Mothballs (naphthalene or paradichlorobenzene)

How Much Is Dangerous

A single mothball can cause serious illness in a cat; ingestion of even one is a genuine emergency regardless of which specific chemical formulation is involved, since both naphthalene and paradichlorobenzene carry meaningful risk. The specific chemical formulation (naphthalene versus paradichlorobenzene) does affect exact toxicity and clinical course somewhat, which is part of why bringing product packaging to the veterinary visit genuinely helps guide treatment decisions.

Symptoms

• Vomiting and diarrhea
• Lethargy
• Pale or muddy/brownish-colored gums — a visible sign of developing anemia or methemoglobinemia (a state where hemoglobin can no longer carry oxygen normally)
• Rapid breathing, reflecting the body's attempt to compensate for reduced oxygen-carrying capacity in the blood
• Loss of appetite
• Tremors or, in severe cases, seizures
• Liver damage, evident as jaundice, in significant exposures

Time to Symptoms

Gastrointestinal signs often appear within hours of ingestion; blood-related effects (anemia, methemoglobinemia) and liver effects can take a day or more to become fully apparent, since these reflect a cumulative process of ongoing red blood cell damage rather than an immediate reaction.

First Aid Steps

• Contact a veterinarian or emergency animal hospital promptly for any suspected mothball ingestion, regardless of how the cat appears in the first hour
• Bring the product packaging if available — treatment specifics and expected timeline can differ somewhat depending on the exact chemical (naphthalene versus paradichlorobenzene), so this information is genuinely useful to the treating veterinarian

What Not To Do

• Do not use mothballs in any area a cat can access — store any moth-repellent products in fully sealed containers or spaces genuinely inaccessible to cats, such as sealed storage bins rather than open closet shelves
• Do not assume a "natural" or differently-scented moth-repellent alternative is automatically safer without actually checking its active ingredient — some natural alternatives (like cedar) are genuinely lower-risk, but this should be confirmed rather than assumed from marketing language alone

Veterinary Treatment

Decontamination if caught early after ingestion, followed by monitoring of red blood cell counts and liver values via repeated bloodwork over several days, since the anemia and liver effects develop and evolve over time rather than all at once. Supportive care includes IV fluids and supplemental oxygen if methemoglobinemia is significant enough to impair oxygen delivery. Blood transfusion may be needed in cases of severe anemia.

Toxic Compound

Either naphthalene or paradichlorobenzene depending on the specific product — the two active ingredients used in different mothball formulations, both of which cause oxidative damage to red blood cells, leading to Heinz body formation (clumps of damaged hemoglobin visible on a blood smear) and hemolytic anemia, alongside potential liver and neurological effects. Cats' relatively low activity of the liver enzyme glucuronyl transferase — the same underlying trait behind their well-known unique sensitivity to acetaminophen and many essential oils/phenolic compounds — makes them meaningfully more vulnerable to naphthalene specifically than some other species that clear it more efficiently.