Assess the situation
Fill in what you know. Estimates are fine, exact numbers are better. Keep the packaging nearby for your call.
Emergency vet or poison control: which do I call?
An antidote (acetylcysteine) and supportive care work best when started early, before signs appear.
Go straight to an emergency vet if…
- The pet is a cat, regardless of amount
- Your pet has brown or muddy-colored gums, trouble breathing, a swollen face or paws, or is weak
- The estimated dose for your dog is in the Emergency range
- Poison control or your vet has told you to come in
Call poison control first if…
- Your dog just ate the tablets and seems normal
- You are unsure of the strength or how many were eaten
- The product was a combination medicine with other ingredients
- You want a case number to hand to your vet
How acetaminophen poisoning develops
Acetaminophen damages red blood cells (methemoglobinemia, which reduces oxygen delivery) and the liver. Cats mostly develop blood changes; dogs more often develop liver injury.
Blood changes (especially cats)
- Brown or muddy gums
- Fast or labored breathing
- Weakness, lethargy
- Swelling of the face or paws
Liver injury (especially dogs)
- Vomiting, loss of appetite
- Abdominal pain
- Liver values rise on bloodwork
Advanced signs
- Yellow gums or eyes (jaundice)
- Collapse
- Death without treatment in severe cases
Published case data behind these estimates
These figures come from the Merck Veterinary Manual and an ASPCA Animal Poison Control Center review. They describe documented clinical thresholds, not a line between "safe" and "dangerous."
| Dose | Documented clinical effect |
|---|---|
| Cats: 10 mg/kg | Clinical signs reported in some cats; no safe dose for cats |
| Cats: 40–50 mg/kg | Toxicosis generally occurs |
| Dogs: > 100 mg/kg | Clinical signs, liver injury possible |
| Dogs: > 200 mg/kg | Methemoglobinemia reported |
This calculator uses: cats = Emergency at any amount. Dogs: under 50 mg/kg = contact a professional now; 50 to under 100 mg/kg = Urgent (a conservative safety margin below the 100 mg/kg threshold, since repeated doses and individual sensitivity lower the toxic dose; this margin is our choice, not a published cutoff); 100 mg/kg and above = Emergency.