Is Naphthalene Toxic to Dogs? Mothball Poisoning Signs

Name: Is Naphthalene Toxic to Dogs? Mothball Poisoning Signs
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Is naphthalene toxic to dogs? Yes. Naphthalene is the active ingredient in many traditional mothballs sold in the United States, and it is poisonous to dogs even in small amounts. A dog that eats a mothball can develop vomiting, pale gums, tremors, and seizures, sometimes within hours.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Naphthalene mothballs are toxic to dogs. Ingestion is the most common exposure, but inhaling fumes or absorbing the chemical through the skin can also cause poisoning [1].
The first signs are usually stomach upset (vomiting, loss of appetite, belly pain) and lethargy, which can progress to hemolytic anemia, methemoglobinemia, trouble breathing, pale gums, and in rare cases tremors and seizures [1].
Do not induce vomiting unless a veterinarian tells you to. Call your vet, the ASPCA Animal Poison Control Center at (888) 426-4435, or Pet Poison Helpline at (855) 764-7661 first.
Go to an emergency clinic right away if your dog ate a mothball, is vomiting, has pale gums, is wobbling, or is having a seizure.
Bring the package or a photo of the product if you can. Knowing whether it is naphthalene or paradichlorobenzene changes the treatment plan [1].

Is Naphthalene Toxic to Dogs?

Yes. Naphthalene is one of the main moth repellent ingredients used in the United States, along with paradichlorobenzene (often called PDB) [1]. Both are toxic to dogs. Camphor, a third type of mothball ingredient used more often in other countries, is considered the most toxic of the three, followed by naphthalene, then PDB [1].

All animals can be affected by mothball exposure, and cats are suspected to be more sensitive than other species [1]. That does not make dogs safe. A dog's smaller body size compared with a person means a single mothball can deliver a much larger dose relative to body weight.

Which Products Contain Naphthalene?

Naphthalene shows up in traditional mothballs and moth flakes, in some urinal cakes and deodorizer blocks, and in certain pest repellents. It is also a common indoor air pollutant, and very high indoor concentrations are sometimes found when the chemical is used as a pest repellent or deodorant [2]. That matters for dogs kept in closets, basements, garages, or storage rooms where mothballs are sitting out.

Naphthalene is also part of the polycyclic aromatic hydrocarbon (PAH) family. A study of commercial dry dog food and matching urine samples found naphthalene was the predominant PAH in both, making up about 73 percent of total PAHs in food and its metabolites about 79 percent of total metabolites in urine [3]. That is background dietary exposure at very low levels, not the same as eating a mothball. It does mean tiny amounts of naphthalene are common in the environment, so the dose and the source matter.

Are Mothballs Toxic to Dogs in General?

Any mothball is a problem, no matter which active ingredient it contains. Exposure to any type of mothball product can cause gastrointestinal signs such as vomiting, loss of appetite, and abdominal discomfort, plus lethargy [1]. Ingestion is the most common route, but inhalation and absorption through the skin can also cause toxicosis [1].

If you are not sure what your dog got into, treat it as an emergency anyway. The product label is the fastest way to identify the ingredient, and your veterinarian can use that information to guide treatment.

What Naphthalene Does in the Body

Naphthalene is a gastrointestinal irritant. That is why exposure almost always causes GI signs such as vomiting and anorexia before any systemic signs appear [1]. If your dog vomits shortly after getting into a mothball, that is not a sign the danger has passed. It is often the first stage.

Once absorbed, naphthalene and its breakdown products can damage red blood cells. With large exposures, this leads to hemolytic anemia (red blood cells destroyed faster than the body can replace them), methemoglobinemia (a form of hemoglobin that cannot carry oxygen well), difficulty breathing, and pale gums [1]. These are the changes that make naphthalene poisoning dangerous instead of just uncomfortable.

The nervous system can also be affected. Trembling, tremors, ataxia (wobbliness), and seizures are reported in rare cases [1]. Seizures are not the typical first sign, but they can happen, and they signal a serious exposure.

Research in insects exposed to naphthalene vapor shows changes in genes tied to oxidative stress, metabolism, reproduction, and neurotransmission [4]. That work was done in insects, not dogs, so it cannot be translated into dog doses or timelines. It does support the general picture that naphthalene disrupts multiple body systems, including nerve signaling.

