Is Acetaminophen (Tylenol) toxic to cats?
No, never. Acetaminophen is one of the most lethal drugs a cat can be given. A single standard 500mg tablet can kill an average-sized cat. Never give acetaminophen, even in 'just a small amount'.
If your cat has just eaten acetaminophen (tylenol)
- This is a genuine emergency. Treatment is time-critical — within 2 hours of ingestion gives the best outcome.
- Do not try to induce vomiting at home — this is dangerous in cats.
- Call your vet or the nearest emergency vet immediately.
- If you can't reach a vet, call ASPCA Poison Control ((888) 426-4435) — paid triage, 24/7.
- Bring the tablet packaging with you, noting strength (usually 500mg tablets) and quantity missing.
- Use our acetaminophen dose calculator to estimate severity while you travel to the vet.
What's the full picture?
Acetaminophen (sold as Tylenol, plus generics and combination products like NyQuil and Excedrin) poisoning is one of the most common and most lethal accidental poisonings in US cats. Cats lack a liver enzyme (glucuronyl transferase) that both humans and dogs use to process acetaminophen safely. Without that enzyme, acetaminophen accumulates and is converted to a toxic metabolite (NAPQI) that destroys red blood cells and severely damages the liver.
The toxic dose in cats is extremely low — around 10mg per kg of body weight. A standard 500mg acetaminophen tablet is therefore 10–12 times the toxic dose for an average 9 lb (4 kg) cat. A half tablet is still a lethal dose.
Most acetaminophen poisonings happen when owners try to treat a cat in pain with human medication, often because they believe 'just a little bit' is safe. It is not. If your cat appears to be in pain, call your vet — there are cat-safe painkillers available on prescription.
Use our acetaminophen dose calculator below if you think your cat has had any acetaminophen. It will estimate severity based on your cat's weight and the dose. In almost every case the answer will be: go to the vet now.
This guidance reflects published US veterinary toxicology literature including AAHA (American Animal Hospital Association) references and ASPCA APCC monograph data on feline acetaminophen toxicity. Cats are exquisitely sensitive because they lack sufficient glucuronyl transferase enzyme activity to metabolize acetaminophen safely.
Symptoms to watch for
Hidden sources you might not think of
- Acetaminophen tablets (own-brand, Panadol, generic acetaminophen)
- Tylenol (acetaminophen) and other acetaminophen-based children's medicines
- Lemsip and other cold and flu sachets
- Co-codamol (acetaminophen + codeine)
- Acetaminophen dropped on the floor and found by the cat
Safer alternatives
- Vet-prescribed cat-safe painkillers (meloxicam in small controlled doses is one option for specific conditions)
- Always call your vet before giving any painkiller
Questions owners ask
My cat seems in pain. Can I give half a acetaminophen just this once?
No. Even half a tablet can be fatal. Phone your vet — they can prescribe or recommend a cat-safe painkiller. Never use any human painkiller on a cat without vet instruction.
My cat bit into a acetaminophen tablet and spat it out. What now?
Go to the vet. Even a small amount of acetaminophen absorbed through the mouth and stomach can be toxic. Bring the tablet with you and your cat's weight.
Why is acetaminophen so dangerous to cats when humans tolerate it fine?
Cats lack enough of a liver enzyme called glucuronyl transferase, which is what humans and dogs use to process acetaminophen safely. Without it, the drug is converted to a toxic byproduct that destroys red blood cells and damages the liver. The exact dose that is routine for a human adult can be fatal to a cat.
Related
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