Emma Hartley
(Adv.DipHSc, DipHSc)
Mānuka has long been used within traditional Māori medicine and has many therapeutic effects including anti-inflammatory and analgesic among many others.
Mānuka can assist with:
- Bacterial and viral conditions
- Upper respiratory infections
as well as having sedation and antifungal properties.
Introduction
Mānuka is a well-known plant within New Zealand. Commonly found growing with Kānuka, both loosely known as “scrub” on farmland.
Furthermore, the wood was used by Māori for a range of uses from fishhooks, spears, clubs and when burnt still green, the smoke was known to force out vermin and lice.
Mānuka is most popularly known for its honey, which has been and continues to be well researched for its health benefits.
Mānuka oil is often confused with tea tree oil, however, while they are similar looking, they are actually very different at the constituent level.
Other names
Botanical name: Leptospermum scoparium.
Family: Myrtaceae.
Māori: Kāhikatoa, Pata.[1]
Other names: New Zealand tea bush, New Zealand tea tree, red tea tree, broom tea tree, (Brazil) árvore-chá, éricafalsa-érica, leptospermo, (Germany) Manukastrauch, RoterSüdsee-Myrte, Besenartige, (South Africa), manuka myrtle, manukamirt, (Sweden) rosenmyrten.
Characteristics
Mānuka is native to New Zealand, is found in both North and South Islands and Stewart Island.
It is a very hardy tree that can grow up to 10 metres tall, with small sharp-tipped leaves. The bark is short, flaky and wispy.[2]
Mānuka plants spread with seeds being released from the capsules, quickly creating dense clusters of bushes. The Mānuka tree provides shelter and shade for other young plants to grow under its protection.[2,3]
The flowers are white and pink with red stamens usually accompanied by little nut-like capsules of a grey colour.
Mānuka thrives in a range of environments such as recently cleared land, all soil types and is tolerant of drought, wind and frost.
Mānuka has long been entitled as a troublesome weed due to its ability to thrive quickly in almost all areas of New Zealand with many efforts over the years to try and eradicate it.
Now, Mānuka plants are being encouraged to thrive as the research continually supports its health benefits.[3]
Mānuka oil is developed by soaking young plant matter inclusive of seeds, then steam distilling to extract the oil.[4] The components differ depending on where the plant material has been harvested. The main constituents presenting in commercially available manuka oil are listed in the following table.
| Component | Content |
| Leptospermone | 0.8-19.4% |
| Calamenene | 2.5-18.5% |
| δ-Cadinene | 0.9-6.9% |
| Cadina-1,4-Diene | 0.1-5.9% |
| Flavesone | 0.7-5.8% |
| Cadina-3,5-Diene | 3.0-10.0% |
| α-Copaene | 4.3-6.5% |
| α-Selinene | 1.3-5.0% |
The active constituents present in mānuka are triterpene acids and their derivatives which are known to have antioxidant, anti-inflammatory and antibacterial effects.
Leptospermone provides insecticide and vermifuge qualities.
Mānuka honey provides the well-documented methylglyoxal (MGO), the primary antimicrobial constituent that disrupts processes such as enzyme function and cell replication in microbes.[5,6]
Along with hydrogen peroxide (present in all honeys), polyphenols and flavonoids and a low pH level, mānuka honey provides an inhospitable environment for microbes to live in.[7]
Use
Captain James Cook gave Mānuka the name of Tea Tree when he encountered it as he made tea from its leaves. However, it is much different from the Tea Tree of Australia (Melaleuca alternifolia), where Tea Tree oil is derived from. Mānuka oil as of recently is becoming more noticeable in its own right.
Traditional use
The Māori have long celebrated, recognised and utilised Mānuka for
- Wound healing
- Internal wellness when brewed into a tea
- Green wood fires for pest control
- Smoke used for post drowning resuscitation
- Skin conditions
- Pain relief
- Inhalation for colds treatment
- Digestion support
- Oral health support.[5]
Medicinal use
Mānuka can assist with:
- Fighting bacterial and viral conditions
- Tumour fighting properties
- Upper respiratory infection support
- Sedation properties
- Antifungal properties.[5]
Mānuka continues being researched for its health benefits, especially mānuka honey.
Health benefits
Extensive research has been conducted on mānuka, specifically mānuka honey. However, mānuka oil is slowly making an entrance due to its own health benefits.
