Mothball Poisoning in Dogs and Cats: Symptoms & What to Do

You open an old storage box and immediately recognize the sharp smell of mothballs. Then you notice something more worrying: one appears to be missing, and your dog or cat had access to the area.

This is not a good situation for a “wait and see” approach. Mothballs are concentrated pesticides designed to release insecticidal vapor. Dogs and cats can become poisoned after swallowing them, and substantial inhalation or skin exposure can also cause illness.

Why Are Mothballs Dangerous to Dogs and Cats?

Mothballs are not air fresheners. They are solid pesticides that gradually turn into vapor to kill clothes moths and other fabric pests when used according to their label.

In the United States, mothballs typically contain high concentrations of either naphthalene or paradichlorobenzene (PDB). Camphor-containing moth repellents are also used in some countries and may be encountered in imported products.

The chemicals do not produce exactly the same toxic effects, which makes the original package valuable. If you’re unsure where to find the active ingredient or safety directions, see our guide to reading pesticide labels when you have pets.

The Closet Count

Mothball emergencies often begin with uncertainty. You find an open closet, damaged package, or old storage chest but did not actually see your pet swallow anything.

Save the package or take clear photographs of the front and back label. The active ingredient and product form can affect the expected signs and treatment plan.

Naphthalene vs. PDB vs. Camphor

The major concern is not deciding which ingredient is “safe enough.” All require veterinary attention after a meaningful ingestion. Their typical toxic effects simply differ.

Naphthalene is particularly important because it can cause oxidative damage to red blood cells. Severe cases may develop hemolytic anemia or methemoglobinemia, interfering with normal oxygen delivery and producing weakness, breathing difficulty, or unusually pale or brownish gums.

PDB more commonly produces gastrointestinal and neurological effects, while important camphor exposure can affect the central nervous system. The actual risk still depends on dose, product size, species, body weight, and route of exposure.

How Are Pets Exposed?

Ingestion is the most common exposure, especially in dogs. A loose mothball is small enough to pick up, chew, or swallow.

Veterinary toxicology references also recognize inhalation and skin absorption as possible exposure routes. Cats are suspected to be more sensitive to mothball toxicity than some other species, while dogs are more likely to actually ingest the product.

The practical rule is the same for both: mothballs should remain completely inaccessible.

Can Mothball Fumes Harm Pets?

Yes. Mothballs slowly change from a solid into pesticide vapor. In the United States, their labels typically direct users to place them in tightly closed storage containers so the vapor remains concentrated around the stored fabric rather than escaping into occupied living space.

If you can strongly smell mothballs in a room, pesticide vapor is present in the air. Mothballs should not be scattered through closets, rooms, attics, garages, yards, gardens, or other areas as general-purpose animal repellents unless a specific pesticide label authorizes that use.

Prolonged or substantial vapor exposure can cause illness. If mothballs were left loose in a living area, keep pets away, collect and secure the pesticide according to the label, ventilate the area, and follow the product’s disposal instructions. If your pet develops vomiting, marked lethargy, respiratory changes, eye irritation, neurological signs, or another abnormal change, contact a veterinarian.

Symptoms of Mothball Poisoning

Signs vary by ingredient and dose, and they may not begin immediately. Mothballs dissolve slowly in the gastrointestinal tract, so a pet can initially appear normal after an ingestion and still develop toxicity later.

Possible signs include:

• Vomiting or diarrhea
• Abdominal discomfort
• Loss of appetite
• Mothball-like odor on the breath or vomit
• Lethargy or weakness
• Pale, brownish, or otherwise abnormal-looking gums
• Rapid or difficult breathing
• Dark or abnormal urine
• Unsteady walking or poor coordination
• Trembling or tremors
• Seizures

What to Do If Your Dog or Cat Eats a Mothball

1. Stop further exposure. Move your pet away from the product and prevent access to any remaining mothballs.
2. Count what remains. Estimate how many may be missing.
3. Identify the product. Find the active ingredient, product name, and package size if possible.
4. Call immediately. Contact your veterinarian, an emergency veterinary clinic, or a veterinary poison-control service.
5. Give useful details. Provide your pet’s species, approximate weight, possible amount swallowed, time of exposure, and any current symptoms.
6. Do not induce vomiting yourself. Whether veterinary decontamination is appropriate depends on timing, clinical condition, species, ingredient, and aspiration risk.
7. Do not give home remedies. Avoid hydrogen peroxide, salt, milk, oil, food, activated charcoal, or another treatment unless a veterinary professional specifically instructs you to use it.
8. Bring the package. Take the original container or clear photographs of the label to the clinic.

Do not assume several hours passing means treatment is pointless. Mothballs dissolve slowly, and Merck notes that professionally supervised gastrointestinal decontamination can sometimes remain useful later than it would for many rapidly absorbed toxins.

How Is Mothball Poisoning Treated?

There is no single treatment protocol for every mothball exposure. Veterinary care depends on the active ingredient, amount, time since ingestion, symptoms, and laboratory findings.

Depending on the case, treatment may include professionally supervised gastrointestinal decontamination, anti-nausea medication, blood testing, intravenous fluids, medications for tremors or seizures, oxygen or respiratory support, and monitoring of red-blood-cell, liver, and kidney function.

Serious blood abnormalities caused by naphthalene may require intensive supportive treatment, including transfusion in some cases.

Are Cats More Sensitive Than Dogs?

Veterinary toxicology references state that cats are suspected to be more sensitive to mothball toxicity than some other species. Dogs, however, are more likely to pick up and swallow mothballs.

That distinction should not change what you do after a suspected ingestion. For either species, identify the product and contact veterinary help promptly rather than trying to estimate safety from body size alone.

How to Prevent Mothball Poisoning

Mothballs become especially risky when they are treated like ordinary deodorizer balls or general-purpose pest repellents. They are pesticides and should only be used as the product label directs.

Keep unused mothballs in their original labeled packaging and inaccessible to pets. When the label calls for an airtight storage container, use one that closes securely and cannot be opened by your dog or cat.

Check older storage spaces too. Seasonal clothing boxes, inherited furniture, garages, basements, trunks, and forgotten closets may contain mothballs placed there years earlier.

Do You Need Mothballs at All?

Often, clothes-moth problems can be managed without immediately reaching for a pesticide. Start by identifying the pest and finding the infested materials.

• Clean clothing before long-term storage.
• Store clean susceptible fabrics in tightly sealed containers.
• Vacuum closets, shelving, carpet edges, cracks, and undisturbed areas.
• Inspect wool, fur, feathers, natural-fiber rugs, and other susceptible materials.
• Launder, dry-clean, freeze, or otherwise treat infested materials using an appropriate method for the item.
• Monitor for continuing moth activity before adding pesticide treatment.

If you do choose a pesticide, use only a product labeled for the actual pest and location. For broader lower-exposure pest-control strategies, see our pet-safe pest-control guide for dog homes or our pet-safe pest-control guide for cat homes.

The Bottom Line

Mothballs are easy to underestimate because they are small, familiar, and associated with closets rather than pesticide bottles. But they contain concentrated insecticidal chemicals, and swallowing even one can be dangerous.

If a mothball is missing and your dog or cat had access, do not wait for vomiting, tremors, unusual gum color, weakness, or breathing problems. Count what remains, save the package, identify the active ingredient, and contact veterinary help promptly.

Treat a missing mothball like a possible pesticide ingestion—not a missing air freshener.