Emergency? Call now - do not wait for symptoms.
Is Naproxen (Aleve) toxic to dogs or cats?
Category: Medication | Last reviewed: June 2026
Quick verdict
Dogs
EMERGENCYCats
EMERGENCYNaproxen (Aleve) and dogs
Naproxen has a far narrower margin of safety in dogs than in humans. Signs of toxicity have been reported at doses as low as 5 mg/kg, and a single 220 mg Aleve tablet can cause serious harm even in a large dog. Stomach and intestinal ulcers (which can perforate) and acute kidney failure are the primary risks. There is no safe at-home dose - it is longer-acting and more dangerous than ibuprofen.
Onset
1-4 hours; kidney signs may take 12-24 hours
Symptoms
- - vomiting
- - bloody vomiting
- - black tarry stools
- - diarrhoea
- - abdominal pain
- - loss of appetite
- - pale gums
- - lethargy
- - kidney failure
- - seizures at high doses
What to do now
Emergency. Call ASPCA Poison Control (888-426-4435) or rush to an emergency vet. Early decontamination is critical. Bring the packaging - the dose per kg of body weight determines the risk.
Toxicity is dose-dependent. Your dog's weight and the quantity consumed are both important - include these when you call poison control.
Naproxen (Aleve) and cats
Cats are even more sensitive to NSAIDs than dogs and cannot metabolise them safely. Even a fraction of a tablet can cause life-threatening GI ulceration and kidney failure.
Onset
1-2 hours
Symptoms
- - vomiting
- - abdominal pain
- - loss of appetite
- - kidney failure
- - weakness
- - seizures
What to do now
CRITICAL EMERGENCY. Rush to an emergency vet immediately. Call ASPCA Poison Control (888-426-4435) en route.
Data sources
- - ASPCA Animal Poison Control
- - Pet Poison Helpline - Naproxen
- - Merck Veterinary Manual
Last reviewed: June 2026
Data error? Email data@treatortoxic.com with a source reference.