Head lice can affect anyone, but it's most common in children. An estimated 6 to 12 million U.S. children suffer from lice infestations every year, according to the Centers for Disease Control and Prevention. Although a variety of over-the-counter (OTC) and prescription lice treatments are available, their effectiveness has waned over time. This medication resistance, coupled with the desire for more natural and safe options, has increased the demand for alternative ways to treat lice. One such natural treatment is tea tree oil, which is usually added to shampoo or diluted and applied on the hair and scalp.
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Head Lice 101
Head lice are tiny, wingless, blood-sucking insects that live on the human scalp. Each day, female lice can lay up to 10 eggs -- or nits -- on the hair shaft near the scalp, and these eggs hatch within 7 to 10 days. If unchecked, infestations can develop rapidly. These insects do not jump from person to person, but are easily spread through physical contact, such as sharing hats, combs or pillows. Head lice is treated by OTC, or if needed, prescription lotions or shampoos that contain low concentrations of insecticides or other chemicals. Parents concerned about the use of these chemicals tend to opt for more natural treatments, such as tea tree oil (TTO).
TTO, also called melaleuca oil, is an essential oil derived from the leaves of the native Australian plant Melaleuca alternifolia. A concentration of aromatic and therapeutic plant constituents, TTO is known to have insecticidal properties, among other benefits, and a research study published in the November 2012 issue of “Parasitology Research” appears to confirm this. This laboratory study exposed lice and nits to different concentrations of TTO and nerolidol, another essential oil. When lice were exposed to a 1 percent TTO solution for 30 minutes, 100 percent of the lice died.
While these study results are impressive, in order to be effective, lice treatment needs to also kill the nits or prevent them from hatching. This same study in “Parasitology Research” tested TTO concentrations between 1 and 8 percent, and found that none of these killed 100 percent of the nits within 7 days. The most effective treatment studied was exposing nits to a mixture of 0.5 percent TTO and 1 percent nerolidol -- with 100 percent of eggs failing to hatch after 5 days. More research is needed to determine if TTO alone can be effective in treating lice and nits, and to understand safety of using this treatment on children.
Treating head lice in humans can be more challenging compared to exposing lice and nits to essential oils in a laboratory, and research still needs to clarify if real-life use of TTO can be effective. For instance, if TTO is added to shampoo, as suggested for lice treatment, the scalp and hair may not be exposed to this oil long enough, or at concentrations high enough, to kill both lice and nits. Applying diluted oil to the hair and scalp for a period of time may work better, since one of TTO's mechanisms of action is to suffocate lice, but the optimal time frame is not known. Due to limited research on effectiveness -- particularly in killing nits -- tea tree oil is not the best option for large lice infestations, or when lice is resistant to treatment. In these cases, seek treatment advice from your doctor.
Although TTO may be considered a chemical-free, safe option, essential oils are highly concentrated plant chemicals, and irritation or allergies can occur. When used topically, essential oils are safest when diluted in a carrier oil. A January 2006 report in “Clinical Microbiology Reviews” outlined that concentrations of 10 percent or less TTO -- or a maximum strength of 1 part TTO mixed with 10 parts of carrier oil -- are generally well tolerated when applied to the skin. However, adequate safety data is not available regarding its use in children, pregnant women or in people with sensitive skin, so it's best for these groups to seek medical advice before using. Treating lice can be a challenge -- and can be time consuming. If you choose to use alternative therapies such as TTO, consult a doctor if your treatment is not successful within a few weeks, and discontinue use if irritation or a rash occurs. Tea tree oil can be toxic if ingested, so do not consume, and keep TTO out of the reach of young children.
Reviewed by Kay Peck MPH RD