Captain Cook named this tree after finding that its aromatic, resinous leaves made a satisfying substitute for proper tea. One hundred and fifty years later, an Australian government chemist named A.R. Penfold studied tea tree leaves and discovered their antiseptic properties. Tea tree oil subsequently became a standard treatment in Australia for the prevention and treatment of wound infections. During World War II, the Australian government classified tea tree oil as an essential commodity and exempted producers from military service.

However, tea tree oil fell out of favor when antibiotics became widely available.

What Is Tea Tree Used for Today?

Tea tree oil can kill many bacteria, viruses, and fungi on contact.1,2,12 This makes it an antiseptic, like betadine, hydrogen peroxide, and many other essential oils. It is not an antibiotic in the common sense, because an antibiotic is absorbed throughout the body.

Preliminary double-blind studies suggest that tea tree oil might be useful for athlete's footand other fungal infections of the skin and nails.3,4,13

One double-blind study found tea tree oil helpful for acne.20

Another double-blind study found that tea tree oil gel may reduce gum inflammation in people with periodontal disease.15

A single-blind study found evidence that tea tree oil may be helpful for dandruff.14Tea tree oil plus lavender oil may also be an effective treatment for head lice.21

Tea tree oil may be as effective as standard antiseptics for removing resistant strains of staph bacteria from the skin of hospitalized patients.16-18Note: This does not mean tea tree oil is effective as an antibiotic for staph bacteria. It is an antiseptic. Antiseptics work on the surface of the body, while antibiotics work from within.

Additionally, tea tree oil has been proposed as a treatment for vaginal infections, thrush, and oral herpes(cold sores).1,6,7,12 However, there is no reliable evidence to indicate that it is effective for these purposes.

What Is the Scientific Evidence for Tea Tree?

Athlete’s Foot

In a double-blind, placebo-controlled trial, 158 people with athlete’s footwere treated with placebo, 25% tea tree oil solution, or 50% tea tree oil solution, applied twice daily for 4 weeks.13 The results showed that the two tea tree oil solutions were more effective than placebo at eradicating infection. In the 50% tea tree oil group, 64% were cured; in the 25% tea tree oil group, 55% were cured; in the placebo group, 31% were cured. These differences were statistically significant. A few people developed dermatitis in response to the tea tree oil and had to drop out of the study, but most people did not experience any significant side effects.

Another double-blind, placebo-controlled trial followed 104 people with athlete’s foot who were given either a 10% tea tree oil cream, the standard drug tolnaftate, or placebo.8 The results showed that tea tree oil reduced the symptoms of athlete's foot more effectively than placebo but less effectively than tolnaftate. Neither treatment cured the infection in 100% of the cases, but each treatment cured many cases.

A third double-blind study followed 112 people with fungal infections of the toenails, comparing 100% tea tree oil to a standard topical antifungal treatment, clotrimazole.9 The results showed equivalent benefits; however, because topical clotrimazole is not regarded as a particularly effective treatment for this condition, the results mean little.

Dandruff

In a 4-week, placebo-controlled study of 126 people with mild to moderate dandruff, use of 5% tea tree oil shampoo significantly reduced dandruff symptoms.14 Unfortunately, this study was not double-blind: the researchers knew which participants were receiving tea tree oil and which were receiving placebo. For this reason, its results cannot be taken as completely reliable. (For more information on why double-blinding matters, see Why Does This Database Rely on Double-blind Studies?)

Head Lice

Head lice is a common condition in children. It is often treated with insecticides, like pyrethrins and piperonyl butoxide, that are applied to the scalp. Tea tree oil has been studied as a possible alternative.21 In one trial, 123 children (aged 4-12 years) were randomized to one of three groups: tea tree oil plus lavender oil, a head lice product that works by suffocating the lice, or insecticides (pyrethrins and piperonyl butoxide). The day after being treated, almost all of the children in the tea tree plus lavender oil group, as well as the suffocation product group, were lice-free, compared to only 25% of those in the insecticides group (a significant difference).

Acne

The best evidence for benefits with tea tree oil as a treatment for acnecomes from a randomized double-blind clinical trial of 60 people with mild to moderate acne symptoms.20 In this study, participants were divided into two groups and treated with placebo or 5% tea tree oil gel. Over the 45-day study period, researchers evaluated acne severity in two ways: by means of counting the total number of acne lesions (TLC) and also by rating acne severity on a standardized index (ASI). The results showed that tea tree oil gel was significantly more effective than placebo at reducing both the number of acne lesions and their severity.

Dosage

Tea tree preparations contain various percentages of tea tree oil. For treating acne, the typical strength is 5% to 15%; for fungal infections, 70% to 100% is usually used; and for use as a vaginal douche (with medical supervision), 1% to 40% concentrations have been used. It is usually applied 2 to 3 times daily, until symptoms resolve. However, tea tree oil can be irritating to the skin, so start with low concentrations until you know your tolerance.

The best tea tree products contain oil from the alternifolia species of Melaleucaonly, standardized to contain not more than 10% cineole (an irritant) and at least 30% terpinen-4-ol. Oil from a specially bred variant of tea tree may have increased activity against microorganisms, while irritating the skin less.10

Safety Issues

When used topically, tea tree oil is thought to be safe. However, it can cause allergic inflammation of the skin.11,13In addition, one report suggests that a combination of lavender oil and tea tree oil applied topically caused gynecomastia (breast enlargement) in three young boys.19 The researchers who published this report also state that testing of tea tree oil revealed estrogenic (estrogen-like) and antiandrogenic (testosterone-blocking) effects. However, a literature search failed to find any other published reports that corroborate this claim.

Like other essential oils, tea tree oil can be toxic if taken orally in excessive doses.

Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.