Myrtaceae
Melaleuca alternifolia
Tea tree · Narrow-leaved paperbark
- Part used
- leafoil
- Native range
- A restricted area of northern New South Wales and southern Queensland, in swampy ground
- Morphology
- A small paperbark tree to seven metres with layered papery bark, fine needle-like leaves and creamy bottlebrush flower spikes.
What is in it
Evidence
Genuine antimicrobial activity, with reasonable trial evidence for acne and for tinea, and some evidence in decolonising MRSA. Comparable to benzoyl peroxide for acne with slower onset and less irritation.
Safety
Topical use is generally well tolerated, though contact dermatitis is common and increases as the oil oxidises with age and light exposure. Ingestion is genuinely toxic — ataxia, drowsiness and coma are documented, including in children. Reports of prepubertal gynaecomastia associated with topical tea tree and lavender oils exist and remain contested.
Interactions: Additive skin irritation with other topical actives
Regulatory: Permitted topically; not for internal use. An Australian Standard specifies terpinen-4-ol and cineole content.
Historical use
Used by Bundjalung people of northern New South Wales, whose Country the tree grows on. Commercial distillation began in the 1920s after Arthur Penfold reported its antiseptic activity, and Australian forces carried it in first aid kits during the Second World War.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Tea tree is Australia's most commercially successful medicinal plant and a compact case study in who benefits from one.
It grows naturally in one small area of northern New South Wales, on Bundjalung Country, and its antiseptic use there long predates the industry. Commercial distillation began in the 1920s on the strength of a settler chemist's paper. The industry is now worth a great deal and is Australia's principal essential-oil export.
The oil also demonstrates why an expiry date on an essential oil is not marketing. Terpinen-4-ol oxidises on exposure to air and light into compounds that are considerably more allergenic than the fresh oil. An old bottle is not a weaker product; it is a more irritant one.
Nomenclature verified against GBIF backbone taxonomy.