Tea tree oil is an essential oil derived from Australian tea tree leaves. You may also know it as melaleuca oil. “We turn to it for its antiseptic, antibacterial, and anti-inflammatory properties, and there are a lot of ways it can be utilized on skin, hair, and nails as a natural treatment,” says Jennifer Holman, MD, a board-certified dermatologist and the regional president of U.S. Dermatology Partners in East and South Texas.

Tea tree oil is available as a pure essential oil. It may also be used in personal-care products, particularly those that aim to prevent or reduce acne, including cleansers, toners, body washes, gels, lotions, and other treatments.

A word of warning: Never ingest tea tree oil, because it’s poisonous if swallowed. Tea tree oil should only be applied topically.

Read on to learn more about this popular oil and its uses on the face and skin.

The main benefit of tea tree oil is its pimple-fighting ability. For that reason, tea tree oil may be a good choice for people with acne, says Deirdre Hooper, MD, a board-certified dermatologist with Audubon Dermatology in New Orleans.

To understand why, consider the four main contributors to the development of acne: inflammation, bacteria, hormones, and sebum, says Dr. Hooper. Tea tree oil has antibacterial and anti-inflammatory properties, so it addresses two of those main players.

Hooper points to past research that compared tea tree oil with benzoyl peroxide, a common topical acne treatment. This small study found that tea tree was equally effective at reducing acne-related inflammation, she explains. And while tea tree was slower acting (meaning results took longer to see), it led to fewer unwanted skin reactions than the benzoyl peroxide.Other research supports these earlier results. A review concluded that of six studies analyzed, all of which looked at people who had mild to moderate acne, five found that a 5 percent tea tree oil product applied twice daily reduced acne lesions by 23.7 to 62.1 percent after four to eight weeks. (That said, not all of the studies examined were double-blind randomized trials, so more research is likely needed.)

First, keep in mind that tea tree oil should only be used topically and that ingesting the ingredient isn’t safe. It’s a good idea to try a patch test first, by applying the oil on the inside of your forearm and waiting a day or two to see if a rash forms.

To get started with adding tea tree oil to your skin-care routine, either purchase a skin-care product that contains tea tree oil or use the essential oil itself, says Dr. Holman. To use the essential oil, it’s very important to dilute it first by mixing it with a carrier, such as a witch hazel toner or moisturizer. (Applying the undiluted oil can cause an allergic reaction on the skin, Holman says.)

Holman recommends using three drops of tea tree oil to two ounces (oz) of product. You can use tea tree oil in the morning or at night. Combine tea tree oil with a witch hazel toner if you have acne, which can be done after cleansing your skin, or combine the oil with a moisturizer (such as coconut oil) as a last step in your evening skin-care routine, if you also have dry or sensitive skin.

It can make skin more sun sensitive, says Holman. For that reason, don’t apply it immediately before going outdoors. No matter what skin-care products you’re using, though, it’s always important to apply a broad-spectrum sunscreen with at least SPF 30 to your face every morning.

Hooper recommends that people with acne-prone skin apply a product containing tea tree oil once or twice a day, focusing on pimple trouble zones like the chin or T-zone. You can apply this product in the morning, at night, or both, but choose a time when you’re most likely to consistently apply it, she adds. Use the ingredient routinely to see the best results, Hooper suggests.

She also points out that it may take a few months to see real improvement in your skin, so give it 12 weeks of consistent use before assessing the effects on your acne. (That’s because pimple formation can begin months before the red bump appears, she says.)

If, after 12 weeks, you’re not seeing results, you may need a stronger acne product. A board-certified dermatologist can help develop an acne-fighting plan appropriate for your skin. Tea tree oil is also better suited for mild acne, and is likely not strong enough if you have more moderate or severe forms of the skin condition, says Hooper.

You can use tea tree oil as a natural treatment for nail fungus or athlete’s foot, says Holman, though it will not be as effective as a prescription product. There’s some in vitro research that shows tea tree oil inhibits the growth of fungus in onychomycosis, the name for the fungal infection of fingernails and toenails that causes thick, discolored, distorted, and even smelly nails. That said, more research is needed to evaluate it. If the condition is not resolving or is getting worse, seek your doctor’s advice.

If you are using tea tree oil to treat a nail fungal infection, dilute it in a carrier oil, such as coconut oil. (Aim for a ratio of two to three drops of tea tree oil to 15 to 20 drops of carrier oil.) “For nail fungus, use a stronger concentration of tea tree oil than you would on the skin of your face,” says Holman.

Tea tree oil may also promote a healthy scalp. “It’s a great ingredient for clarifying hair, so it’s helpful for conditions like seborrheic dermatitis (a variation of dandruff) and scalp folliculitis, as well as general itchiness of the scalp,” says Holman. (“Clarifying” means that a product can help remove product buildup and oil from the scalp.) Look for tea tree–based shampoos or scalp treatments and use these two or three times per week, she recommends. When included in the formula of antidandruff products, research suggests that tea tree oil’s antimicrobial properties may be effective in keeping flakes at bay.

The main side effect to watch for when using tea tree oil is irritation. “Up to 4 percent of people can be allergic [to tea tree oil],” Hooper says. It’s always a good idea to do a patch test before you start treating an area with tea tree. And yet you still may find that your skin reacts negatively to the ingredient later on. If you are allergic to it, “tea tree will irritate your skin within the first two to three weeks, and then the product will irritate your skin each time you use it thereafter,” she says. That skin irritation indicates that you are allergic to tea tree oil, and you should stop using it entirely.

Tea Tree Oil and Skin Conditions

If you have eczema, avoid using tea tree oil. Though tea tree oil may be effective for scalp psoriasis, it has not been proved to treat that skin condition. Finally, while there is evidence from a double-blind controlled clinical trial that tea tree oil gel, when combined with a medication called permethrin, is effective and safe for treating rosacea compared with a placebo, you should not self-treat, as tea tree oil can worsen rosacea symptoms.

• Along with routine dermatologist-guided care, tea tree oil may help treat mild acne and other skin issues, thanks to its antibacterial and anti-inflammatory properties.

• It might take a few months to see noticeable improvements.

• Perform a patch test before using tea tree oil on your skin, and monitor for any irritation or allergic reactions.

• Always properly dilute pure essential oil before using it, or use a product that contains tea tree oil but is formulated for skin.

• Avoid sun exposure, or use quality sunblock after application.