Searching for a quick fix for a case of acne, athlete’s foot, or toenail fungus might lead you to products that contain tea tree oil—a liquid that is extracted from the leaves of the Melaleuca alterni­folia tree. Tea tree oil can also be found in over-the-counter items that promise to freshen breath and remove dental plaque. But does it work? Here's what our experts say tea tree oil can—and can't—do for these conditions.

Tea Tree Oil for Athlete's Foot

“Tea tree oil may be effective for milder cases of athlete's foot,” says Jessica J. Krant, M.D., M.P.H., clinical assistant professor of dermatology at SUNY Downstate Medical Center in Brooklyn, N.Y., and a member of Consumer Reports’ medical advisory board. That’s because it is known to be antiseptic, mildly antifungal, and mildly antibacterial, she says.

In fact, a study published in the Australasian Journal of Dermatology in 2002 found that twice-daily use of a 25 or 50 percent tea tree solution for four weeks cleared up athlete’s foot for more than half the people who used it—although nearly four percent of study participants who used the tea tree oil solution also developed an itchy rash.

While these results seem encouraging, there’s no guarantee that consumers will get the same results from the tea tree oil products they buy. That’s because study researchers use ingredients that are purified and analyzed to ensure that they contain exact concentrations of high-quality tea tree oil. But tea tree oil products aren’t regulated in the way that medications are, so there’s no way to be sure that a product from the drugstore contains the ingredients that will have the desired effect, says Krant.

It’s also important to note that other studies have found tea tree oil to be less effective at treating athlete’s foot than over-the-counter antifungal medications such as tolnaftate (Tinactin and generic).

Tea Tree Oil for Toenail Fungus

“Tea tree oil is unlikely to fully cure a well-established toenail fungus infection, since the infection tends to be based in the nail matrix, or ‘root’, underneath the nail fold (cuticle),” Krant says. But prescription drugs for toenail fungus are not always effective. “Topical prescription creams and liquids work about 10 to 15 percent of the time when used over many months on true toenail fungus,” says Krant.

Tea tree oil may have a similar rate of effectiveness: A study published in the Journal of Family Practice in 1994 comparing tea tree oil with clotrimazole, a common antifungal medication, found that the two treatments were almost equally successful in treating the condition.

Tea Tree Oil for Acne

“Tea tree oil, when properly diluted, may help mild to moderate acne,” Krant says. Experts believe that the liquid’s acne-fighting power comes from its antimicrobial and anti-inflammatory properties.

Although more research needs to be done, existing studies are promising. A review of seven studies, including three double-blind trials, published in the International Journal of Antimicrobial Agents in 2015, concluded that products containing at least 5 percent tea tree oil, applied twice daily for multiple weeks, is likely to reduce acne. The researchers also concluded that people experienced similar adverse reactions to tea tree oil as they did to other medicated acne treatments, such as dryness, stinging, and burning.

If tea tree oil alone isn’t strong enough to clear up acne, combining it with other medications, such as benzoyl peroxide or retinoids (retinol, tretinoin) may do the trick, Krant says. “Retinoids add benefit by working to exfoliate and normalize cell development and turnover rates,” she says—which tea tree oil does not appear to do. But keep in mind that using tea tree oil to treat acne can also cause rashes.

Should You Try Tea Tree Oil?

It might be worth trying tea tree oil for athlete’s foot, toenail fungus, or acne. But skip tea tree oil products marketed to combat bad breath, tooth plaque, and gum disease. In fact, says Krant, don't use tea tree oil for any oral conditions; it may be unsafe to eat or drink. And if you use it on your skin, stop the treatment immediately if you notice that it's causing irritation or a rash—some people are allergic to tea tree oil.