Wound healing
This facet of mānuka’s power is generally focused on mānuka honey. The constituents present in mānuka honey provide an environment that is antimicrobial, anti-inflammatory and keeps the wound moist to allow healing.
The antimicrobial factor sees an environment supportive of tissue regeneration while not promoting proliferation of bacteria, reducing the likelihood of infection.[8]
A 2021 study showed significant results on wound healing in patients with facial wounds. These wounds were struggling to heal and the application of mānuka honey proved scientifically beneficial.[9]
The study has shown the effectiveness of mānuka oil combined with hyperthermia for wound healing and has enhanced the migration of fibroblast cells to the wound site.[10]
Antibacterial activity
Mānuka is proving beneficial and is gathering momentum as a scientifically proven antibacterial agent. The most researched and proven action is against Staphylococcus aureus.
The mechanism of action from mānuka honey is its activity against the cell membrane. MGO works to disrupt the cell membrane which upsets the overall integrity of the bacteria cell.[7]
Furthermore, mānuka honey interferes with biofilm formation. Biofilm protects bacteria from antibiotics by acting as a shield and disrupting adherence of antibiotics to the bacteria, which ensures survival for bacteria cells.[10]
As the following diagrams show, mānuka honey is extremely active against S. aureus.
Manuka honey is extremely active against S. aureus.
Leptospermone and isoleptospermone are β-triketones present in mānuka oil which exhibit antibacterial activity against both Gram-positive and Gram-negative bacteria.
These constituents work against the cell membrane causing cell death. Similarly, they work against methicillin-resistant S. aureus (MRSA), which is a strain resistant to antibiotics.[7]
Mānuka works against multiple other bacteria that cause skin infections and periodontal disease; however, more research is required.[11]
Mānuka oil, leaf extract and root extract have shown to be active against the pathogen E. coli.[12]
Mānuka and viral infection
The flavesones present in mānuka fight viral activity by reducing the size of viral plaques and can inhibit viral replication which decreases the viral load for the host.
Specifically, Herpes simplex virus type 1 or 2 (HSV-1, HSV-2), can be affected by mānuka oil, while both the flavesone and leptospermone show inhibitory factors on the HSV virus.[11]
Mānuka and anti-fungal properties
Mānuka oil has been shown effective against Candida albicans by increasing membrane permeability due to the changes within the cell wall.
Candida causes health problems such as yeast infections and thrush. Both mānuka oil and honey contain the constituents that provide anti-fungal activities.
Mānuka and other health benefits
Mānuka is proving to be a powerhouse of health benefits. Along with antibacterial, antifungal and antiviral properties, mānuka is showing promise within the dental and digestive health.
Excitingly, mānuka has shown a role in the ongoing battle against cancer. Studies have shown inhibitory factors mānuka provides against the spread of breast and liver cancer cells, coupled with the cell membrane disruption it causes, could prove beneficial for use in human cancer treatment.[13]
Therapeutic dosage
Fluid extract (1:2) – 20-60 mls per week.
3 teaspoons of fresh leaves or 2 teaspoons of dried leaves in 1 cup of boiling water (steep for 10-20 minutes), cover to prevent evaporation of volatile oils.[14]
Clinical trials are lacking to determine toxicity level and dosing guidance.[15]
Safety concerns
There have been some adverse effects proposed or suggested but need to be further researched. One possible effect of mānuka oil use both internally and externally is the interference of iron, vitamin and mineral absorption due to the tannins present.
RELATED — Iron (for immunity support and energy production)
This is more likely to occur if the mānuka oil is used over a long period of time. Taking away from meals and increasing vitamin C intake would be advisable.
RELATED — Vitamin C (Immunity and Collagen booster)
Spasmolytic actions have been noticed with mānuka oil use. These actions are contraindicated for use in pregnancy and lactation due to the possibility of inducing labour.
Safety concerns with mānuka honey include allergy to bee products and use in diabetic people due to the sugar content of honey.
Possible interactions with medications
No interactions that are well documented due to limited research about mānuka’s usage.[15]
Bardy (2012), & Hawley (2014) indicated an interaction between L. scoparium and benzodiapene receptors, specifically GABA-A receptor-chloride channel complex, however, these were both in relation to mānuka honey products.[16,17]
Possible interactions with herbs and supplements
No well-documented interactions.
Summary
Note — feel free to share or download this illustration.
Related Questions
1. Are mānuka leaves edible?
Yes, mānuka leaves are ingestible.
They are used to make tea, can be ground down into a powder, or straight off the tree if you prefer.
