💊 My Dog Ate Tylenol or Paracetamol. Is It Toxic?
Paracetamol (acetaminophen, Tylenol, Panadol, Calpol) is used in dogs by vets at careful doses, which is why some owners think a tablet is harmless. Above about 100 mg/kg it damages the liver, and above 200 it stops red blood cells carrying oxygen: brown gums, swollen face and paws, and fast breathing. Cats have no safe dose at all. Work out the mg per kilo, and call.
Paracetamol / Tylenol dose checker
Your dog's weight plus what went in gives the dose per kilo and the urgency. Estimating? Assume the worst case.
How much paracetamol is toxic?
| Species and dose | Effect | Example |
|---|---|---|
| Dogs, above about 100 mg/kg | Liver damage (necrosis) over 1 to 3 days | Two 500 mg tablets for a 10 kg dog |
| Dogs, above about 200 mg/kg | Methaemoglobinaemia: blood cannot carry oxygen; brown gums, swelling of face and paws | Four 500 mg tablets for a 10 kg dog |
| Cats, 10 mg/kg (some references 40 to 50) | Methaemoglobinaemia within hours; often fatal | A fraction of one tablet |
Vets do prescribe paracetamol to dogs (roughly 10 to 15 mg/kg), which is why the safety margin looks generous, but tablets are sized for adult humans and small dogs cross the line quickly. Cats lack the enzyme that detoxifies it and must never be given it. Cold and flu combination products add decongestants and antihistamines that are toxic on their own.
Symptoms and timeline
| Time after eating | What you may see |
|---|---|
| 1 to 4 hours | Vomiting, drooling, dullness. At high doses: brown or muddy gums, blue tinge to lips, fast breathing, swollen face and paws, dark urine. |
| 24 to 72 hours | Liver damage: vomiting, no appetite, jaundice (yellow gums or eyes), belly pain, bleeding tendencies. |
What the vet will do
Induce vomiting if within about 2 hours, activated charcoal, then N-acetylcysteine (the antidote) by mouth or IV for 48 hours, plus liver protectants (SAMe), fluids, oxygen and blood tests for methaemoglobin and liver enzymes over 72 hours. Severe methaemoglobinaemia may need a transfusion. Early treatment gives a good outlook; established liver failure does not.
What to do right now
- Find the packet: strength (325, 500, 650 mg or liquid), how many, and whether it is a combination product.
- Call now: Pet Poison Helpline (US/CA) 855-764-7661 · ASPCA Animal Poison Control 888-426-4435 · Animal PoisonLine (UK) 01202 509000 · Ireland and elsewhere: your vet or the nearest emergency clinic. Poison lines charge a fee; they are worth it.
- Do not give another dose of any medication, and keep cats away from all paracetamol.
- Look at the gums: brown, muddy or blue means go immediately.
Paracetamol / Tylenol FAQ
How much Tylenol is toxic to a dog?
Liver damage from about 100 mg/kg and methaemoglobinaemia from about 200 mg/kg. For a 10 kg dog that is two and four extra-strength (500 mg) tablets. Any amount is a call, and cats have no safe dose.
My dog ate one Tylenol. Will it be OK?
Do the maths: 500 mg is 50 mg/kg for a 10 kg dog (close to the line, call now) and 17 mg/kg for a 30 kg dog (below it, still call and watch for 48 hours). Small dogs, puppies and dogs with liver disease need treatment at lower doses.
Can I give my dog paracetamol for pain?
Only if a vet prescribes it and sets the dose; vets use it at roughly 10 to 15 mg/kg. Never guess with human tablets, and never give it to a cat.
How long does paracetamol take to affect a dog?
Vomiting and, at high doses, brown gums and facial swelling within 1 to 4 hours; liver damage over 1 to 3 days. Do not wait for symptoms.
What is the antidote for paracetamol poisoning in dogs?
N-acetylcysteine, given for about 48 hours, plus supportive care. It works best started early, which is why the call needs to happen now rather than after signs appear.
Related
Sources: Merck Veterinary Manual, Toxicoses from Human Analgesics (dogs: signs above 100 mg/kg, methaemoglobinaemia above 200; cats: 40 to 50 mg/kg, some at 10); Pet Poison Helpline acetaminophen guidance (dogs 75 to 100 mg/kg); ASPCA Animal Poison Control Center; VCA acetaminophen toxicity client handout. Thresholds are population figures for otherwise healthy adult animals; puppies, kittens, seniors and animals with kidney, liver or heart disease can be affected at lower doses. Last reviewed August 2026.