Mothballs are genuinely dangerous household products that contain pesticide-grade chemicals in nearly pure concentrations. The two active ingredients found in commercial mothballs, naphthalene and paradichlorobenzene, are both registered pesticides capable of harming people, pets, and wildlife through ingestion, skin contact, or simply breathing the vapors. Despite their familiar, old-fashioned reputation, mothballs cause real poisoning cases every year, and the risks extend well beyond the occasional swallowed ball.
What Mothballs Actually Contain
A mothball is not a mild household product with a trace of something unpleasant. It is a solid block of nearly pure chemical that slowly turns into gas at room temperature, a process called sublimation. The two chemicals used in mothballs are naphthalene and paradichlorobenzene (sometimes written as p-DCB or 1,4-dichlorobenzene). Both are found at nearly pure concentrations in moth repellents and deodorizers used in closets, garment bags, and sometimes toilet bowls.1PubMed. Emissions of p-dichlorobenzene and naphthalene from consumer products A third ingredient, camphor, shows up in some products but is far less common in the United States and Europe.
Naphthalene is the older of the two chemicals and the one more commonly associated with serious poisoning. It has a distinctive, sharp, tarry smell that most people recognize as “the mothball smell.” Paradichlorobenzene largely replaced naphthalene in many consumer products because it was considered somewhat less acutely toxic, but “less toxic” does not mean safe. Both chemicals are hazardous, and both are legally classified as pesticides, meaning their label directions carry the force of law.2EDIS. The Facts about Mothballs
How Mothballs Harm the Body
The damage from mothball exposure depends on which chemical is involved, how much exposure occurred, and whether it was swallowed, inhaled, or absorbed through the skin. Both naphthalene and paradichlorobenzene cause severe oxidative stress inside the body, which means they generate reactive molecules that attack red blood cells and other tissues. The two most characteristic injuries are hemolysis, where red blood cells are destroyed faster than the body can replace them, and methemoglobinemia, where hemoglobin is chemically altered so it can no longer carry oxygen properly.3PubMed Central. Severe Hemolytic Anemia After Mothball Ingestion Complicated by an Undiagnosed Enzyme Deficiency: A Case Report The result is that the blood loses its ability to deliver oxygen to organs, even though the person is still breathing normally.
Paradichlorobenzene adds another layer of risk beyond blood damage. Chronic or heavy exposure to p-DCB can affect multiple organ systems, including the liver, kidneys, skin, lungs, and the central nervous system. Neurological damage from p-DCB is a particular concern, as it can cause leukoencephalopathy, a condition where the white matter of the brain deteriorates, leading to a range of symptoms from tremors and confusion to difficulty walking.4PubMed Central. Para-dichlorobenzene toxicity – a review of potential neurotoxic manifestations Occupational studies of workers exposed to p-DCB have found elevated white blood cell counts, signs of liver stress, and markers suggesting kidney strain compared to unexposed workers.5PubMed. Effects of occupational exposure to 1,4-dichlorobenzene on hematologic, kidney, and liver functions
Children and Mothball Poisoning
Accidental ingestion by young children is one of the most common and dangerous mothball exposure scenarios. Mothballs are small, round, and sometimes white or translucent, which makes them easy for a toddler to mistake for candy or a toy. A single mothball contains enough chemical to cause serious harm in a small body. Published case reports paint a grim picture of what happens when a child swallows one.
