Evidence Based

6 Interesting Health Benefits of Tea Tree Oil + Side Effects

Written by Helen Quach, BS (Biochemistry) | Last updated:

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pain and inflammation
Tea tree oil has many health benefits including anti-inflammatory, antimicrobial, and antifungal properties. Read more below to learn about the additional health benefits and risks of this medicinal plant.

What is 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 anti-microbial properties, to cure sore throats, and to treat minor injuries [1].

Now, this oil is commercially available throughout Australia, Europe, and North America and is commonly the active antimicrobial ingredient in many topical treatments [1].

Constituents of Tea Tree Oil

Three types of aromatic hydrocarbons make up tea tree oil:

  • Terpinen-4-ol
  • Terpinolene
  • 1,8-cineole

Other major constituents of tea tree oil include [2]:

  • Γ-terpinene
  • α-terpinene
  • α-terpineol
  • p-cymene
  • α-pinene

Because tea tree oil can be produced with varying levels of each constituent, mass productions are monitored to keep within international regulations [3].

Health Benefits of Tea Tree Oil

1) Tea Tree Oil is Anti Inflammatory

Terpinen-4-ol, a component of tea tree oil, prevents the production of inflammatory compounds (TNF, IL-1β, IL-8, IL-10, and prostaglandin E2) [4].

In mice, scientists applied tea tree oil and terpinen-4-ol to their skin after injecting the mice with a compound to induce swelling. Tea tree oil reduced swelling [5].

In a human study, scientists injected 27 subjects with histamine diphosphate (inflammation inducing drug) then treated them with 100% tea tree oil or paraffin oil. The tea tree oil did not decrease the mean size of the inflicted area however it significantly decreased the amount of swelling. Paraffin oil had no significant effect on swelling and size [6].

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 [7].

Tea tree oil directly stimulated the production of reactive oxygen species by granulocytes and monocytes (types of white blood cells). For each stimulating agent used, tea tree oil decreased the production by granulocytes and monocytes, more so with granulocytes [7].

2) Tea Tree Oil Is Antibacterial

The antimicrobial properties of tea tree oil are most well known. Its microbial activity has been effective against species including Propionibacterium acnes and Staphylococcus aureus [8].

A cell study tested the antimicrobial properties of tea tree oil on two strains of bacteria (Escherichia coli and Staphylococcus aureus) and fungi (Candida albicans and Aspergillus niger) [9].

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 all species except Aspergillus niger [9].

Another cell study utilized Listeria monocytogenes, a bacteria that causes Listeriosis, to test 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 [10].

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 [11, 12].

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 [13].

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 [4, 14, 15, 16].

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 [14, 17].

Tea Tree Oil For Biomedical Applications

In a cell study, a sample of biphasic calcium phosphate – PVDF polymer film (bone substitute biomaterial made from non-reactive plastic) with E. coli and S. aureus were treated with eucalyptus and tea tree oil. This resulted in the leakage of vital fluids from the microorganisms. Cell death was observed in bacterial cells [18, 19].

3) Tea Tree Oil is Antifungal

Similar to results found for bacteria, tea tree oil also altered the permeability of C. albicans cells. The oil increased the lipid (fat) membrane’s resistance to deformation, inhibited breathing, and stopped the formation of spore outgrowths (germ tubes) [20, 21, 22].

Once the scientists removed the tea tree oil, the fungal cells were still able to form a germ tube. However, there was a delay, indicating a residual effect [21, 22].

All of the components of tea tree oil except β-myrcene exhibit antifungal properties [23].

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 [24].

Tea Tree Oil Treats Dandruff

Dandruff is a fungal skin condition that causes itchy, red patches. A single-blind parallel group study tested the tolerability of 5% tea tree oil in treating dandruff on 126 patients with mild to moderate dandruff [25].

There was a 41% improvement in dandruff severity compared to the control group [25].

Tea Tree Oil Treats Athlete’s Foot

Athlete’s foot is a form of ringworm, an infection caused by different types of fungus, found on the feet. Tea tree oil inhibited the growth of fungus and bacteria on the body in various studies [26, 27].

4) Tea Tree Oil May Be Anti Viral

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 [4, 28].

Tea tree oil also stopped the growth of tobacco mosaic virus in plants [4].

Although tea tree oil can act against viruses with or without an outer coating, the range of tested viruses is limited [4].

5) Tea Tree Oil Helps Improve Oral Hygiene

You can use tea tree oil as a mouthwash to decrease the number of bacteria and treat gingivitis. The oil reduces the levels of compounds associated with bad breath [29, 30, 31].

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 [29, 32].

In a study (DB-RCT), 16 gingivitis patients used one of four types of mouthwash. Tea tree oil showed the most improvement in gingivitis and mouth bleeding. However, it was the least effective in the control of bacterial plaque [30].

In a cell study of cavities from extracted teeth, scientists tried to determine the effectiveness of natural products in-vitro and to use these in mouthwashes and teeth cleaners [31].

6) Tea Tree Oil Treats Acne

Tea tree oil can reduce inflammation that occurs with acne.

In a study (SB-RCT), researchers assessed the effectiveness of 5% tea tree oil for treating acne by comparing it to 5% benzoyl peroxide While both treatments significantly reduced the numbers of lesions, the tea tree oil group showed significantly less scaling, itching, and dryness. The tea tree oil group reported longer times to see results and fewer side effects [33].


There are few clinical trials on tea tree oil’s effects. Existing clinical trials have small sample sizes and other limitations including the specificity of the questions answered limited trials, and misleading data. Therefore, you should be cautious when using tea tree oil for its purported health benefits.

Risks/Side Effects

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 [34, 35, 30].

Tea tree oil is toxic when ingested but is safe to inhale or apply topically. Tea tree oil is hazardous to pets as well. No known human deaths have occurred because of tea tree oil [34, 35, 30].


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% [30]
  • Dandruff Shampoo – 5% [25]
  • Acne Treatment – 5% [36]
  • Toe Fungus Treatment – 100% [37]

Tea Tree Oil for Aromatherapy

Aromatherapy involves inhaling the essential oils of plants in order to produce physical and psychological effects. However, clinical studies have yet to conclude the aromatherapeutic effects of tea tree oil [38].

Proper Storage

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 [4].

User Reviews

“First, I love this tea tree oil! The smell is very pungent, but a good pungent smell. I would compare it to a strong minty scent. It’s great for hot oil treatments for hair/scalp, it’s great with blending along with other oils.”

“It’s too irritating for my sensitive skin and the smell is awful.”

“I use tea tree oil in an oil lamp when I have a cold. It worked very well with helping me breathe better.”

“Having tea tree oil in every first aid kit and household would be a good thing. I have used this to treat many skin issues, yeast issues, wounds, cuts and as a mouthwash according to directions. Best to dilute as this is powerful stuff. I like this brand. Price is good. Always follow directions.”

“I been using this for a while, it takes a while to work and has an extreme weird scent, and very little but useful.”

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About the Author

Helen Quach

BS (Biochemistry)

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