To dilute tea tree oil, mix 1 to 2 drops into 12 drops of a carrier oil like jojoba, almond, or coconut oil. This produces roughly a 2% concentration, which is the standard strength for most everyday skin applications. Never apply tea tree oil directly to your skin without diluting it first, as the undiluted oil can cause irritation, rashes, and allergic reactions.
Dilution Ratios by Use
The right concentration depends on what you’re using it for. A simple way to think about it: the more sensitive the area, the lower the concentration you need.
- General skin use (1 to 2%): 1 to 2 drops of tea tree oil per 12 drops of carrier oil. This works for minor blemishes, small cuts, and general skincare.
- Acne treatment (5%): About 3 drops of tea tree oil per teaspoon (roughly 5 mL) of carrier oil. A clinical trial of 124 patients found that a 5% tea tree oil gel reduced both inflamed and non-inflamed acne lesions at rates comparable to 5% benzoyl peroxide, with fewer side effects. The tradeoff: tea tree oil works more slowly.
- Scalp treatments (5%): 5 drops per teaspoon of carrier oil, or look for a shampoo that already contains 5% tea tree oil.
- As a toner or spray: 3 drops of tea tree oil into 2 ounces of witch hazel. This creates a very mild solution suitable for wiping across the face.
How to Measure Accurately
Essential oil dropper bottles aren’t precision instruments. Drop sizes vary depending on the bottle’s opening, the oil’s viscosity, and the angle you hold it at. The standard assumption used by aromatherapists is that 30 drops of essential oil equals roughly 1 milliliter. That means each drop is about 0.03 mL.
For home blending, you don’t need laboratory precision. Count your drops carefully and keep your ratios consistent. If you’re mixing a larger batch (say, for a body oil), a helpful rule of thumb: 1% dilution equals about 6 drops of essential oil per ounce (30 mL) of carrier oil. For 2%, double that to 12 drops per ounce. For 5%, use 30 drops per ounce.
Choosing a Carrier Oil
A carrier oil is any neutral, skin-safe oil that “carries” the essential oil onto your skin while buffering its intensity. The best one for you depends on where you’re applying it and your skin type.
For your face, especially if you’re prone to breakouts, choose a carrier oil with a low comedogenic rating, meaning it’s unlikely to clog pores. Sunflower oil, fractionated coconut oil, and jojoba oil are good options. Regular (virgin) coconut oil is thicker and better suited for body use on dry, rough, or scaly skin rather than the face. Sweet almond oil works well for dry or sensitive skin on both the face and body. Avocado oil is rich and moisturizing but heavier, making it a better fit for very dry skin or body applications.
How to Do a Patch Test
Even properly diluted tea tree oil can cause reactions in some people, so test it before committing to regular use. The American Academy of Dermatology Association recommends this approach: apply a small amount of your diluted mixture to the inner forearm or the bend of your elbow, covering an area about the size of a quarter. Apply it twice daily for 7 to 10 days. If you see no redness, itching, or irritation in that time, you can start using it on the intended area.
If you’re planning to use it on your face, test behind your ear at the jawline instead. That skin is closer in sensitivity to facial skin and gives you a more reliable preview of how you’ll react.
Where Not to Use It
Tea tree oil should never be swallowed. Ingesting it can cause serious toxicity, including confusion, difficulty breathing, loss of muscle control, and in severe cases, coma. Keep it away from children and pets.
It should also never be applied to mucous membranes, including inside the nose, mouth, ears, or eyes. Eye exposure can cause corneal injury. If you have eczema or very sensitive skin, avoid tea tree oil entirely, as it’s likely to worsen irritation rather than help.
Storage and Shelf Life
Tea tree oil degrades when exposed to light, heat, air, and moisture. As it oxidizes, its chemical composition shifts significantly. The compounds that give fresh oil its beneficial properties break down, and oxidation byproducts form that are more likely to trigger allergic reactions. Research published in Clinical Microbiology Reviews found that the most definitive evidence points to these oxidation byproducts as the primary cause of allergic skin reactions to tea tree oil.
Store your tea tree oil in a dark glass bottle, in a cool place, with the cap tightly sealed. If your oil smells different than when you bought it, looks cloudy, or has been open for more than a year or two, replace it. Old oil is both less effective and more likely to irritate your skin.