In one case, a three-year-old boy who had swallowed naphthalene mothballs developed severe hemolytic anemia and methemoglobinemia within days of ingestion and required treatment with ascorbic acid and N-acetylcysteine.6The Journal of Emergency Medicine. Naphthalene Toxicity in a Three-Year-Old Child Complicated by Severe Hemolytic Anemia and Mild Methemoglobinemia: A Case Report Another case involved a 13-month-old who developed hemolysis, lactic acidosis, methemoglobinemia, acute kidney failure, liver dysfunction, and rhabdomyolysis (breakdown of muscle tissue) all at once after mothball ingestion. That child required aggressive fluid treatment, multiple blood transfusions, and mechanical ventilation.7PubMed Central. Mothball Ingestion in the Setting of G6PD Deficiency Causing Severe Hemolytic Anemia, Methemoglobinemia, and Multiple Organ Failure in a Toddler Yet another report described massive intravascular hemolysis and acute kidney injury following naphthalene ball consumption.8PubMed Central. Naphthalene ball poisoning: a rare cause of acquired methaemoglobinaemia
The common thread in pediatric poisoning cases is that symptoms often do not appear immediately. A child might swallow a mothball and seem fine for a day or two before the oxidative damage becomes severe enough to produce visible signs like dark urine, pale skin, rapid breathing, or lethargy. By the time parents seek medical attention, the damage to red blood cells and organs can already be extensive. If you suspect a child has swallowed or even chewed on a mothball, treat it as a medical emergency regardless of how the child appears.
The G6PD Factor
One genetic condition dramatically amplifies the danger of mothball exposure. Glucose-6-phosphate dehydrogenase deficiency, commonly known as G6PD deficiency, is an inherited enzyme shortage that affects roughly 400 million people worldwide. It is particularly common in people of African, Mediterranean, Middle Eastern, and Southeast Asian descent. People with G6PD deficiency have red blood cells that are far more vulnerable to oxidative stress because they cannot produce enough of a protective molecule that normally shields cells from damage.
When someone with G6PD deficiency is exposed to naphthalene or paradichlorobenzene, the hemolytic reaction is more severe and harder to reverse. The oxidizing chemicals in mothballs overwhelm the already limited defenses of their red blood cells, leading to rapid and massive destruction of those cells.3PubMed Central. Severe Hemolytic Anemia After Mothball Ingestion Complicated by an Undiagnosed Enzyme Deficiency: A Case Report The 13-month-old who developed multi-organ failure from mothball ingestion, described above, had previously undiagnosed G6PD deficiency, which almost certainly worsened the outcome.7PubMed Central. Mothball Ingestion in the Setting of G6PD Deficiency Causing Severe Hemolytic Anemia, Methemoglobinemia, and Multiple Organ Failure in a Toddler
Many people carry G6PD deficiency without knowing it, since the condition usually causes no symptoms until something triggers a hemolytic episode. Mothball exposure is one of those triggers. If you have a family history of G6PD deficiency, or if you belong to a population where the condition is prevalent, it is worth keeping mothballs out of your home entirely. Even vapor exposure from stored mothballs can theoretically trigger hemolysis in highly sensitive individuals, though ingestion is the most documented route of serious harm.
The Indoor Air Problem
You do not have to eat a mothball to be harmed by one. Because both naphthalene and paradichlorobenzene sublimate at room temperature, they continuously release vapor into the surrounding air. In an enclosed space like a closet, storage bin, or poorly ventilated room, the concentration of those vapors can build up substantially. Research has confirmed that mothball use is a significant contributor to indoor naphthalene concentrations.9PubMed Central. Naphthalene Mothballs: Emerging and Recurring Issues and their Relevance to Environmental Health
Studies measuring emission rates from mothball products have found that they release naphthalene at rates between roughly 840 and 1,015 micrograms per gram of mothball per hour.10Atmospheric Environment. Household materials as emission sources of naphthalene in Canadian homes and their contribution to indoor air That rate is high enough that even a few mothballs tucked into a bedroom closet can measurably elevate the naphthalene level throughout the room. The vapors do not stay contained, they permeate fabrics, seep through gaps in closed containers, and linger long after the mothballs themselves are removed. People living in homes where mothballs are used heavily sometimes carry detectable levels of naphthalene metabolites in their urine without realizing they have been chronically exposed.
