CatToxic

Naproxen (Aleve)

Dangerous

Verdict

Never — a long-acting NSAID with the same gut and kidney risks as ibuprofen.

Toxic principle: long-acting NSAID
Also called: aleve, naprosyn
Source: Merck Veterinary Manual · Verified 2026-08-13

If your cat ate this

Cats hide symptoms — don't wait and see. Even small amounts of certain substances can be fatal to a cat. Act fast.

  1. 1. Call your veterinarian immediately
  2. US — National hotline: ASPCA Animal Poison Control Center (888) 426-4435 aspca.org(24/7, Consultation fee may apply.)
  3. US — National hotline: Pet Poison Helpline (855) 764-7661 petpoisonhelpline.com(24/7, $89 per incident fee; also covers Canada.)
  4. GB — National hotline: Animal PoisonLine 01202 509 000 animalpoisonline.co.uk(24/7, £35 per call (8am–8pm weekdays), £45 at other times.)
  5. AU — National hotline: Animal Poisons Helpline 1300 869 738 animalpoisons.com.au(24/7)
  6. NZ — National hotline: Animal Poisons Helpline 0800 869 738 poisons.co.nz(11am–7pm NZ time (currently being extended), Charges apply.)
  7. CA — National hotline: Pet Poison Helpline (855) 764-7661 petpoisonhelpline.com(24/7, $89 per incident fee.)

Verified 2026-08-06

Verdict

Naproxen lasts longer than ibuprofen, which is convenient for people and worse for a small cat. Expect the same ulcer and kidney story. One caplet is an overdose.

Symptoms to watch for

  • • vomiting
  • • lethargy
  • • black stool
  • • decreased urination

What to do

Emergency. Bring the package. Do not give another NSAID “to help.”

ASPCA Animal Poison Control Center: (888) 426-4435 aspca.org

Related foods

Ibuprofen

Dangerous

Never — NSAIDs ulcerate the gut and injure feline kidneys.

Pain relievers

Aspirin

Dangerous

Never give leftover aspirin. It is an NSAID and cats clear salicylates slowly.

Pain relievers

Acetaminophen (Tylenol)

Dangerous

Never — a single regular-strength tablet can kill a cat.

Pain relievers

5-fluorouracil cream

Dangerous

Never — tiny amounts of 5-FU cream are often fatal to cats.

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