Naphthalene Poisoning Signs in Dogs and the Timeline

Signs usually start with the gut, then move to the blood and nervous system. The timeline depends on how much was eaten, how big your dog is, and whether the mothball was chewed or swallowed whole.

Early Signs (Often Within Hours)

Vomiting
Loss of appetite
Abdominal pain or discomfort
Lethargy or unusual tiredness

These GI and energy changes are the most common early findings after mothball exposure [1].

Later or More Serious Signs

Pale gums
Labored or rapid breathing
Weakness or collapse
Dark or brownish gums (a possible sign of methemoglobinemia)
Trembling, tremors, or unsteady walking
Seizures

Hemolytic anemia, methemoglobinemia, dyspnea, and pale gums occur with large exposures, and neurologic signs such as trembling, tremors, ataxia, and seizures are noted in rare cases [1].

How Fast Does It Happen?

Veterinary references do not give a single fixed number of hours for dogs, and the exact timing is not well established in veterinary research. What is clear is that GI signs tend to come first and systemic signs follow with larger exposures [1]. Treat any suspected mothball ingestion as time-sensitive and do not wait to see what happens.

Dog Ate Mothballs: What to Do Right Now

Move your dog away from the source. Pick up any remaining mothballs, flakes, or packaging so your dog cannot eat more.
Do not induce vomiting unless a veterinarian tells you to. Naphthalene is a GI irritant, and forcing vomiting can cause harm or make things worse if your dog is already weak, wobbly, or having neurologic signs.
Call for guidance right away. Reach your own veterinarian, the ASPCA Animal Poison Control Center at (888) 426-4435, or Pet Poison Helpline at (855) 764-7661.
Save the evidence. Keep the package, the label, or a clear photo of the product. Your vet needs to know whether it is naphthalene, PDB, or camphor [1].
Go to the emergency clinic if your dog is vomiting, has pale gums, is breathing hard, is wobbling, or has had a seizure. Do not drive around looking for answers first.

If your dog got into something else while you were cleaning, the same rule applies. For example, if you are also worried about a dog that ate a mushroom or a dog that ate a toad, call poison control or your vet before trying any home remedy.

How Veterinarians Treat Mothball Poisoning in Dogs

Treatment after exposure is aimed at decontamination and supportive care [1]. Your veterinarian will decide what that means for your dog based on the exam, the amount eaten, and how sick the dog is.

Decontamination may include inducing vomiting in a controlled setting, giving activated charcoal, or washing the skin if the mothball was held in the mouth or rubbed against the coat. Your vet may also use imaging. Radiography can help tell naphthalene mothballs apart from PDB mothballs, because PDB mothballs are densely radiopaque while naphthalene mothballs are radiolucent or only faintly radiopaque [1]. That difference can guide how the case is managed.

Supportive care can include intravenous fluids, medications to control vomiting, oxygen if breathing is affected, and treatment for anemia or methemoglobinemia if those develop. Seizures are managed with anticonvulsant medication. Any drug dose is calculated by your veterinarian from your dog's weight and health status, so there is no safe home dose to give on your own.

Outlook After Naphthalene Exposure

The outlook depends on how much naphthalene your dog absorbed, how quickly treatment started, and whether blood or neurologic problems developed. Dogs with only mild GI signs often do well with prompt decontamination and supportive care. Dogs that develop hemolytic anemia, methemoglobinemia, breathing difficulty, or seizures need more intensive treatment and have a more guarded prognosis.

Veterinary references describe these severe outcomes as occurring with large exposures, and seizures as rare [1]. That is reassuring for small, caught-early ingestions, but it is not a reason to watch and wait at home. Early treatment is the main thing you can control.

Preventing Mothball Poisoning and Safer Alternatives

The simplest prevention is to stop using naphthalene mothballs in any space your dog can reach. That includes closets, basements, garages, laundry rooms, storage bins, and anywhere a mothball could roll under furniture.

