Medication safety · 2 min read

Is Topical creams (5-FU, calcipotriene, hormone creams) toxic to cats?

No — dangerous

No. Some prescription creams — fluorouracil (5-FU) for skin cancer, calcipotriene for psoriasis, and hormone creams (HRT, testosterone) — are severely toxic to cats who lick them from human skin.

If your cat has just eaten topical creams (5-fu, calcipotriene, hormone creams)

  1. Wipe any visible cream from the cat's fur or mouth.
  2. Call your vet immediately — these exposures are high-risk even from small amounts.
  3. If you can't reach your vet, call ASPCA Poison Control ((888) 426-4435) — paid triage, 24/7.
  4. Bring the prescription tube or a photo of the ingredients.

What's the full picture?

5-fluorouracil (5-FU, trade names Efudix and Fluoroplex) is used for certain skin cancers. A single lick from a treated skin area has caused feline deaths. Symptoms appear within hours — seizures, vomiting, bloody diarrhea.

Calcipotriene (Dovonex) is used for psoriasis. A small amount licked can cause life-threatening rises in calcium.

Hormone creams (HRT, testosterone gels) can cause significant endocrine disturbance in pets exposed to them — keep cats away from recently applied hormone creams.

If you use any prescription topical, wash hands thoroughly after application, cover the treated area, and don't let a cat lick or rub against it.

Symptoms to watch for

0–4 hours
Drooling, vomiting, tremors (for 5-FU). Rapid breathing, weakness (for calcipotriene).
4–24 hours
Seizures (5-FU), severely raised blood calcium (calcipotriene).
24–72 hours
Multi-organ failure possible without treatment.

If you're worried right now

Call your vet or out-of-hours emergency vet first. For poison advice, ASPCA Animal Poison Control (US) is on (888) 426-4435 — 24/7, charges apply. Your vet can also call the ASPCA Animal Poison Control Center (ASPCA APCC) directly.

Diclofenac (Voltarol) no Essential oils no Fish oil / omega-3 supplements caution Ibuprofen no Vitamin D supplements (cholecalciferol) no

About this guidance

Every entry on this site is compiled from published US veterinary toxicology sources — AAFP, ASPCA Animal Poison Control Center (ASPCA APCC) references, AVMA-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 US 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 ASPCA Poison Control on (888) 426-4435 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 Cat Ate It editorial team

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