Ingredient Beauty BenefitsOther · Melaleuca Alternifolia Leaf Oil
Tea tree oil: it beat placebo in 60 people, but that is one 45-day trial
In a double-blind trial of 60 people using a 5% gel for 45 days, total lesion count and acne severity improved significantly more than with placebo — 3.55 and 5.75 times more, respectively. It is one trial, and 45 days is short.
Last checked Sep 16, 2026
Start here
- What it is
An essential oil distilled from the leaves of the Australian tea tree. It is a mixture of dozens of components.
- What it is used for
Products marketed for acne.
- How it is said to work
Terpinen-4-ol and others in it are said to disrupt bacterial cell membranes. Essential oils are also a common cause of contact dermatitis, more so once oxidised in air.
There are no numbers and no citations in this box. What has been established, and how far, is below.
At a glance
- In pregnancy
- Not established
- Irritation
- Moderate
- Daytime use
- ✓ Fine
- How well established
- Moderate evidence
- Concentration studied
- 5%
- Length of the studies
- 6 weeks
Not a measurement — reported irritation grouped into five steps. It varies between people.
“Concentration studied” and “Length of the studies” are taken straight from the research on this page. They are not a recommended dose, and the figure for each finding is written out in the text.
This is not how large the effect is but how well confirmed it is. It shows the highest grade among the findings on this page.
Tea tree oil is the essential oil of Melaleuca alternifolia, native to Australia. It is one of the few plant extracts with an actual vehicle-controlled trial in acne.
Essential oils are also fragrance materials, which is why contact allergy follows this ingredient wherever its evidence goes.
What is established
The same ingredient at a different strength, in a different formula, is a different product. These are the conditions the studies used.
Lesion counts fell further than with placebo — 60 people, 45 days
Sixty patients with mild to moderate acne were randomised to tea tree oil gel (n = 30) or placebo (n = 30) in a double-blind trial, followed every 15 days over 45 days.
Both total lesion count (TLC) and acne severity index (ASI) improved significantly more with tea tree oil. The degree of improvement was 3.55 times for TLC and 5.75 times for ASI relative to placebo.
Two qualifications. It is one trial, and 45 days is short for an acne study. The comparator being placebo is a strength of the design, but it was not compared against other acne treatments.
- Randomised controlled trial in people · 60 participants · 6 weeks · Compared with vehicle (same formula minus the active) · Funding not declared · Endpoint clinical events (cancers, lesion counts) PMID 17314442 · abstract read
How to use it
- The trial used a 5% gel. Applying undiluted oil is a different proposition and irritates badly.
- Spot application is the safer route. The wider the area, the higher the irritation and allergy risk.
- Do not layer it with retinol on the same night.
Cautions
- Contact allergy is reported with this ingredient, particularly with oxidised oil. Do not use old product.
- Essential oils are fragrance. If your skin reacts to fragrance, this is one to avoid.
- Acne is a medical condition. With significant inflammatory acne, seeing a clinician is faster.
- We found no established data on use during pregnancy.
With a new ingredient, apply a small amount somewhere inconspicuous, such as the inner arm, for two days first. Stop if it reddens or stings.
Related skin concerns
What this article relies on
Unless marked otherwise, a paper was read to the abstract. Only papers whose full text we opened are marked as such.
- PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16