Lemon Myrtle (Backhousia citriodora)
What Is Lemon Myrtle?
Lemon Myrtle is the common name for Backhousia citriodora, a plant of the Myrtaceae family, native to the rainforests of eastern Australia. The material in circulation is leaf — leafy growth taken above ground. Most people search for it simply as Lemon Myrtle; suppliers, pharmacopoeias and interaction databases list it as Backhousia citriodora, and matching the two is the first step in identifying what is actually in a product. Its character is described as intense clean lemon — brighter and sweeter than lemongrass, which is often how the raw material is checked for quality.
Lemon Myrtle entered the reference literature through use rather than through chemistry. Older sources are concerned with where it grows, when it is gathered and how it is prepared, questions that still shape the material on sale today. Beyond its practical use it carries cultural associations — bush herb of brightness and clearing.
Today most searches for Lemon Myrtle come from people reading about colds & flu, antibacterial, antifungal and focus, or checking how it sits alongside a medication they already take. The use most often documented in the literature is up to 98% citral — the highest natural concentration known, followed by strong antimicrobial and antifungal activity documented.
How Does Lemon Myrtle Work?
Lemon Myrtle works as a mixture rather than a single isolated compound, and its profile is usually described by the class of constituents present in leaf rather than by one marker molecule.
Traditional practice described Lemon Myrtle in terms of taste, warmth and preparation rather than molecules — a working vocabulary that predicted which extractions were worth making long before any compound was isolated.
The research base is developing: there are human trials, though sample sizes and designs vary, and this profile cites 1 source. Reported findings centre on leaf oil is 90–98% citral (geranial plus neral); a paediatric trial found 10% lemon myrtle oil resolved molluscum lesions in most treated children. Where research exists, it examines up to 98% citral — the highest natural concentration known, strong antimicrobial and antifungal activity documented and Traditional Aboriginal use for colds and as a food flavouring. These are areas of study, not established outcomes, and results differ by preparation and dose.
How the plant is prepared changes what you actually get. Its constituents move readily into water, fixed oil and glycerin — so a preparation made in another medium will not carry the same fraction of the plant, which is why traditional recipes specify one over another.
The reason Lemon Myrtle is treated as its own entry rather than a substitute for a related plant is proportion: related species share several of these compound classes, but not in the same ratio or concentration.
Because these constituents are processed by the same pathways that handle many medicines, Lemon Myrtle is documented as interacting with topical medications. That is a question of shared metabolism rather than of potency, and it is the main reason the plant is listed in interaction references at all.
Dose, plant part and growing conditions all shift the constituent profile, so two products carrying the name Lemon Myrtle can differ substantially; this is why reference entries specify leaf and, where they exist, standardisation markers.