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🚨 Emergency — Toxic
Naproxen is very toxic to dogs. Naproxen is very toxic to cats.
Naproxen, sold under the brand name Aleve among others, is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain, menstrual cramps, and inflammatory diseases such as rheumatoid arthritis, gout and fever. It is taken orally. Read more on Wikipedia →
More dangerous than ibuprofen for dogs due to longer duration of action. Causes severe stomach ulcers and kidney failure. Even a single pill can be life-threatening.
Naproxen is a methoxynaphthalene that is 2-methoxynaphthalene substituted by a carboxy ethyl group at position 6. Naproxen is a non-steroidal anti-inflammatory drug commonly used for the reduction of pain, fever, inflammation and stiffness caused by conditions such as osteoarthritis, kidney stones, rheumatoid arthritis, psoriatic arthritis, gout, ankylosing spondylitis, menstrual cramps, tendinitis, bursitis, and for the treatment of primary dysmenorrhea. It works by inhibiting both the COX-1 and COX-2 enzymes. It has a role as a non-steroidal anti-inflammatory drug, a non-narcotic analgesic, an antipyretic, a xenobiotic, a gout suppressant, a cyclooxygenase 2 inhibitor, a cyclooxygenase 1 inhibitor, an environmental contaminant and a drug allergen. It is a monocarboxylic acid and a methoxynaphthalene. It is a conjugate acid of a naproxen(1-). PubChem reference
Symptoms can appear anywhere from 30 minutes to 12 hours after ingestion depending on the substance and the amount. Even if your dog seems fine, call your vet — outcomes are dramatically better with early treatment.
NSAIDs like naproxen are extremely dangerous for cats, causing kidney failure and GI ulceration. Even a small amount can be fatal. Seek emergency vet care.
Cats are even more sensitive than dogs to many household substances because they have a reduced ability to metabolise certain compounds (limited glucuronidation). Any suspected ingestion should be treated as an emergency — call your veterinarian immediately, even if your cat appears fine.
Even with safe foods, individual sensitivities are real. Stop feeding and call your vet if you see any of:
If your pet's symptoms are severe, contact an emergency veterinarian immediately. In the United States the ASPCA Animal Poison Control Center is reachable 24/7 at +1 (888) 426-4435.
Any amount of naproxen should be treated as a potential emergency. Toxic dose varies with body weight, age, and individual sensitivity. Call your vet immediately with the dog's weight and the estimated amount ingested.
Common early signs are vomiting, diarrhea, drooling, restlessness, and weakness. Severe cases progress to tremors, seizures, irregular heart rate, and collapse, typically within a few hours.
Yes. Some toxins cause delayed symptoms (hours to a full day later), and once signs appear the case is already serious. Early treatment dramatically improves the outcome.
Cats are usually more sensitive to toxins than dogs. Any suspected ingestion should be treated as an emergency.
Anywhere from 24 hours to several days, depending on the substance and how quickly treatment was started. Hospitalised pets often receive IV fluids and supportive care for the full duration.
Store all known toxic substances in closed cupboards above counter height, brief everyone in the household, and save the ASPCA Poison Control number (+1 888 426 4435) in your phone.