The medical treatment generally recommended for head lice is a special shampoo that contains the chemical permethrin, such as over-the-counter remedies Rid and Nix. (Or for light infestations, careful combing and manual removal may suffice.)
The medical community has determined permethrin to be highly effective and safe with few side effects, though it is not perfect in either regard. There have been reports of an increase in permethrin-resistant lice, thus reducing the chemical’s effectiveness. There are also claims from some alternative medicine proponents that the use of permethrin is associated with an increase in brain cancer.
To deal with permethrin-resistant lice, one alternative is to use stronger chemicals, but of course this only increases concerns about side effects.
Thus many people turn to home remedies and alternative medicine cures, including mayonnaise, Vaseline, olive oil or motor oil.
One such remedy that has become increasingly popular in recent years is tea tree oil. Tea tree oil is a greenish yellow oil distilled from the leaves of an Australian species of tree, with a strong camphor-like odor.
There is no single accepted method for using a home remedy like tea tree oil, only informal recommendations based on the trial and error of personal experience. But a typical treatment would be to mix 1-2 teaspoons of tea tree oil with shampoo, to shampoo the hair with it, to leave it in with a shower cap tightly covering the head for one hour, to wash it off, and then to go through the hair carefully with a nit comb to remove the lice and nits.
So, is it safe, and is it effective?
Tea tree oil is toxic to the liver in large doses. It is not recommended for babies, young children, or pregnant women. In the small doses used in shampoo for head lice, it should be fine for people outside of these categories. It can provoke an allergic reaction in some people however, so it is a good idea as a precaution to first swab a small amount to the wrist or the back of the leg, and only to proceed with using it if there is no adverse reaction within a few hours.
Its effectiveness is uncertain but promising. As with home remedies and alternative medicine in general, there is no shortage of anecdotal evidence in its favor. But tea tree oil also has some studies in its favor, including one from Australia where it even outperformed permethrin. There has not been enough evidence as of yet for tea tree oil to gain broad acceptance in the medical community as a treatment for head lice, but nor can it be claimed it is unambiguously bogus.
Perhaps it is best to say that there is significant but inconclusive evidence in its favor as a treatment for head lice.
Vincent Iannelli, “Head Lice Treatments for Kids.” About.com.
Dr. Patrick Massey, “Tea Tree Gel Gets Rid of Head Lice.” Daily Herald.
“Alternative Treatments: What the NPA Is Saying About Mayonnaise, Vaseline and Tea Tree Oil.” Headlice.org.
“What is Tea Tree Oil?” Wise Geek.