Tea tree oil has potent anti-inflammatory, antimicrobial, and antifungal properties. It may help with acne, toenail infections, athlete’s foot, and more. However, it can irritate the skin and must not be ingested. Read more below to learn the additional health benefits, side effects, and dosage of tea tree oil.
Tea tree oil is derived mostly from Melaleuca alternifolia, a plant native to Australia. For nearly 100 years, tea tree oil has been used in Australia to naturally heal common ailments. It was primarily used for its antimicrobial properties, to cure sore throats, and treat minor injuries .
Now, this oil is commercially available throughout Australia, Europe, and North America and is commonly the active antimicrobial ingredient in many topical treatments .
Three types of aromatic hydrocarbons make up tea tree oil :
Other major constituents of tea tree oil include :
Because tea tree oil can be produced with varying levels of each constituent, mass productions are monitored to keep within international regulations .
Tea tree oil alters the permeability of Candida albicans and other fungal cells. The oil increased the lipid (fat) membrane’s resistance to deformation, inhibited breathing, and stopped the formation of spore outgrowths (germ tubes) [4, 5, 6].
All of the components of tea tree oil except β-myrcene exhibit antifungal properties .
Scientists tested tea tree oil against the fungi Botrytis cinerea and Penicillium expansum. The tea tree oil treatment lowered the total fat content in the membranes of both species. Tea tree oil reduced energy production in both pathogens, though more severely in Botrytis cinerea .
Athlete’s foot is an infection caused by different types of fungus, found on the feet. Both 25% and 50% tea tree oil caused a marked clinical improvement in 158 patients with this condition .
Topical application of 100% tea tree oil (2x daily for 6 months) cured about 18% of 117 patients with toenail infections (onychomycosis). It can also improve nail appearance and symptoms in about 56-60% of patients. The effects were comparable to those of clotrimazole 1% solution .
Dandruff is a fungal skin condition that causes itchy, red patches. One study tested the tolerability of 5% tea tree oil in treating dandruff on 126 patients with mild to moderate dandruff. There was a 41% improvement in dandruff severity compared to the control group .
In a human study of 27 subjects, tea tree oil applied to the skin significantly reduced swelling .
In mice, tea tree oil and terpinen-4-ol reduced swelling .
White blood cells from 7 healthy human volunteers were incubated with tea tree oil to determine its effects on the production of reactive oxygen species (signaling molecules for inflammation) with or without cell stimulation .
The antimicrobial properties of tea tree oil are well known.
Incorporating tea tree oil in a hand wash formula can decrease the spread of pathogens. In a study of 13 participants, a product containing 5% tea tree oil and water and a product containing 5% tea tree oil and 10% alcohol killed pathogens better than a non-medicated soft-soap [16, 17].
With increasing concentrations of tea tree oil, the rate of cell killing and the duration of growth increased. Tea tree oil deteriorates the cell membrane, causing organelle damage and less cytoplasm (cellular fluid), leading to complete cell death in multiple species of microbes .
Another cell study tested the effects of tea tree oil on cell growth and two secreted proteins of Listeria monocytogenes. There was a decrease in cell growth as well as protein secretion .
The antibacterial properties of the oil come from its organic structure and fat-soluble abilities. Together, these allow the tea tree oil to compromise the bacterial membrane. It increases bacteria permeability to allow active compounds inside without disintegrating the membrane itself .
Treatment of Staphylococcus aureus with tea tree oil caused the leakage of potassium ions and constrained breathing. It reduced the bacterial cells’ tolerance to sodium chloride and damaged their biological structures [12, 21, 22, 23].
Similarly, in E. coli, tea tree oil caused detrimental effects on potassium levels, breathing, and structure. However, in contrast to Staphylococcus aureus, E. coli’s cell walls disintegrated [21, 24].
In a study of 124 patients with acne, 5% tea tree oil significantly reduced the number of lesions. The tea tree oil group showed significantly less scaling, itching, and dryness compared with the control treatment. That said, they also reported a longer time to see results .
In 60 patients with mild to moderate acne, applying a 5% tea tree oil gel for 20 minutes (twice daily for 45 days) decreases acne lesions, pustules, and other skin changes much more efficiently than placebo .
No valid clinical evidence supports the use of tea tree oil for any of the conditions in this section. Below is a summary of up-to-date animal studies, cell-based research, or low-quality clinical trials which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.
In a study of 16 gingivitis patients, tea tree oil showed the most improvement in gingivitis and mouth bleeding, out of four mouthwash types. However, it was the least effective in the control of bacterial plaque .
One cell study investigated the antibacterial effects of various essential oils (including tea tree oil) on five types of oral bacteria. 30 seconds of tea tree oil exposure killed bacterial strains completely. It showed significant inhibiting activity against gingivalis, a bacteria found in 85% of chronic gum disease patients that causes inflammation [27, 30].
No clinical evidence supports the use of tea tree oil for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
Scientists incubated herpes simplex viruses with various concentrations of tea tree oil and then used these viruses to infect cells. Tea tree oil prevents the formation of viral cell structures (plaque) within cell cultures [12, 31].
Tea tree oil also stopped the growth of tobacco mosaic virus in plants .
Although tea tree oil can act against viruses with or without an outer coating, the range of tested viruses is limited .
This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.
Though uncommon, skin irritation and allergic reactions to tea tree oil may occur. The reaction may vary from mild to severe and are usually caused by oxidation (breakdown) of the product [32, 33, 28].
You can dilute tea tree oil for safe treatments. However, each person reacts differently to the concentration of the oils, so be cautious when using the oil. Common concentrations used for ailments are:
- Oral/ Mouthwash – 1-5% 
- Dandruff Shampoo – 5% 
- Acne Treatment – 5% 
- Toe Fungus Treatment – 100% 
Aromatherapy involves inhaling the essential oils of plants in order to produce physical and psychological effects. However, clinical studies have yet to examine the aromatherapeutic effects of tea tree oil .
The composition of the tea tree oil is subject to change in environments with exposure to air, moisture, light, and heat. The quality of the oil deteriorates as some chemical compound levels increase and decrease with exposure. To avoid complications, tea tree oil should be stored in dark, dry, and cool places .
The opinions expressed in this section are solely from the users who may or may not have a medical background. SelfHacked does not endorse any specific product, service, or treatment. Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice because of something you have read on SelfHacked.
Many users praise tea tree oil for its antimicrobial and disinfecting properties. They’ve successfully used it for oral hygiene, fungal infections, air purification, and more.
Negative experiences include weird smell and skin irritation caused by undiluted products.