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Mothballs Can Be Poisonous

The Bottom Line

Mothballs are pesticides. They can be poisonous if swallowed or if large amounts of fumes are inhaled.

The Full Story

Once they're out of the box, mothballs look like candy to children. If you're unpacking your winter clothes now, the mothballs are loose and the box is not around.

But if you look at a box of mothballs, it is clear that mothballs are pesticides. There is a lot of required information about how and when to use them, what to do if someone swallows them, and how to dispose of them properly. This information is required by law, because mothballs ARE pesticides.

An active ingredient in some mothballs is naphthalene. If swallowed, naphthalene can damage red blood cells, causing kidney damage and many other problems. It can affect how blood carries oxygen to the heart, brain, and other organs. It can also cause nausea, vomiting, abdominal pain, seizures and coma. Breathing in the fumes over a period of time can cause poisoning, too. Children have been poisoned by wearing wool clothing stored with naphthalene mothballs, although this is rare.

The active ingredient in other mothballs is paradichlorobenzene. This is less toxic, but the mothballs and fumes can still be irritating or even poisonous.

Whether you are getting your winter clothes ready for upcoming cold weather or storing boxes of mothballs, there are some safety tips to prevent family members and pets from being poisoned.

  • Be sure that loose mothballs and boxes of mothballs are kept where children cannot find them.
  • Follow all label directions carefully. These products are legal to use on and around clothing. They are NOT legal to use loose in the attic, in the eaves, or on the ground outside in an attempt to repel animals.
  • Wash clothing and bedding that has been stored in mothballs before wearing or using it. (Some authorities believe that it's hard to wash naphthalene out of fabrics.)
  • Dispose of mothballs with other household hazardous waste. (Hazardous waste collection sites differ by county.)
  • If you think that anyone has swallowed mothballs, get guidance from Poison Control right away. Use the webPOISONCONTROL® online tool or call 1-800-222-1222 any time of the day. Both options will tell you exactly what to do.

Rose Ann Gould Soloway, RN, BSN, MSEd, DABAT emerita
Clinical Toxicologist

For More Information

Let's talk about pesticides infographic


Bates N. Mothball poisoning. Emergency nurse. 2002;10:24-28.


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Prevention Tips

If you choose to use mothballs:

  • Follow label directions carefully.
  • Keep mothballs out of reach of children and pets.

This Really Happened

Case 1: A 19-month-old healthy boy swallowed some mothballs containing paradichlorobenzene. The child was brought to the emergency room, where he was given activated charcoal. He seemed fine and his physical examination was normal. Three days later, his family took him back to the emergency room. His skin was yellow and he was fussy. His heart rate was very fast and his hemoglobin (reflecting red blood cells) was very low. The mothballs had caused his red blood cells to rupture. He was given a transfusion of packed red blood cells and admitted to the hospital. His hemoglobin level rose and the child recovered without additional problems.

Reference: Sillery JJ, Lichenstein R, Barruets F Jr., Teshome G. Hemolytic anemia induced by ingestion of paradichlorobenzene mothballs. Pediatr Emer Care. 2009;25: 252-254.

Case 2: A 6-month-old 20-pound dog swallowed an unknown quantity of naphthalene mothballs that someone had spread all across a lawn. The time of the ingestion was unknown. The veterinarian consulted Poison Control when the dog was brought in lethargic, anemic, vomiting blood, and bleeding into his abdomen. Poison Control discussed the use of methylene blue (an antidote that can treat an abnormal form of hemoglobin that cannot carry oxygen properly, which may result from ingestion of naphthalene), if the veterinarian could test for this abnormal hemoglobin, as well as blood transfusions and intravenous fluids. The dog however was too sick and had to be euthanized.