Chronic low-level inhalation is harder to study than acute poisoning, but the concern is real. Naphthalene has been classified as a possible human carcinogen by several international health agencies based on evidence of nasal tumors in laboratory animals. Even short of cancer, ongoing inhalation can irritate the eyes, nose, throat, and lungs. Some people who habitually use large quantities of mothballs in their homes report headaches, nausea, and fatigue that resolve after the mothballs are removed. If you can smell mothballs anywhere in your house, you are inhaling the chemical, and the stronger the smell, the higher the concentration.
How to Tell Which Chemical You Have
Knowing whether a mothball contains naphthalene or paradichlorobenzene matters for treatment decisions if someone is exposed. The two chemicals have different toxicity profiles and different treatment protocols. Unfortunately, the packaging is not always available or legible when a poisoning occurs. Emergency physicians have developed a few quick tests to distinguish between them.
The simplest initial clue is smell. Naphthalene has a strong, distinctive, tarry odor, while paradichlorobenzene tends to have a somewhat sweeter, more “chemical” smell. This distinction is subjective, though, and not reliable enough on its own.11Annals of Emergency Medicine. Mothball composition: Three simple tests for distinguishing paradichlorobenzene from Naphthalene
A more definitive approach involves placing the mothball in liquid. If you drop a mothball into plain water, camphor floats while both naphthalene and paradichlorobenzene sink. To distinguish between the two sinkers, placing them in a concentrated sugar solution (clinically, a 50-percent dextrose solution) reveals the difference: naphthalene floats in the sugar water, while paradichlorobenzene sinks.12PubMed. An algorithm for identifying mothball composition This two-liquid test can be done in seconds and avoids the need for laboratory analysis. In any actual poisoning scenario, though, call poison control before attempting home chemistry. Emergency physicians and toxicologists can guide identification and treatment simultaneously.
Treatment After Mothball Poisoning
There is no antidote that simply reverses mothball poisoning. Treatment is largely supportive and depends on which chemical was involved and which organs are affected. For methemoglobinemia, the standard treatment is intravenous methylene blue, which helps convert methoglobin back to functional hemoglobin. Ascorbic acid (vitamin C) and N-acetylcysteine are also used to counteract oxidative damage and support the body’s antioxidant defenses.13PubMed Central. Naphthalene Poisoning following Ingestion of Mothballs: A Case Report
When kidney failure develops, dialysis or similar renal replacement therapy may be needed. The same case report described a patient who required daily sessions of sustained low-efficiency dialysis for eight hours at a stretch. Severe hemolytic anemia often requires blood transfusions, sometimes repeatedly. In the most critical cases involving children, mechanical ventilation has been necessary to keep the patient breathing while the body clears the toxin. The clinical picture can escalate quickly, particularly if G6PD deficiency is present but undiagnosed.
One complicating factor is that naphthalene is fat-soluble, so it can be stored in body fat and released slowly over days. This means symptoms can appear or worsen well after the initial exposure. Patients who seemed stable after the first day of treatment have sometimes deteriorated on day two or three as stored naphthalene continued to enter the bloodstream. Doctors treating mothball poisoning typically monitor patients for several days even if the initial presentation looks manageable.
Off-Label Use and the Law
A surprisingly common source of mothball-related harm is people using them for purposes the products were never intended for. Because mothball vapors repel insects and have a strong odor, some people scatter them in gardens to deter rabbits, squirrels, or snakes. Others place them in attics, crawl spaces, or under porches to discourage raccoons or rodents. Some people put them in outdoor trash cans, around foundations, or even in potted plants.
All of these uses are illegal. Because naphthalene and paradichlorobenzene are registered pesticides, their label directions carry legal force. Using them in any way not specified on the label violates federal pesticide law.2EDIS. The Facts about Mothballs Labels typically restrict use to enclosed containers with fabric or clothing inside sealed storage areas. Scattering mothballs outdoors exposes soil, groundwater, wildlife, pets, and neighboring properties to pesticide contamination. Both chemicals are toxic to fish and aquatic organisms, and naphthalene does not break down quickly in soil.
