According to MedlinePlus, tea tree oil is a possible effective treatment for athlete's foot, fungal infections in the nails and mild-to-moderate acne. It is also used to treat yeast infections, thrush, lice, gingivitis, hemorrhoids, dandruff, cold sores, eye infections and bad breath, although there is insufficient evidence available to rate its effectiveness for treating these issues.
Some people add tea tree oil to bath water to treat a cough, bronchial congestion or pulmonary inflammation, and the oil has also been used topically to prevent infections in cuts, abrasions, burns, insect bites and boils, notes MedlinePlus. Many types of hygiene and body care products include tea tree oil, including shampoos, bar soaps, toothpaste, skin creams, essential oils and lip balms.
WebMD states that tea tree oil is generally safe to use as a topical treatment, and when applied directly to the skin in its pure form, it seldom causes irritation. However, the oil can be toxic if taken orally, and it is not recommended for use in ears as it has the potential to cause inner-ear damage. Because the U.S. Food and Drug Administration does not regulate the use of tea tree oil, it can be sold through various means even though there is limited research available as to how well it actually works.