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. Vets commonly induce vomiting, give repeated doses of activated charcoal (naproxen cycles back through the gut), prescribe stomach protectants for 1 to 2 weeks, and give IV fluids for about 3 days when kidney injury is possible.
Go straight to an emergency vet if…
- Your dog is vomiting (especially blood), has black or tarry stool, is weak, wobbly, or having a seizure
- The estimated dose is in the Emergency range
- Your dog is older, has known kidney, liver, or stomach problems, or also takes another NSAID or a steroid
- A poison control consultation or your vet has told you to bring the dog in
Call poison control first if…
- Your dog just ate the pills and seems normal (signs often start 2 to 24 hours later)
- You are unsure of the tablet strength or how many were eaten
- The product was a combination medicine (Aleve PM, Aleve-D, Midol) with other ingredients
- You want a case number and treatment plan to hand to your vet
How naproxen poisoning develops
Naproxen blocks the prostaglandins that protect the stomach lining and keep blood flowing to the kidneys. In dogs it is cleared mainly through the bile and recirculates through the gut, which is why its effects last so long.
Stomach and gut signs
- Vomiting, sometimes with blood
- Diarrhea or black, tarry stool
- Belly pain, loss of appetite, lethargy
Kidney injury (higher doses)
- Increased or decreased thirst and urination
- Weakness, poor appetite, bad breath
- Kidney values on bloodwork may rise before signs appear
Ulcer complications
- Pale gums from blood loss
- Severe belly pain or collapse
- A perforated ulcer is life-threatening
Published case data behind these estimates
These figures come from the Merck Veterinary Manual and ASPCA Animal Poison Control Center (APCC) data published in veterinary journals. They describe documented clinical effects, not a line between "safe" and "dangerous." The two APCC sources give slightly different cutoffs, so this calculator uses the lower (more cautious) number from each.
| Single naproxen dose | Documented clinical effect |
|---|---|
| 1 – 7 mg/kg | Vomiting and lethargy reported in APCC cases (DeClementi, 2013) |
| ≥ 5 mg/kg | Can cause stomach and gut ulceration in young, healthy dogs (APCC data, DeClementi, 2012). A later APCC review puts this at 7 mg/kg. |
| ≥ 10 mg/kg | Kidney injury possible at 10 to 20 mg/kg or higher (APCC data, 2012). Rising kidney values were seen at 13 to 15 mg/kg (APCC data, 2013). |
| 35 mg/kg | A single dose caused vomiting blood, black stool, diarrhea, and belly pain (Merck Veterinary Manual) |
| 5.6 mg/kg daily | Given for 7 days, caused vomiting, black stool, pale gums, and weakness (Merck Veterinary Manual) |
This calculator uses: under 5 mg/kg = contact a professional now; 5 to under 10 mg/kg = Urgent; 10 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 5 mg/kg or more is shown as Emergency, because these dogs are at higher risk of kidney injury. The calculator uses the mg number on the label; Aleve's 220 mg of naproxen sodium is about 200 mg of naproxen, so the estimate leans slightly high on purpose.