinary Medicine (Internet Archive copy), April 17, 2015
3. FDA Consumer Advice on Pet Exposure to Prescription Topical Pain Medications Containing Flurbiprofen — U.S. Food and Drug Administration, content current as of 02/25/2025; read October 8, 2026
4. Topical flurbiprofen toxicosis in a cat — Journal of Veterinary Emergency and Critical Care, 2017
5. Potential acute hepatic injury in 2 cats exposed to topical human diclofenac — Canadian Veterinary Journal, 2026
6. Topical Creams and Pets: A Dangerous Combination — ASPCApro (ASPCA Poison Control), undated; read October 8, 2026
7. Topical Toxic Titans…and How to Treat Them! — Pet Poison Helpline (Ahna Brutlag, DVM), 82nd Western Veterinary Conference, 2010
8. Toxicoses From Human Analgesics in Animals — Merck Veterinary Manual (Professional Version), Tyne Hovda, DVM, last updated May 2025; read October 8, 2026
9. Don’t Expose Pets to Prescription Topical Fluorouracil Medicine for People — U.S. Food and Drug Administration, Center for Veterinary Medicine, content current as of 11/22/2024; read October 8, 2026
10. Effect of topical dermatologic medications in humans on household pets — Proceedings (Baylor University Medical Center), 2020
11. 5-Fluorouracil Toxicosis in Cats and Dogs — Pet Poison Helpline, undated; read October 8, 2026
12. Calcipotriene — Pet Poison Helpline, undated; read October 8, 2026
13. FDA Drug Safety Communication: Ongoing safety review of Evamist (estradiol transdermal spray) and unintended exposure of children and pets to topical estrogen — U.S. Food and Drug Administration (Internet Archive copy), July 29, 2010
14. Topical hormone treatments: pet owners warned of risks to pets from accidental exposure — Veterinary Medicines Directorate (GOV.UK), 11 June 2026; read October 8, 2026
15. Canine alopecia secondary to human topical hormone replacement therapy in six dogs — Journal of the American Animal Hospital Association, 2015
16. Permethrin Poisoning — International Cat Care, updated 26 September 2025; read October 8, 2026
17. Common Cat Hazards — Cornell Feline Health Center, Cornell University College of Veterinary Medicine, undated; read October 8, 2026
18. Small Animal Toxins — Cornell University Hospital for Animals Pharmacy, undated; read October 8, 2026
19. Feline permethrin toxicity: retrospective study of 42 cases — Journal of Feline Medicine and Surgery, 2010
20. Permethrin toxicosis in cats — Australian Veterinary Journal, 2008
21. EPA to Increase Restrictions on Flea and Tick Products — U.S. Environmental Protection Agency (news release archive), March 17, 2010
22. E-Cigarettes and Pets Do Not Mix — Pet Poison Helpline, undated; read October 8, 2026
23. Concentrated tea tree oil toxicosis in dogs and cats: 443 cases (2002-2012) — Journal of the American Veterinary Medical Association, 2014
24. Tea Tree Oil Poisoning — Pet Poison Helpline, undated; read October 8, 2026
25. Essential Oils and Cats — Pet Poison Helpline, undated; read October 8, 2026
26. Poisoning from Human Over-the-Counter Drugs — Merck Veterinary Manual (Pet Owner Version), last updated May 2026; read October 8, 2026
27. My Dog Ate Diaper Rash Ointment. Will They Be Okay? — Pet Poison Helpline, undated; read October 8, 2026
28. The Top 10 Toxins of 2025 — ASPCA Poison Control, March 15, 2026; read October 8, 2026
29. Top 10 Human Medications Poisonous to Pets — Pet Poison Helpline, undated; read October 8, 2026
30. Cats and poisons — International Cat Care, updated 26 September 2025; read October 8, 2026
31. What To Do If Your Cat Eats Poison — Pet Poison Helpline, undated; read October 8, 2026
32. Feline drug metabolism and disposition: pharmacokinetic evidence for species differences and molecular mechanisms — Veterinary Clinics of North America: Small Animal Practice, 2013
33. Properly Store Medications to Keep Your Pet Safe — U.S. Food and Drug Administration, Center for Veterinary Medicine, content current as of 06/14/2024; read October 8, 2026
34. Topical Minoxidil Exposures and Toxicoses in Dogs and Cats: 211 Cases (2001-2019) — Journal of the American Animal Hospital Association, 2021
35. Minoxidil and Pets: What You Need to Know — ASPCA, February 26, 2026; read October 8, 2026

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This article is general information for cat owners, written from the published veterinary literature and poison control guidance listed above. It is not a diagnosis or a treatment plan for your cat. If you think your cat has been exposed to minoxidil or any other medication, contact a veterinarian or an animal poison control center straight away. Rogaine is a registered trademark of its owner; Cat Professor is not affiliated with any drug maker.