How this is calculated
Dose in mg/kg = milligrams per tablet × number of tablets ÷ body weight in kg. The result is compared with the single-dose levels below. Where sources give a range, the calculator uses the lower number.
| Ibuprofen, dogs | What is reported |
|---|---|
| From 25 mg/kg | Vomiting, diarrhea, nausea, abdominal pain, loss of appetite; stomach ulcers |
| From 100 to 175 mg/kg | Acute kidney injury, bleeding from the gut; 100 used here |
| From 400 mg/kg | Seizures, wobbliness, coma |
| About 600 mg/kg | Minimum lethal dose |
| Ibuprofen, cats | What is reported or estimated |
|---|---|
| Any amount | No safe dose known; cats are thought to be about twice as sensitive as dogs |
| From about 12.5 mg/kg | Stomach injury (half the dog dose, estimated) |
| From 50 mg/kg | Severe signs, acute kidney injury and death reported |
| From about 200 mg/kg | Neurological signs (half the dog dose, estimated) |
| Naproxen, dogs | What is reported |
|---|---|
| From 5 to 7 mg/kg | Stomach irritation and ulcers; 5 used here |
| From 10 to 25 mg/kg | Kidney injury; 10 used here |
| Above 50 mg/kg | Neurological signs |
No toxic dose of naproxen has been published for cats. They clear it poorly and may be more susceptible than dogs, so the calculator treats any amount as an emergency.
What the estimate cannot tell you
- Repeated doses add up: dogs given ibuprofen at 8 mg/kg a day for 30 days developed stomach ulcers, and lower repeated doses have caused fatal perforation.
- Kidney disease, dehydration, low blood pressure or steroid medication raise the risk.
- Kidney injury has been reported in cats that ate only part of a 400 mg tablet.
- Combination products (for example with a decongestant) add their own risks. Acetaminophen (Tylenol) is not an NSAID and is not covered here; it is extremely dangerous to cats. See who to call for a pet poisoning.
Sources
- E. Dunayer, “Ibuprofen toxicosis in dogs, cats, and ferrets,” Toxicology Brief, Veterinary Medicine, July 2004, ASPCA Animal Poison Control Center. Dose table for dogs, cats twice as sensitive, tablet strengths, repeated-dose findings.
- Merck Veterinary Manual, “Toxicoses From Human Analgesics in Animals,” T. Hovda; full review July 2024, updated May 2025. Ibuprofen doses, cats at about half the dog dose, naproxen findings.
- E. M. Butty and others, “Outcomes of nonsteroidal anti-inflammatory drug toxicosis treated with therapeutic plasma exchange in 62 dogs,” Journal of Veterinary Internal Medicine, 2022. Toxic dose definitions for ibuprofen and naproxen.
- Y. Herrero and others, “Acute nephrotic-range glomerular proteinuria following ibuprofen intoxication in two cats,” Journal of Feline Medicine and Surgery Open Reports, 2022. 50 mg/kg in cats; kidney injury after part of a tablet.
- “Naproxen Toxicosis in an Elderly Greyhound,” Clinician’s Brief, February 2012, citing ASPCA Animal Poison Control Center data; C. DeClementi, “Naproxen toxicosis in dogs,” dvm360, 2013. Naproxen doses in dogs.
Reviewed November 2026. This calculator gives an estimate, not a diagnosis, and does not replace a veterinarian. Published doses come from case reports and poison-center experience; individual animals differ.