Mothballs have exactly one approved use: killing clothes moths and other fabric-eating insects inside sealed containers. Despite decades of folk wisdom suggesting otherwise, mothballs are registered pesticides with narrow legal labeling, and using them any other way is both ineffective and potentially dangerous. That said, understanding how they work within their intended purpose, and why so many off-label uses are a bad idea, can help you protect your clothing without putting your household at risk.
The One Labeled Use: Killing Clothes Moths
Mothballs are designed to protect stored fabrics, particularly wool, silk, and other natural fibers that clothes moth larvae feed on. The active ingredients, either naphthalene or paradichlorobenzene, slowly release fumes that build up inside an enclosed space and kill moths at every life stage. The key word is “enclosed.” Mothball labels direct you to place them inside a tightly sealed container, like a storage bin with a secure lid, a garment bag that zips shut, or a trunk that closes firmly. The vapors need to accumulate to a lethal concentration for the moths, and that only happens in an airtight space.
If you toss mothballs loosely into a closet or scatter them on shelves, the fumes dissipate into your living space instead of concentrating around your clothes. That means they won’t kill moths effectively, and you’ll be breathing pesticide vapors in the meantime.
Common Misuses That Don’t Work
Mothballs are one of the most commonly misused household products. People scatter them in attics, crawl spaces, gardens, and along foundations to repel snakes, mice, squirrels, bats, and insects. None of these uses appear on the product label, which makes them illegal under federal pesticide law. More importantly, they don’t work. The National Pesticide Information Center notes that mothballs have “little effect on snakes” despite being widely believed to repel them. The same is true for rodents and most other animals. The concentration of fumes in an open or ventilated area is far too low to repel anything.
Using mothballs outdoors introduces pesticide chemicals into soil, groundwater, and the air around your home. Naphthalene is a hydrocarbon derived from coal tar or crude oil, and it doesn’t belong in garden beds or around your porch. If a product’s label doesn’t list a specific use, that use isn’t just unapproved. It’s a violation of federal law.
Why Mothball Fumes Are a Real Health Concern
The reason labels restrict mothballs to sealed containers isn’t just about effectiveness. It’s about safety. Breathing naphthalene fumes over time can cause headaches, nausea, confusion, and drowsiness. In more serious cases, naphthalene damages red blood cells, a process called hemolytic anemia. This reduces your blood’s ability to carry oxygen and can lead to jaundice (yellowing of the skin), dark or bloody urine, rapid heart rate, and kidney damage.
People with a genetic condition called G6PD deficiency are especially vulnerable. This enzyme deficiency is more common in men and in people of African or Mediterranean descent. Newborns are also at higher risk because their bodies are less efficient at breaking down and clearing naphthalene. In documented cases, infants developed hemolytic anemia simply from wearing clothes or sleeping in bedding that had been stored with naphthalene mothballs.
Paradichlorobenzene, the other common active ingredient, is generally less acutely toxic. Small accidental exposures may cause only mild irritation, nausea, or a headache. But large or prolonged exposure has been linked to impaired balance, muscle weakness, behavioral changes, and the same red blood cell destruction seen with naphthalene. In one published case, a 19-month-old who swallowed paradichlorobenzene mothballs developed severe anemia requiring a blood transfusion three days after ingestion.
Risks to Children and Pets
Mothballs are small, round, and sometimes white or brightly colored, which makes them look like candy or toys to young children. Swallowing even one naphthalene mothball can cause vomiting, abdominal pain, seizures, and coma. Naphthalene can also trigger the formation of methemoglobin, an abnormal form of hemoglobin that cannot carry oxygen. When methemoglobin levels rise, oxygen delivery to the heart, brain, and other organs drops.
Pets face similar risks. Dogs in particular may eat mothballs they find on the floor or in open containers. If you use mothballs at all, they need to be inside sealed containers that children and animals cannot open, and those containers should be stored out of reach.
Safer Ways to Protect Stored Clothing
If your goal is protecting wool sweaters, suits, or blankets from moth damage, several alternatives work without filling your home with pesticide fumes.
- Cedar wood. Cedar blocks, rings, and chips release natural oils that repel clothes moths. They work best in enclosed spaces like drawers, garment bags, and storage bins. The scent fades over time, but light sanding or a cedar oil spray refreshes the wood’s surface.
- Pheromone traps. Sticky traps baited with clothes moth pheromones attract and capture adult male moths, breaking the breeding cycle. They’re odorless, non-toxic, and safe around pets and children. They won’t eliminate an active infestation on their own, but they’re excellent for monitoring and reducing moth populations in closets.
- Lavender sachets. Dried lavender or lavender-and-cedar sachets repel moths and leave clothes smelling fresh. They’re a good option for drawers and smaller storage spaces.
- Clean before storing. Clothes moths are attracted to body oils, food stains, and sweat on fabric. Washing or dry cleaning garments before putting them into long-term storage removes what moths are actually feeding on and significantly reduces your risk of damage.
- Airtight storage. Vacuum-sealed bags or bins with tight-fitting lids physically prevent moths from reaching your fabrics. This is the simplest and most effective approach, especially for seasonal clothing you won’t touch for months.
How to Handle and Dispose of Mothballs
If you already have mothballs in your home, handle them with care. Wear gloves when touching them, and wash your hands thoroughly afterward. Air out any clothing that has been stored with mothballs before wearing it, ideally outdoors or in a well-ventilated room for several hours.
Don’t throw unused mothballs in the regular trash. They’re classified as household hazardous waste in most states. Many municipalities run periodic hazardous waste collection events where you can drop off mothballs, old pesticides, and similar products for free. Check with your local public works department or solid waste authority for the next collection date in your area. If mothballs are left in packaging, keep them sealed until you can dispose of them properly.