Tea tree oil
Diluted tea tree oil has modest support for mild to moderate acne: a 2026 meta-analysis of 7 studies found a reduction in severity, and in a 1990 trial 5% gel was slower than 5% benzoyl peroxide but caused fewer side effects. A 5% shampoo also cut dandruff in one trial, while evidence for nail fungus and head lice is weak.
Never swallow it, and never use it neat on skin: it is poisonous if eaten and a known cause of contact allergy, more so when the oil is old or oxidised.
At a glance
Last reviewed 10 October 2026What it's used for
Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.
| Use | Evidence | What the research shows |
|---|---|---|
| Mild to moderate acneCompare remedies for skin → | Moderate | A 2026 meta-analysis of 7 studies (445 people) found tea tree oil was associated with lower acne severity than controls (pooled odds ratio 0.74, 95% CI 0.63 to 0.88), with mostly mild local side effects. In the trial most often cited, 124 people used 5% tea tree oil gel or 5% benzoyl peroxide lotion: both cut inflamed and non-inflamed spots, benzoyl peroxide acted faster, and tea tree oil had fewer side effects. An earlier systematic review of randomised trials said more evidence was needed, and studies were small and short.3,2,4 |
| DandruffCompare remedies for hair & nails → | Limited | In 126 people with mild to moderate dandruff, a 5% tea tree oil shampoo used daily for 4 weeks improved the severity score by 41% against 11% for placebo shampoo, with no adverse effects reported. It was a single-blind trial, and we found no second trial to confirm it. The scaliness rating improved but not significantly.1 |
| Fungal toenail infection (onychomycosis) | Limited | In 117 people with culture-proven toenail infection, 100% tea tree oil twice daily for 6 months matched 1% clotrimazole solution: culture cure was 18% against 11%, and 60% against 61% had partial or full clinical improvement. Both were weak treatments, since most infections were not cleared. NCCIH says the amount and quality of research is not enough to reach any conclusion.5,8 |
| Head lice | Limited | In 123 people, a product containing tea tree oil plus lavender oil left 97.6% louse-free after three weekly applications, against 25% with a pyrethrin product. It was a combination product, so the result cannot be credited to tea tree oil alone, and NCCIH notes that it has only been tested with other ingredients. Plain tea tree oil for lice is untested by any trial we read.6,8 |
| Skin generally (wounds, eczema, fungal skin infection) | Traditional | The National Capital Poison Center says there is very little scientific evidence that tea tree oil works for most skin conditions. The 2023 systematic review of 46 randomised trials called the quality of research poor to modest, and said any local anti-inflammatory effect on skin needs more research.9,4 |
How much
Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.
How people take it
Safety
Who should avoid
- Swallowing it — poisonous; children have become confused, unsteady or unconscious
- Children — keep out of reach and locked away; poison centres warn about ingestion
- Old or oxidised oil — more likely to irritate and cause contact allergy
- Undiluted oil on skin or in strengths of 25% or more — more side effects in trials
- Known contact allergy to essential oils or turpentine — reactions often overlap
Known interactions
Questions people ask
Is tea tree oil good for hair and dandruff?
A 5% tea tree oil shampoo used daily for 4 weeks reduced dandruff severity by 41% against 11% for placebo in one trial of 126 people. It is a single trial, so the evidence is limited. We found no trial showing it helps hair growth or hair loss.
Does tea tree oil work for acne on the face?
It appears to help mild to moderate acne a little. A 2026 meta-analysis of 7 studies found lower acne severity, and 5% gel worked more slowly than 5% benzoyl peroxide but caused fewer side effects. Use a diluted product, not the neat oil, and patch-test first.
What are the side effects of tea tree oil?
On skin, redness, dryness and itching are the usual effects, and contact allergy is well documented, with positive patch tests in 0.1% to 3.5% of people tested. Oxidised oil is more allergenic. Swallowing it is dangerous: NCCIH lists confusion, unsteadiness, inability to walk and coma.
Can tea tree oil treat nail fungus or head lice?
Not reliably. In one trial 100% oil matched clotrimazole for toenail fungus, but both cleared few infections. For head lice, only a tea tree and lavender oil combination has been tested, and NCCIH says the effect cannot be credited to tea tree oil alone.
Sources (9)
- Randomised trial Satchell AC, Saurajen A, Bell C, Barnetson RS. Treatment of dandruff with 5% tea tree oil shampoo. J Am Acad Dermatol. 2002.
- Randomised trial Bassett IB, Pannowitz DL, Barnetson RS. A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne. Med J Aust. 1990.
- Meta-analysis Ye Y, Lim JJ, Huang Z, Chew FT. Efficacy and Safety of Melaleuca alternifolia (Tea Tree) Oil for Acne-A Systematic Review and Meta-Analysis. Phytother Res. 2026.
- Systematic review Kairey L, Agnew T, Bowles EJ, Barkla BJ, Wardle J, Lauche R. Efficacy and safety of Melaleuca alternifolia (tea tree) oil for human health-A systematic review of randomized controlled trials. Front Pharmacol. 2023.
- Randomised trial Buck DS, Nidorf DM, Addino JG. Comparison of two topical preparations for the treatment of onychomycosis: Melaleuca alternifolia (tea tree) oil and clotrimazole. J Fam Pract. 1994.
- Randomised trial Barker SC, Altman PM. A randomised, assessor blind, parallel group comparative efficacy trial of three products for the treatment of head lice in children--melaleuca oil and lavender oil, pyrethrins and piperonyl butoxide, and a suffocation product. BMC Dermatol. 2010.
- Review de Groot AC, Schmidt E. Tea tree oil: contact allergy and chemical composition. Contact Dermatitis. 2016.
- Regulator/health agency National Center for Complementary and Integrative Health. Tea Tree Oil.
- Poison centre National Capital Poison Center. Tea tree oil: Remedy and poison.
Last reviewed 10 October 2026 · Next review April 2027 · How we rate evidence
Reader notes
Experiences and questions from readers, read by an editor before they appear. They are personal accounts, not evidence, and are not medical advice.