Store mothballs in sealed, dog-proof containers, ideally in a room your dog never enters.
Check pockets, coat linings, and stored blankets before bringing them into living areas.
Watch for dropped or scattered mothballs after cleaning or reorganizing.
Keep dogs out of crawl spaces and attics where repellents are placed.
If you use a pest repellent or deodorizer indoors, remember that naphthalene can build up in indoor air, and very high concentrations have been measured indoors when the chemical is used this way [2].

For clothing and textile storage, physical barriers work well. Airtight bins, cedar blocks, lavender sachets, and regular washing or dry cleaning keep moths away without leaving a toxic pellet where a dog can find it. If you must use a chemical repellent, use it only in a sealed container in a space your dog cannot access.

If your dog has a habit of eating things that are not food, talk with your veterinarian about it at your next visit. That pattern raises the odds of a repeat event with mothballs, medications, or household toxins. For example, a dog that ate a peach pit faces a different set of risks, but the underlying behavior is the same one that leads to mothball ingestion. If your dog also takes allergy medication, double-check what is safe before you reach for a human product, since not every antihistamine is appropriate for dogs, as covered in this guide to dog antihistamines for allergies.

Limitations and When to Contact a Veterinarian

This article covers general information. Your dog's case needs a veterinarian who can examine your dog, ask about the product, and decide on treatment.

Contact a veterinarian the same day if your dog may have eaten a mothball or licked one, even if your dog seems fine right now. GI signs often come first, and problems can develop after a quiet period [1].

Go to an emergency clinic now if you see any of these:

Vomiting that will not stop
Pale, white, or bluish gums
Fast, labored, or noisy breathing
Weakness, collapse, or inability to stand
Trembling, tremors, unsteady walking, or a seizure
Known or suspected ingestion of more than a tiny amount, or any ingestion in a small dog or puppy

Schedule a routine visit if your dog has a history of eating non-food items, if you use mothballs anywhere in the home, or if you want help choosing safer pest control options.

Frequently Asked Questions

How much naphthalene is dangerous for a dog?

There is no single published threshold that applies to every dog, and the amount that causes serious illness depends on body weight and individual sensitivity. Veterinary references describe severe effects such as hemolytic anemia and seizures as occurring with large exposures [1]. If your dog ate any amount of a naphthalene product, call poison control or your veterinarian for a case-specific assessment.

Can a dog get sick just from smelling mothballs?

Yes, inhalation is one of the routes that can cause toxicosis, along with ingestion and absorption through the skin [1]. Dogs kept in small, poorly ventilated spaces with mothballs can be exposed to fumes over time. If you notice vomiting, appetite loss, or lethargy in a dog that lives or sleeps near mothballs, move the dog to fresh air and call your veterinarian.

How long do naphthalene poisoning signs take to appear in dogs?

Veterinary sources do not give a fixed number of hours for dogs, and the timing is not well established in veterinary research. GI signs such as vomiting and anorexia tend to appear before systemic signs, and blood or neurologic problems follow larger exposures [1]. Because of that pattern, a dog that looks normal an hour after eating a mothball still needs veterinary guidance.

Should I make my dog vomit after eating a mothball?

No, not unless a veterinarian tells you to. Naphthalene irritates the stomach and gut, and vomiting can be risky if your dog is already weak, wobbly, or showing neurologic signs [1]. Call your vet, the ASPCA Animal Poison Control Center at (888) 426-4435, or Pet Poison Helpline at (855) 764-7661 and follow their instructions.

Are paradichlorobenzene mothballs safer than naphthalene ones?

Naphthalene is considered more toxic than paradichlorobenzene, and camphor is considered the most toxic of the three [1]. That ranking does not make PDB mothballs safe. Any mothball exposure can cause vomiting, appetite loss, abdominal discomfort, and lethargy, and all of them warrant a call to your veterinarian [1].

References

Toxicosis From Mothballs in Animals - Toxicology. Merck Veterinary Manual.
Sources, concentrations, and risks of naphthalene in indoor and outdoor air. Indoor air, 2012.
Dietary exposure to polycyclic aromatic hydrocarbons in pets: Evidence from urinary biomonitoring. Environmental research, 2025.
Toxicity of Naphthalene and Benzene on Tribollium castaneum Herbst. International journal of environmental research and public health, 2017.