Acetaminophen (Tylenol) Toxicity Calculator
Dog or cat got into acetaminophen (Tylenol / paracetamol)? Pick the species, enter their weight and how many tablets to see the risk — for a cat there is no safe amount, so any suspected ingestion is treated as an emergency.
Pick dog or cat above, then enter their weight and amount to see the risk.
- ASPCA Animal Poison Control: (888) 426-4435 · US (fee may apply)
- Pet Poison Helpline: (855) 764-7661 · US/Canada (fee may apply)
This is an estimate to help you decide whether to call, not a diagnosis. When the amount is uncertain or your pet is small, young or unwell, treat it as more serious and pick up the phone.
Estimate only — not veterinary advice. Every animal is different; for a medication dose, a possible poisoning, or any emergency, call your veterinarian or an animal poison control line right away.
Dogs vs cats: very different danger
Acetaminophen (Tylenol, paracetamol) harms pets in two ways: it damages the liver, and it changes hemoglobin so the blood can't carry oxygen (methemoglobinemia — the tell-tale brown or blue gums). Dogs have some ability to process it, so risk rises with dose. Cats don't— they're missing the enzyme entirely, which is why a single tablet can be fatal and why this calculator flags any amount in a cat as an emergency.
What to do right now
Time matters because the antidote (N-acetylcysteine) works best early. Note the strength and number, pick the right species above, and call your vet or a poison line (ASPCA 888-426-4435, Pet Poison Helpline 855-764-7661) right away — for a cat, go straight in. Never give acetaminophen to a pet to treat pain; your vet has safe alternatives.
Frequently asked questions
- How much Tylenol is toxic to a dog?
- For dogs, liver damage becomes a risk around 100 mg of acetaminophen per kg of body weight, with red-blood-cell damage at higher doses. A single 500 mg Extra Strength tablet can be dangerous for a small dog. Cats are a completely different story — see below.
- Is acetaminophen toxic to cats?
- Extremely. Cats lack the liver enzyme needed to process acetaminophen safely, so there is no dose anyone should give one. A single regular-strength tablet is many times the dose that has killed cats, which is why this calculator sends every suspected feline ingestion straight to “emergency” rather than showing a watch-and-wait band. It turns their blood brown (methemoglobinemia) so it can't carry oxygen. Never give a cat acetaminophen, and if one swallows any, treat it as an emergency. Switch the calculator to 'Cat' to see this.
- What are the symptoms of acetaminophen poisoning?
- Brown or blue-grey gums, trouble breathing, and a swollen face or paws (especially in cats), plus vomiting, lethargy and — over a day or two — signs of liver damage like yellow gums. Cats can show signs within hours.
- What do I do if my pet ate acetaminophen?
- Call your vet or a poison line immediately — for cats, treat any amount as an emergency. There's an antidote (N-acetylcysteine) that works best when given early, so don't wait for symptoms to appear.
Sources
These are the references behind this calculator. Where a source gives a range we take the midpoint and round toward caution, and where we go beyond what a source states — an extra safety margin, or a rule of thumb rather than a clinical threshold — the page says so in the text above.
- Acetaminophen — Pet Poison Helpline
- Acetaminophen toxicity in cats — VCA Animal Hospitals
- Animal Poison Control Center — ASPCA