Traditional plant-based medicines have been used as remedies for various ailments and conditions by many cultures worldwide. These natural remedies — among which lemon myrtle oil holds a high ground — were the cornerstone of healing long before modern pharmaceuticals. Lemon myrtle, scientifically known as Backhousia citriodora, is a long-standing medicine.
Lemon myrtle is a native Australian plant known to many for its citrus aroma and use to season food. However, it has traditionally been used for its therapeutic properties for centuries. Revered by Indigenous Australians for generations, lemon myrtle oil is now finding its way into modern wound care. Scientists hope to combine ancient wisdom with scientific evidence to validate the efficacy of this remedy.
This article explores the botanical origins of lemon myrtle and how Aboriginal communities have used it to treat wounds and infections. We will also explore how researchers have found evidence validating its antimicrobial and healing potential, breaking down the compounds responsible for these effects. Lastly, we will compare its efficacy against modern remedies and offer practical guidance on using lemon myrtle oil safely.
Botanical description and origin
Backhousia citriodora, commonly known as lemon myrtle, is a medium-sized shrub that grows up to about 8 meters. However, it can reach up to 20 meters in the wild. It belongs to the family Myrtaceae. Plants in this family include eucalyptus and tea trees, which are generally known for their aromatic fragrance. Lemon myrtle has glossy green leaves with a strong lemon fragrance when crushed. The species name citriodora aptly describes the lemon scent that the leaves emit.
On the other hand, the genus Backhousia was given in honor of English botanist James Backhouse. Ferdinand von Mueller first scientifically described this species in 1845. Other names, such as lemon-scented ironwood, sweet verbena tree, sand verbena myrtle, and tree verbena, are also known as lemon myrtle.
Lemon myrtle is native to the subtropical forest of central and southeastern Queensland, Australia. It thrives in wetter coastal regions, well-drained soils, and sheltered waterways 50 to 800 meters above sea level. The Backhousia genus is mainly found in the coastal rainforest areas of Queensland and Northern New South Wales. Still, it can withstand various conditions, from full sun to partial shade. However, in cooler climates, it won’t grow as large as in the tropics, and it is sensitive to frost, especially when young.
During autumn or early summer, the plant produces a cluster of exquisite, lemon-scented white flowers. Over time, these beautiful flowers become nut-like capsules with several tiny seeds. The Backhousia citriodora has two groups with different chemical compositions. The first one is the citral chemotype, which is widely cultivated for its flavoring and essential oil. This group has the highest level of citral, the active ingredient, of any plant tested. The other group is the citronella chemotype, which isn’t as common and has traditionally been used for its insect-repellent properties.
Traditional uses of lemon myrtle among Indigenous Australians
Indigenous Australians have used lemon myrtle, among other plants, for millennia for wound care and healing. They also used it to flavor food or as a component in tea. For instance, they ingeniously wrapped the plant’s leaves in paper to give fish and other dishes the lemon aroma.
Medicinally, the natives crushed the leaves to make an antiseptic paste or poultice, which was directly applied to wounds, cuts, or abrasions. They recognized lemon myrtle’s ability to cleanse wounds, protect against injuries, and prevent infection. Beyond wound care, the plant was also used to treat coughs, colds, and stomach ailments. For example, the crushed leaves could be inhaled to treat headaches or brewed into a medicinal tea.
In some cases, Australian Aboriginals chewed the leaves directly for oral health or to treat minor mouth infections. But what is it in the lemon myrtle that makes it a culinary and medicinal delight?
Chemical composition of lemon myrtle oil
The essential oil of lemon myrtle is obtained from its leaves. Researchers have found several bioactive compounds that give the plant its characteristic scent and therapeutic properties. Citral is the most abundant compound, comprising 90-98 percent of the oil’s composition. This citral concentration is higher than in lemongrass and lemon itself.
That said, the citral compound is not a single molecule. It is a mixture of two isomeric aldehydes: geranial and neral. These two compounds have antimicrobial and antifungal properties, which help prevent infections in wounds or cuts.
Besides citral, lemon myrtle essential oil contains other compounds, including citronellal, linalool, and β-myrcene. These, plus the presence of phenolic compounds, are responsible for the oil’s antioxidant properties. Scientists have also found that the plant has high levels of vitamins A and E, zinc, calcium, and magnesium.
The oil’s composition has also been beneficial for other ailments, such as sinus pain, sore throat, acne, insect bites, insomnia, and more.
Scientific evidence for lemon myrtle’s wound healing properties
Recent scientific research has validated many of the plant’s traditional uses. These studies focused on lemon myrtle’s antimicrobial and anti-inflammatory properties, which are necessary for wound care.
Researchers have confirmed that lemon myrtle has a strong antimicrobial effect on bacteria and fungi. They demonstrated its effectiveness against wound pathogens such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. It even showed effectiveness against antibiotic-resistant strains like MRSA. The essential oil also has a high Rideal-Walker coefficient — a historical measure of disinfectant efficacy.
Beyond its antimicrobial properties, the plant demonstrated anti-inflammatory properties in in vitro studies. It reduces pro-inflammatory mediators such as nitrous oxide (NO) and tumor necrosis factor-alpha (TNF-α). The main compound, citral, plays a role in these anti-inflammatory effects.