2. Who should avoid taking Mānuka as a herbal supplement?
Pregnant women should avoid taking mānuka due to its spasmolytic activity, which could induce contractions.
3. Is Mānuka safe to take for longer periods of time?
Long term use is fine.
However, monitor yourself for any issues.
Emma’s affinity for herbal medicine was driven by personal experiences where conventional therapies had not addressed the underlying causes of concern. This led the way for Emma to complete naturopathic studies, with a goal and focus to combine alternative and conventional patient care.
If you would like to learn more about Emma, see Expert: Emma Hartley.
References
(1) MacCulloch, I. (2007). Manuka. https://herbs.org.nz/site/assets/files/1209/manuka-1.pdf
(2) Department of Conservation. (n.d.). Mānuka/kahikatoa and kanuka. https://www.doc.govt.nz/nature/native-plants/manuka-kahikatoa-and-kanuka/
(3) Massey University. (n.d.). Manuka. https://www.massey.ac.nz/about/colleges-schools-and-institutes/college-of-sciences/our-research/themes-and-research-strengths/plant-science-research/new-zealand-weeds-database/manuka/
(4) Carlson, R. E., & von Fraunhofer, J. A. (2022). Manuka Oil Vs. Oral Pathogens: An Overview. EC Dental Science, 21, 148-154. https://ecronicon.net/assets/ecde/pdf/ECDE-21-01935.pdf
(5) Riley, M. (2003). Māori healing and herbal: New Zealand ethnobotanical book. Viking Sevenseas.
(6) Bubak, A. (2025). Manuka honey: Traditional uses and modern science. Science Rabbit. https://sciencerabbit.org/2025/03/18/manuka-honey-traditional-uses-and-modern-science/
(7) Donnelly, K. (2023). The NZ native – Mānuka. PhytoMed. https://www.phytomed.co.nz/blogs/phytobrief/manuka?_pos=3&_sid=572cdcbaf&_ss=r
(8) Lis‐Balchin, M., Hart, S. L., & Deans, S. G. (2000). Pharmacological and antimicrobial studies on different tea‐tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand. Phytotherapy Research: An International Journal Devoted to Pharmacological and Toxicological Evaluation of Natural Product Derivatives, 14(8), 623-629.
(9) Kapoor, N., & Yadav, R. (2021). Manuka honey: A promising wound dressing material for the chronic nonhealing discharging wounds: A retrospective study. National journal of maxillofacial surgery, 12(2), 233-237.
(10) Yan, G. Y., Zawawi, W., & Jemon, K. B. (2023). The effect of leptospermum scoparium essential oil combined with hyperthermia during in vitro dermal wound healing. https://science.utm.my/procscimath/wp-content/uploads/sites/605/2023/10/9_GOH-YU-YAN_78-87.pdf
(11) Campeau, M. E., & Patel, R. (2014). Antibiofilm activity of Manuka honey in combination with antibiotics. International journal of bacteriology, 2014(1), 795281. https://onlinelibrary.wiley.com/doi/full/10.1155/2014/795281
(12) Mathew, C., Tesfaye, W., Rasmussen, P., Peterson, G. M., Bartholomaeus, A., Sharma, M., & Thomas, J. (2020). Mānuka oil—a review of antimicrobial and other medicinal properties. Pharmaceuticals, 13(11), 343. https://pmc.ncbi.nlm.nih.gov/articles/PMC7694078/
(13) Al-Zharani, M. (2024). Growth inhibitory effect of Leptospermum scoparium (manuka) chloroform extract on breast and liver cancer cell lines. Journal of Advanced Veterinary and Animal Research, 11(2), 237. https://pmc.ncbi.nlm.nih.gov/articles/PMC11296193/pdf/JAVAR-11-237.pdf
(14) PhytoMed. (n.d.). Herbal monograph: Manuka (leptospermum scoparium).
(15) Drugs.com. (2024). Manuka oil. https://www.drugs.com/npp/manuka-oil.html
(16) Bardy J, Molassiotis A, Ryder WD, et al. A double-blind, placebo-controlled, randomised trial of active Manuka honey and standard oral care for radiation-induced oral mucositis. Br J Oral Maxillofac Surg. 2012;50(3):221-226.21636188
(17) Hawley P, Hovan A, McGahan CE, Saunders D. A randomized placebo-controlled trial of manuka honey for radiation-induced oral mucositis. Support Care Cancer. 2014;22(3):751-761.24221577
