Why it's dangerous
The chemicals are absorbed through inhalation, skin contact, or ingestion, leading to gastrointestinal irritation and systemic toxicity affecting the blood, liver, and kidneys.
Toxic compound: naphthalene, paradichlorobenzene, camphor
How vets treat it
There is no antidote. Because mothballs dissolve slowly, the vet can often still remove them some time after they were eaten. In a cat with no signs, the vet may induce vomiting up to 4 hours after the exposure, then give anti-nausea medicine. A single dose of activated charcoal with a laxative helps soak up what is left in the gut. Vets don't induce vomiting in a cat with nervous-system signs. X-rays or a float test can show whether the mothball was naphthalene or PDB, which matters because naphthalene needs more aggressive treatment. Cats with signs stay in hospital on IV fluids, with blood tests to look for damage to the red blood cells, liver and kidneys. Depending on the signs, treatment can include stomach protectants, medicines for tremors and seizures, vitamin C for methemoglobinemia (a change in the blood that stops it carrying oxygen), blood transfusions for severe anemia, and liver-protecting drugs such as N-acetylcysteine (NAC) and SAMe.
Outlook
There is no antidote, but most cats survive when they get early decontamination and supportive care. The outcome depends on your cat's health, how much it ate and how quickly it is treated. Some cats are left with permanent liver or kidney damage. Death is uncommon but can happen after large doses or when treatment is delayed.
Where pets are exposed
- Mothballs and other moth repellents, such as flakes, crystals, cakes and cubes, used to protect stored clothes and fabric from moths and their larvae.
- Naphthalene mothballs, the older, "old-fashioned" type. Pet Poison Helpline and VCA call them the most toxic type of mothball.
- Paradichlorobenzene (PDB) mothballs. Most modern mothballs contain PDB, which is also used in deodorizers. It is less toxic than naphthalene but can still make a pet ill.
- Camphor mothballs, more common in Asia but also sold in North America. Sources disagree on their risk: Merck rates camphor as the most toxic mothball ingredient, while VCA says camphor mothballs carry a low risk, although large amounts can cause seizures. The camphor guide covers camphor products.
- Loose mothballs put out in the home, yard or garden to keep away snakes, mice or other animals. This use isn't recommended and can harm pets.
- Mothball fumes in closets and storage areas. Mothballs are made to be used in sealed containers, and long-term exposure to the fumes can harm pets and people.
Prevention
- Store mothballs only in closed, airtight containers, out of reach of pets and children.
- Follow the label, and never use loose mothballs in your home, yard or garden to repel pests.
- Don't mix different types of mothballs, or mix mothballs with other chemicals or insecticides.
- Consider non-chemical ways to protect clothes and fabric from insects. Many are safer for pets.
Good to know
Cats are more sensitive to toxic effects, while dogs are more likely to ingest them. Naphthalene is considered more toxic than paradichlorobenzene.
Common questions
My dog ate a mothball, what do I do?
Call your vet or a pet poison line now, even if your dog seems fine. As little as one mothball could poison a dog, and signs can be delayed for several days. Don't make your dog vomit or give anything by mouth unless a vet tells you to. If you can, bring the package and any loose mothballs in a sealed plastic bag so the vet can identify the type.
Are mothball fumes dangerous to cats?
They can be. The chemicals in mothballs can be breathed in as well as swallowed or absorbed through the skin, and long-term exposure to mothball fumes can harm pets and people. Cats are more sensitive to mothballs than dogs. Mothballs are made to be used in sealed containers, so never leave them loose around the home. If your cat seems unwell after being around mothballs, call your vet or a pet poison line.
Which mothballs are the most dangerous to pets?
Naphthalene mothballs, the older type, are considered the most toxic. Most modern mothballs contain paradichlorobenzene (PDB), which is less toxic but can still make a pet ill, and Pet Poison Helpline says both types can be deadly. Sources disagree on camphor mothballs: Merck rates camphor as the most toxic ingredient, while VCA says these carry a low risk. Check the package for the active ingredient and bring it to the vet. Vets can also tell the types apart with X-rays or a float test: a camphor mothball floats in plain water, and in very salty water a naphthalene mothball floats while a PDB mothball sinks. Whatever the type, call your vet or a pet poison line if your pet ate one.
Should I make my pet throw up after eating a mothball?
Not unless a vet tells you to. Call your vet or a pet poison line first. Vets usually start by making the pet vomit, up to 4 hours after the exposure in a pet with no signs, and then give activated charcoal. They don't do it in a pet that trembles or has seizures, so the decision is theirs. Bring the package so the vet knows which type of mothball it was.
Sources
- Merck Veterinary Manual — Toxicosis From Mothballs in Animals
- ASPCA Animal Poison Control Center (Veterinary Medicine, via dvm360) — Toxicology Brief: Moth repellent toxicosis (2005)
- ASPCA Animal Poison Control Center — ASPCA Poison Control
- Pet Poison Helpline — Mothballs
- Pet Poison Helpline — Fall Toxins Poisonous to Dogs & Cats
- VCA Animal Hospitals — Mothball Poisoning in Dogs
- VCA Animal Hospitals — Mothball Poisoning in Cats
- Pet Poison Helpline
This page is informational and is not veterinary advice. If your pet has been exposed to something risky, contact your vet or an animal poison control line right away.
