Ibuprofen and painkiller toxicity calculator for dogs

Why are human painkillers dangerous for dogs?

Ibuprofen, naproxen and aspirin are nonsteroidal anti-inflammatory drugs (NSAIDs). They work by blocking enzymes that make prostaglandins, and some prostaglandins do protective jobs: they limit stomach acid, keep blood flowing to the stomach lining and help it repair, and keep blood flowing through the kidneys. Block them hard enough and the result is stomach ulcers, bleeding and kidney failure.

Dogs handle some of these drugs very differently from people. Naproxen, for example, lasts about 74 hours in a dog because it is recycled through the liver and gut. Acetaminophen is not an NSAID; in dogs, overdoses mainly damage the liver and, at higher doses, stop red blood cells carrying oxygen properly.

Toxic doses of ibuprofen, naproxen, acetaminophen and aspirin

These are the levels the calculator uses, in milligrams of drug per kilogram of body weight. Where veterinary sources disagree, it uses the lower number so it doesn't understate the risk.

The ibuprofen kidney figure is the one sources disagree on most: one toxicology review puts it at over 125 mg/kg, an ASPCA brief at over 175 mg/kg, and Merck at 175 to 300 mg/kg. The calculator uses 125.

How many tablets are dangerous for my dog?

Number of standard tablets that reach each level, by dog weight. Fractions are real: a quarter of a tablet can matter for a small dog.

Naproxen stands out: a single 220 mg Aleve tablet is past the ulcer level for any dog under about 69 lb. Pet Poison Helpline warns that one tablet can cause very serious problems even in a large dog.

Watch out for combination products

Many painkillers share a box with other drugs, and the second drug can be the bigger problem. The calculator flags these when you pick them:

• Cold and sinus versions (Advil Cold & Sinus, Aleve-D) contain pseudoephedrine. In dogs it causes signs from 5 to 6 mg/kg and can kill at 10 to 12 mg/kg, so one 120 mg extended-release tablet can be life-threatening for a 20 lb dog.
• PM versions (Advil PM, Tylenol PM) add diphenhydramine, the sedating antihistamine in Benadryl. The Benadryl dosage calculator explains that drug.
• Excedrin combines acetaminophen, aspirin and caffeine. Run the calculator for acetaminophen and for aspirin, and count the caffeine like chocolate's stimulants in our chocolate calculator.

Signs of painkiller poisoning in dogs

With ibuprofen, naproxen and aspirin, the stomach usually shows trouble first: vomiting (sometimes with blood), black tarry stools, diarrhea, belly pain, not eating, weakness and pale gums from blood loss. Kidney damage follows in bigger doses, often first as drinking and peeing more, then making little or no urine. Very large doses affect the brain, with wobbliness, depression, seizures or coma.

Acetaminophen looks different. Dogs may stop eating, vomit, tremble and have belly pain, and some develop a swollen face and paws. At high doses the gums turn brown or muddy and breathing and heart rate speed up, because the blood can no longer carry oxygen well. Don't wait for any of these: by the time signs show, the damage has started.

What to do if your dog ate painkillers

1. Gather the packaging and count what's missing. Assume the highest number it could be.
2. Call your vet, an emergency clinic or a poison hotline: ASPCA Animal Poison Control at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661. Both may charge a fee.
3. Don't give milk, food or anything else unless told to. Vets often make the dog vomit if it was within about 2 hours and the dog has no signs; if they ask you to do it at home, the hydrogen peroxide calculator gives the amount.

Treatment depends on the drug and dose: activated charcoal, stomach protectants for 1 to 2 weeks after NSAIDs, IV fluids for 2 to 3 days to protect the kidneys, and for acetaminophen an antidote called N-acetylcysteine. Not sure what your dog swallowed? Our is it toxic to dogs checker covers other common medicines and household products.