If your doctor prescribes lindane to treat a case of head lice or scabies, think twice before getting it filled. The drug, which is a poison that acts on the nervous system, is now known to cause cancer. It is already banned in California but is still being prescribed and sold nationwide. Consumer Reports is urging the Food and Drug Administration to outlaw the use of lindane in the rest of the U.S.

“Lindane is clearly a very hazardous pesticide,” says Michael Hansen, Ph.D., a senior scientist at Consumer Reports. “It can be absorbed through the scalp, and we are particularly concerned about its use, especially in treating children.”

In June 2015 the World Health Organization’s International Agency on Cancer Research (WHO IARC) reviewed the most recent data on lindane and moved it from being classified as “possibly carcinogenic to humans” to the highest category of concern—“known to cause human cancer (Class A1).” In 2014 the U.S. Agricultural Health Study reported that exposure to lindane could significantly increase the risk of non-Hodgkin’s lymphoma. "Less-toxic treatment alternatives exist for both lice and scabies infections,” Hansen says.

Head lice size shown against a penny.
Photo: Courtesy of Centers for Disease Control and Prevention

Lindane is used as a shampoo to kill lice (sesame-seed-size wingless insects that feed on human blood) or lotion to kill scabies mites (tiny parasites that burrow into the skin). It has been reported to cause dizziness, headaches, diarrhea, nausea, vomiting, seizures and, in rare cases, death.

It's the only lice treatment that carries the FDA’s “black-box warning,” indicating a significant risk of serious or life-threatening side effects. But in 2014 doctors wrote and patients filled more than 37,000 prescriptions for it (23,083 for scabies and 14,677 for lice), according to data provided to Consumer Reports by IMS Health, a global information and technology services company.

Increasing concern

Lindane has been registered since 1951 as a prescription treatment for lice and scabies and has been used on U.S. farms to get rid of insects. The WHO IARC classification is the latest in a series of actions taken against the chemical over the years:

• In 1981 Consumer Reports submitted its first petition urging the FDA to ban lindane for lice control.

• In 2002 California banned the use of lindane for treating lice and scabies.

• In 2009 the American Academy of Pediatrics stopped recommending lindane as a lice and scabies treatment.

Genetic resistance

The Centers for Disease Control and Prevention points out that overuse, misuse, or accidentally swallowing lindane can be toxic to the brain and other parts of the nervous system. Not only is lindane dangerous, but it’s also not very effective. Because the product has been around for decades, many lice have evolved to become genetically resistant to the drug. Several studies have confirmed this, most notably one published in the Archives of Dermatology in 2002 that found lindane to be the least effective pharmaceutical treatment for head lice.

What you should do. Consumer Reports’ experts say the safest way to eradicate lice and treat scabies is to avoid pesticide products. Instead, to find live bugs, comb through hair soaked in conditioner or olive oil using a metal nit comb with closely spaced teeth (think flea comb), and work in bright light. This is the most effective treatment, according to a 2009 study in the Archives of Dermatology. Continue to comb out your child’s hair every day until no live lice are seen and then every few days for about a month.

“The chemicals on the market don’t kill 100 percent of the eggs,” Hansen says. “Physical removal is the safest and surest method of getting rid of lice.”