Lastly, scientists are also discovering the wound-healing potential of lemon myrtle oil. Researchers from the University of South Queensland have been investigating whether lemon myrtle can be used to create a low-cost hydrogel for wound treatment since 2021. They recently published their findings in Heliyon, showing that the plant had wound-healing properties comparable to those of everyday hydrogel-based wound dressings on the market.
“This could be effective in speeding up the wound healing process, as well as maintaining that wound microenvironment, actually to help the normal healing process too,” Dr. Danuki Seneviratne, one of the lead researchers, said in an interview with ABC.
Lemon myrtle comparison with other wound treatments
Lemon myrtle is a better traditional wound remedy than honey or aloe vera. In Australia, it has frequently been compared to tea tree oil, another essential oil that native Australians use for its antimicrobial properties.
Several studies have shown that lemon myrtle oil is more potent against bacteria and fungi than tea tree oil. Notably, it had a higher coefficient in the Rideal-Walker test, suggesting more effectiveness in stopping microbial growth. Still, both oils are valued for their ability to treat wounds, skin infections, and minor cuts.
The plant also holds more water than modern wound treatments. The study mentioned above showed similar physicochemical properties to commercially available wound dressings. It shows that lemon myrtle can be a low-cost alternative to hydrogel wound care products. The essential oil can also become an effective alternative for people who experience adverse side effects or resistance to synthetic antibiotics and antiseptics.
How to safely use lemon myrtle essential oil for topical applications
Essential oils can be potent, so it’s recommended to use caution when applying lemon myrtle oil topically. The high citral concentration can cause skin irritation when used undiluted, so it’s best to add a carrier oil before applying. Experts advise diluting the oil to a concentration of 0.7 to 1 percent. You should add only three drops of lemon myrtle oil to 30 ml of carrier oil, such as coconut oil.
However, in one study, a concentration of 10 percent was moderately effective in reducing the skin lesions caused by molluscum contagiosum. Remember, while a higher concentration may be effective under specific conditions, always seek professional guidance before using it. Also, you should perform a patch test on a small area before using it on a larger part of your skin. Be careful when using myrtle oil on sensitive skin or in children under 2 years old.
For dilution before topical application, you can use several carrier oils such as jojoba, coconut, almond, or olive oil. However, great caution should be taken for oral use, especially among pregnant and breastfeeding women, diabetics, infants, and young kids. Also, always seek professional advice before using it for any internal use.
Availability of lemon myrtle oil wound healing products
With the growing scientific validation of lemon myrtle essential oil, its wound care products have become available on the market. You can find these products in balms, lotions, pure essential oils, soaps, and sprays in Australia and around the world.
University of Southern Queensland researchers have also developed a cheaper antimicrobial hydrogel that has the potential to heal chronic wounds. Current wound dressings can cost hundreds of dollars, but lemon myrtle hydrogel can be produced for around $30. So they see potential relief for low-income patients with chronic wounds.
Culinary uses: Lemon myrtle in cooking and tea
Beyond its healing properties, lemon myrtle has become a popular Australian culinary herb due to its lemony flavor, which often surpasses that of actual lemons or lemongrass. You can use lemon myrtle leaves to enhance sweet and savory dishes with a zesty fragrance and tang. Another advantage over lemon juice is that lemon myrtle oil does not curdle dairy. So, it’s a favorite of chefs because it maintains that flavor without altering the texture of cream-based sauces and desserts, such as cheesecakes, lemon-flavored sorbets, and creamy soups.
Another common use is as an ingredient in herbal tea. Lemon myrtle tea is taken to ease sore throats, indigestion, and mild respiratory issues. It is also caffeine-free, making it a great evening drink that can be enjoyed on its own or combined with other ingredients like ginger, peppermint, or chamomile.
Conclusion: Blending traditional wisdom with modern science
Lemon myrtle (Backhousia citriodora) stands out as a remarkable Australian native plant, and that’s why it’s regarded as the “Queen of Australian herbs”. It has a rich history of traditional use among Indigenous Australians, and the growing body of science blends time-honored wisdom with modern knowledge. The high citral content of lemon myrtle essential oil is the main factor behind its potent antimicrobial and antiseptic properties, surpassing other renowned natural antiseptic oils like tea tree oil.
This plant presents an appealing alternative to people who dread a trip to the pharmacy, those who have developed antibiotic resistance, or those who have adverse side effects after using synthetic antibiotics or antiseptics. However, you must use essential oils safely by ensuring proper dilution to reduce the risk of skin inflammation or sensitization. Caution is also recommended for vulnerable individuals like children, pregnant or breastfeeding, or those taking other medications.
Future research should focus on how people can effectively administer wound care products. Is it better if used as a cream, ointment, or dressing? While the current evidence is encouraging, future studies can shape how we approach healing, opening an avenue to traditional knowledge. Whether brewed as tea, infused in culinary dishes, or applied topically through carefully formulated products, lemon myrtle offers more than a pleasant scent; it provides the possibility of low-cost, natural healing.
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