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?
Treatment works best when started early, often before any signs appear. If the tablets were eaten recently, vets commonly induce vomiting and give activated charcoal, then use stomach protectants and IV fluids. Severe cases may need treatment for an acid imbalance. There is no antidote for aspirin, so early decontamination matters.
Go straight to an emergency vet if…
- Your pet is vomiting (especially blood), panting hard, weak, wobbly, very hot, or having a seizure
- Your cat ate any aspirin
- The estimated dose is in the Emergency range
- Your pet is older, has kidney, liver, or stomach problems, or also takes another NSAID or a steroid
Call poison control first if…
- Your dog just ate the tablets and seems normal
- You are unsure of the tablet strength or how many were eaten
- The product was a combination medicine (Excedrin, some cold and migraine products) or a salicylate cream, Pepto-Bismol, or oil of wintergreen
- You want a case number and treatment plan to hand to your vet
How aspirin poisoning develops
Aspirin blocks the prostaglandins that protect the stomach lining and also affects platelets, so bleeding can be prolonged. At high doses it disrupts how cells make energy, which can cause fever, fast breathing, and a serious acid imbalance. Aspirin is absorbed quickly; blood levels peak about 0.5 to 3 hours after ingestion (Merck Veterinary Manual).
Stomach and gut signs
- Vomiting, sometimes with blood
- Loss of appetite, listlessness, weakness
- Dogs may vomit within about 2 hours
Higher doses: whole-body effects
- Fast or heavy breathing, panting, fever
- Acid imbalance found on bloodwork
- Seizures or coma after very large doses
Ulcer and bleeding complications
- Black, tarry stool or pale gums
- Prolonged bleeding from small wounds
- Liver injury in some severe cases
Published case data behind these estimates
These figures come from the Merck Veterinary Manual and a veterinary critical care textbook chapter on salicylate toxicity. Sources agree that the exact toxic dose of aspirin is not clear and varies between individual animals, so this calculator uses the lowest reported levels as its cutoffs. They describe documented clinical effects, not a line between "safe" and "dangerous."
| Aspirin dose | Documented clinical effect |
|---|---|
| Dogs: 50 mg/kg | Stomach and gut signs alone may occur (Small Animal Critical Care Medicine, Salicylates chapter). At 50 mg/kg every 12 hours, dogs vomited about 2 hours after each dose (IVIS Veterinary Toxicology). |
| Dogs: 100 to 500 mg/kg | Severe signs of toxicity reported across this wide range; toxicity may result from an acute ingestion of 100 mg/kg (Small Animal Critical Care Medicine) |
| Dogs: 450 mg/kg | A single ingestion can cause stomach upset, high body temperature, panting, seizures, or coma (Merck Veterinary Manual) |
| Dogs: 25 to 50 mg/kg, repeated | Stomach erosions and ulcers developed with repeated dosing over days to weeks (Merck Veterinary Manual) |
| Cats: over 50 mg/kg | Toxicosis may occur; any exposure over 100 mg/kg should be considered serious and potentially lethal (Small Animal Critical Care Medicine). Cats have reacted to much smaller repeated doses (Merck Veterinary Manual). |
This calculator uses, for dogs: under 50 mg/kg = contact a professional now; 50 to under 100 mg/kg = Urgent; 100 mg/kg and above = Emergency. If your dog is older, has kidney, liver, or stomach problems, or takes another NSAID or a steroid, any dose of 50 mg/kg or more is shown as Emergency. For cats, any amount is shown as Emergency, because no precise safe threshold has been published and cats clear aspirin very slowly. There is no published acute dose below which aspirin is known to cause no harm, so even the lowest result still says to call.