- Even one can be toxic
- Within hours
- Affects: Liver & red blood cells
Why this verdict for cats
Cats are especially sensitive to naphthalene mothballs, which can cause organ and red-blood-cell damage. Treat any ingestion as an emergency.
Warning signs to watch for
- Vomiting
- Lethargy
- Pale gums
⚠ If your cat ate mothballs
Act immediately — don't wait for symptoms.
- Call your vet or a pet poison helpline right away.
- Note how much was eaten and when.
- Do not induce vomiting unless a professional tells you to.
Mothballs are an old-fashioned product that causes thoroughly modern poisonings, and there is one detail that changes everything: they are made from two different chemicals, and one is several times more dangerous than the other.
How much is safe?
Naphthalene mothballs are the serious ones, and a single ball can poison a small dog. Paradichlorobenzene mothballs are roughly half as toxic and usually cause milder illness at the same dose. Older products and those with a strong classic mothball smell are more likely to be naphthalene. A rough field test: a mothball that sinks in plain water and floats in salty water is more likely to be naphthalene, but do not delay a phone call to run experiments. The vapours alone can also irritate pets in an enclosed space.
What happens if a cat eats too much?
Vomiting, often within a couple of hours, along with lethargy and sometimes tremors or seizures. Naphthalene then destroys red blood cells, producing pale or yellow-tinged gums, weakness, fast breathing and brown or red urine over the following day or two, plus possible liver damage. Cats are more susceptible to this red-cell damage than dogs.
⚠ What to do if your cat ate mothballs
Call your vet or a poison line immediately and take the packaging if you have it (ASPCA 888-426-4435 · Pet Poison Helpline 855-764-7661). Do not induce vomiting at home. Treatment depends on which chemical is involved and typically includes decontamination, fluids, liver support and monitoring red blood cell counts for several days. If you use mothballs, a sealed garment bag your pet cannot reach is the only safe storage.
⚠️ Worried your pet got into this?
Frequently asked questions
My dog just licked one and spat it out — is that enough?
Possibly, especially for a small dog and especially if it is naphthalene. Call and describe what happened.
Are the smell alone and the vapours harmful?
Prolonged exposure in a closed room or wardrobe can irritate the airways and, over time, contribute to red-cell damage. Ventilate and remove the source.
More household items for cats
By the CanMyPet Editorial Team · Reviewed against ASPCA Animal Poison Control, the American Kennel Club (AKC) and Pet Poison Helpline · Last updated July 31, 2026.
Sources
- ASPCA — People Foods to Avoid Feeding Your Pets
- American Kennel Club — Dog Nutrition
- Pet Poison Helpline — Poison List