Beyond the legal question, outdoor use is also ineffective. The vapors dissipate quickly in open air, so concentrations never get high enough to actually repel animals. You end up contaminating your yard without solving the pest problem. If you need to deter wildlife, physical barriers like fencing or hardware cloth, or products specifically labeled for outdoor animal deterrence, are both legal and far more effective.
Pets and Mothball Exposure
Dogs and cats are vulnerable to mothball poisoning through many of the same routes as children: they may chew on or swallow a mothball, walk across surfaces contaminated with mothball residue and then groom their paws, or breathe concentrated vapors in an enclosed space. Cats are particularly at risk because they lack certain liver enzymes that help metabolize these chemicals, making them more susceptible to toxic buildup. Dogs, meanwhile, are more likely to actually eat a mothball because of their tendency to mouth unfamiliar objects.
Symptoms in pets often include vomiting, lethargy, tremors, and in severe cases seizures. Naphthalene mothballs tend to produce more dramatic hemolytic reactions in animals, similar to what happens in humans. Mothball products can harm people, pets, or wildlife that touch or eat the mothballs or breathe the vapors.2EDIS. The Facts about Mothballs If your pet has been exposed, contact your veterinarian or an animal poison control hotline immediately. Do not wait for symptoms to appear.
Safer Alternatives for Protecting Stored Clothing
If your goal is to protect wool sweaters, suits, or other vulnerable fabrics from moth larvae, there are effective options that do not involve filling your home with pesticide vapor. The key is understanding that it is not adult moths but their larvae that eat fabric. Larvae need undisturbed, dark conditions and are most attracted to fabrics that carry body oils, food stains, or perspiration.
- Clean before storing: Wash or dry-clean all garments before putting them into seasonal storage. Larvae are far less interested in clean fabric.
- Airtight containers: Sealed plastic bins or vacuum-sealed bags physically prevent moths from reaching your clothes. This is the single most effective protection and uses no chemicals at all.
- Cedar: Cedar wood and cedar oil contain compounds that repel moths and may kill very young larvae. Cedar blocks, rings, or lined chests can provide mild protection, though the oils lose potency over time and need refreshing.
- Lavender and herbs: Sachets of dried lavender, rosemary, thyme, or cloves are traditional moth deterrents. The evidence that they kill larvae is weak, but they may discourage adult moths from laying eggs nearby, and they smell far more pleasant than paradichlorobenzene.
- Freezing: Placing garments in a household freezer for several days kills moth eggs and larvae. This works well for items you suspect may already be infested before you store them.
None of these alternatives carry the health risks of mothballs, and a combination of cleaning plus airtight storage is genuinely more effective than chemical mothballs for most home situations. Mothballs work by maintaining a concentrated vapor in a sealed space, and many people fail to achieve that concentration because they place mothballs in open drawers or loosely closed closets. In those settings the chemicals evaporate into your living space without building up enough to kill insects.
When Mothball Smell Lingers on Clothing
If you inherit furniture, vintage clothing, or storage items that reek of mothballs, getting rid of the smell can take effort. The chemicals embed themselves in fabric fibers and off-gas slowly. Simply airing items outdoors in sunlight for several days is the best first step, as UV light helps break down both naphthalene and paradichlorobenzene, and airflow carries the vapor away. Washing with vinegar or baking soda can help for machine-washable items. Dry cleaning is effective for delicate fabrics. Activated charcoal placed in a sealed container with the affected items can absorb residual vapors over time.
The important thing to recognize is that the lingering smell means the chemical is still present and still sublimating. Until the smell is gone, anyone handling or wearing the item is being exposed. Clothing that still smells strongly of mothballs should not be worn, especially by children or pregnant women. And the persistence of the smell in a room after mothballs are removed is a reminder of how readily these chemicals permeate indoor environments. Ventilation, not just removal of the mothball itself, is necessary to clear the air.