Probably one of the most recommended home treatment and preventive products for head lice is tea tree oil. How effective is it, and are there potential side effects?
Tea tree oil, also known as Melaleuca oil, was originally derived (and still is today) from the leaves of the Australian tea tree shrub (Melaleuca alternifolia). Since the 1980s, production has expanded to other regions of the world and is now from different species, all known as “tea tree oil”. For example, Melaleuca armillaris and Melaleuca styphelioides hail from Tunisia and Egypt, while Melaleuca quinquenervia comes from the United States. 
Australian Aborigines have used the healing properties of the Melaleuca alternifolia plant for years. In the 1920s, an Australian chemist by the name of Arthur Penfold, first published reports of tea tree oil’s antimicrobial activity. Today, although scientific data is insufficient, anecdotal evidence suggests that tea tree oil’s benefits include antibacterial, antifungal, antiviral, and antiprotozoal properties (protozoa are one-celled organisms which can multiply in humans and create serious infections). 
But what about head lice? Does tea tree oil work in killing adult lice, nymphs (babies, toddlers & teenage lice) and nits (eggs)? Bottom line, there is no product, device or tool on the market today that kills lice and nits 100%. Period.
OK, if no product, device or tool kills lice or nits 100%, then is tea tree oil safe and the best product to get rid of a head lice infestation or ward one off? After all, Australian Aborigines have used the plant for ages. And it’s an oil derived from a natural plant. It has to be better than using OTC chemicals that are toxic and no longer work, right?
As for the Aborigines, they used the whole plant, not the processed oil. OTC pesticide products are indeed ineffective nowadays, due to the increased resistance of lice in the last 20 years . And yes, tea tree oil is a natural derivative of the plant. However, most people don’t realize that there are potential side effects that you might want to consider before using.
There is evidence that tea tree and lavender oils, when used repeatedly on pre-pubescent boys, can cause enlarged breast growth. Research is once again limited, but one study concluded that tea tree and lavender oils may have properties that disrupt hormones in young boys   . No known studies have been performed on young girls at this time.
Tea tree oil can also irritate your skin, so when used in strong dosages or in repeated low dose formulae, the result can be an annoying itchy head which can leave you wondering, do I have lice again?! PTSD from a head lice infestation is very real. Tea tree oil is quite toxic when swallowed so please be very careful when using around children.
If this information is enough to deter you from wanting to use these oils, then what is a better option for treating and preventing head lice? We recommend mint. Mint is a strong scent that the bugs just don’t like. Mint-based sprays, shampoos and conditioners are great repellents. Naturally occurring enzyme-based mint treatment products are also very effective at-home treatment options. Again, no product is 100%, so you can still get lice using these preventives. You can still have lice using the treatment products if you don’t get every last 2 nits out of your hair. But using these products in conjunction with a great lice comb is the most effective means of dealing with lice. For more information, check out our products listed on our website.
Lice Spies are professionally trained and certified through the Shepherd Institute. We provide safe, non-toxic, natural head lice checks, treatment services, DIY & preventive products. Located on the corner of Edmonds Way and 236th Street Southwest in Edmonds, WA, appointments can be booked online, anytime of day or night at www.licespies.com.
- Wikipedia: Tea tree oil. https://en.wikipedia.org/wiki/Tea_tree_oil
- Melaleuca alternifolia (Tea Tree) Oil: a Review of Antimicrobial and Other Medicinal Properties by F. Carson, K. A. Hammer, and T. V. Riley. Clinical Microbiol Reviews, v.19(1); 2006 JanPMC1360273.
- Lice Spies: http://licespies.com/6-month-head-lice-battle-otc-prescription-pesticides/
- Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils by Derek V. Henley, Ph.D., Natasha Lipson, M.D., Kenneth S. Korach, Ph.D., and Clifford A. Bloch, M.D.; The New England Journal of Medicine: February 1, 2007.
- The Mayo Clinic: Safety and side effects of tea tree oil. https://www.mayoclinic.org/drugs-supplements-tea-tree-oil/art-20364246?pg=2
- WebMD.com: Tea tree oil side effects and safety. https://www.webmd.com/vitamins-supplements/ingredientmono-113-TEA+TREE+OIL.aspx