Itch Stops Here

Topical lice treatment with ivermectin works safely and effectively

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) It can be hard to kill the tiny bloodsuckers invading kids' hair. And with the chemicals involved, safety of the lice treatment can come into question. But a new study has found that on-the-hair treatments with ivermectin can be used safely and it works well.

Lower concentrations of the ingredient were found in their blood compared to taking the treatment orally, which makes the shampoo a more viable option for getting rid of the bugs.

"Tell kids not to share hair accessories."

Researchers led by Lydie Hazan, MD, a lead investigator and founder of Axis Clinical Trials, aimed to see how safe ivermectin, commonly known as stromectol, is in treating head lice on young children. Stromectol is more often used to fight parasite infections in the skin and intestines.

The study involved 30 children between 6 months and 3 years old with head lice; 4 ounces of ivermectin was applied to their hair for 10 minutes. Three-quarters of the children were girls and about 93 percent were of Hispanic descent. After rinsing, participants were asked not to wash their hair for two days to allow the product to fully absorb into the skin.

Blood samples were collected half an hour after rinsing as well as an hour and six hours later. Researchers also collected samples two days and eight days after using the product. They also surveyed whether patients' eyes and skin were irritated. If patients still had lice after treatment, they were given another over-the-counter treatment to use.

At the same time, more than 200 healthy adults were given a set of patches containing different ingredients. One contained ivermectin and the other had a basic lotion to compare how sensitive the skin is towards the ivermectin. The patches were worn throughout the day with new ones given daily for three weeks. Before using the treatment, half the patients had an itchy scalp.

Only 10 percent of the children continued to feel itchy six hours after treatment, researchers found. That lowered to a little over 3 percent two days later and all were itch-free by day 8.

About 97 percent were lice-free by the second day. One and two weeks later, about 90 percent were still lice-free.

Researchers found less than 1 mg/mL of ivermectin in the blood samples of 19 children. A week after treatment, only two children had trace amounts of the treatment left in their body.

Six of the children experienced minor changes in their heart's rhythm. And among the adults, 218 of the 220 tested were not sensitive to the treatment.

"The absence of dermal irritation and contact sensitization in the patch test indicate that repeated treatments, if needed, may be administered," researchers wrote in their report.

The authors note that their findings should be applied carefully to the rest of the population since they mainly studied Hispanic children. Two of the authors were consultants and employees for Sanofi Pasteur and Topaz Pharmaceuticals. The study was published online November 7 in the journal Pediatric Dermatology. Funding information was not available.

Reviewed by: 
Review Date: 
December 2, 2012
Last Updated:
December 31, 2013