At a glance
Common name: Kawakawa, also known as pepper tree
Botanical name: Piper excelsum (older literature frequently uses Macropiper excelsum)
Plant family: Piperaceae, the pepper family
Part commonly discussed in herbal use: Leaves
Native range: Aotearoa New Zealand
Traditional context: Rongoā Māori, the Māori system of healing
Modern research: Investigations into its phytochemistry, biological activity and preliminary safety
Important distinction: A long history of traditional use and promising laboratory findings do not automatically establish the effectiveness or safety of every modern kawakawa preparation.
Getting to know kawakawa
Kawakawa is a native New Zealand shrub or small tree with a distinctive place in the country's natural and cultural landscapes. It is particularly recognisable by its glossy, heart-shaped leaves, prominent radiating veins and slender spikes of tiny flowers. As the fruits develop, they can become orange and aromatic.
The plant commonly grows beneath the canopy of coastal and lowland forests, where it benefits from shelter and relatively moist conditions. Depending on its environment, it can develop into a substantial shrub or small tree.
One familiar feature of kawakawa is the irregular holes often found in its leaves. These are usually caused by insect feeding and are a natural part of the relationship between the plant and its ecosystem. Although the holes have attracted popular folklore about selecting leaves for medicinal use, their presence should not be treated as a scientifically established measure of potency or quality.
Kawakawa belongs to the Piperaceae family, which also includes plants such as black pepper (Piper nigrum). Its peppery character reflects some of the chemistry found within the wider family, although kawakawa has its own distinctive chemical profile.
For botanical identification and distribution information, the New Zealand Plant Conservation Network provides a detailed species profile.
Kawakawa and rongoā Māori
Kawakawa is widely recognised for its role in rongoā Māori, the traditional Māori system of healing.
Rongoā is broader than the use of medicinal plants alone. It can involve plant-based remedies, physical therapies, spiritual dimensions of healing and relationships with people, whenua and the natural environment. Knowledge has been transmitted through generations, with practices, teachings and approaches differing among iwi, hapū, whānau and individual practitioners.
Historical accounts record a variety of medicinal uses for kawakawa. These include preparations involving the leaves or bark for stomach discomfort, toothache, cuts, wounds and other complaints. Leaves have also been described in traditional external applications and steam-based practices.
These accounts are valuable records of traditional knowledge, but they need to be understood in their original context. Historical descriptions may be incomplete, and they do not necessarily tell us the exact preparation, quantity, circumstances or wider treatment approach used by a particular practitioner.
It would therefore be misleading to reduce rongoā Māori to a collection of interchangeable recipes or to assume there is one universal way of using kawakawa.
For those wishing to learn about rongoā, guidance from knowledgeable Māori practitioners and appropriate cultural learning are important. Respect includes recognising that some knowledge is held within particular communities and is not simply a set of instructions for commercial or personal use.
Traditional use and contemporary herbal interest
Interest in kawakawa has grown well beyond its traditional setting. Today, it appears in products such as dried-leaf infusions, balms, oils and other botanical preparations.
This popularity reflects several things: its distinctive sensory character, its deep association with Aotearoa, the continuing importance of rongoā Māori and scientific interest in its chemical constituents.
However, traditional practice, culinary use, cosmetic application and medicinal treatment are not interchangeable categories.
For example, a product containing kawakawa may be marketed for skin care because it is a familiar botanical ingredient. That does not, by itself, demonstrate that the finished product can treat eczema, accelerate wound healing or relieve inflammatory disease. Such conclusions require evidence appropriate to the specific preparation and intended use.
The most useful approach is to appreciate the plant's cultural and botanical significance while asking clear questions about what a modern product actually contains and what evidence supports its intended purpose.
What is in kawakawa?
Research has identified a diverse range of naturally occurring compounds in kawakawa leaves and other plant parts. These include several broad groups of phytochemicals:
Amides and related compounds Kawakawa contains distinctive amides, including compounds structurally related to piperine, the pungent constituent associated with black pepper. Researchers have investigated these compounds for their sensory properties and biological activity.
Lignans Lignans are plant compounds found in many botanical species. Diayangambin is among the lignans identified in kawakawa and has attracted scientific interest because of its biological activity in experimental research.
Phenylpropanoids Compounds such as elemicin and myristicin have been identified in chemical analyses of kawakawa. Their presence illustrates why a plant's overall chemistry matters when considering its use, preparation and safety.
Flavonoids and other phenolic compounds These widely distributed plant constituents contribute to the chemical diversity of kawakawa. Some have been studied in other plant species for antioxidant and other biological activities, although findings from one compound or species cannot automatically be applied to kawakawa.
The proportions of these constituents are not necessarily constant. Research comparing different leaf sources has found variation in their chemical profiles. Growing conditions, plant material, processing, drying and extraction can all affect the composition of a botanical preparation.
This is one reason why a cup of leaf infusion, a concentrated extract and a topical product should not be assumed to have the same properties.
What does modern research tell us?
Scientific research into kawakawa is developing, but it remains important to distinguish chemical analysis, laboratory experiments, animal studies and human research.
Phytochemistry: establishing what the plant contains
Researchers have used analytical techniques such as liquid chromatography–mass spectrometry to investigate kawakawa's chemical composition.
One study identified numerous compounds in kawakawa leaf samples and found differences between samples from different sources and between aqueous and other extracts. This helps establish that kawakawa contains a complex mixture of constituents and that preparation methods affect what is extracted.
Chemical identification is a valuable first step. It does not, on its own, establish whether a preparation will produce a meaningful health benefit in people.
Laboratory research: exploring biological activity
Individual kawakawa constituents and extracts have been investigated in experimental systems, including studies of cellular activity and other biological effects.
Such research can help scientists identify promising directions for further investigation. However, a compound showing activity in isolated cells or under controlled laboratory conditions does not necessarily produce the same effect when someone drinks an infusion or applies a balm.
The amount required, absorption, metabolism, interactions among constituents and the concentration reaching the relevant tissue all matter.
For that reason, laboratory findings should be described as preliminary evidence, not as proof that kawakawa treats a particular disease.
Human research: investigating possible effects
A published human study examined short-term biological changes following kawakawa tea consumption in a small group of healthy volunteers. The researchers reported changes in several microRNAs and in the expression of genes associated with inflammatory signalling.
These findings are scientifically interesting because they help guide further research into how kawakawa might interact with biological processes.
Nevertheless, changes in molecular markers are not the same as demonstrating a clinical benefit. The study did not establish that kawakawa tea treats an inflammatory condition, relieves chronic pain or prevents disease. Larger and more clinically focused studies would be needed to answer such questions.
What about safety research?
A separate study examined the chemical composition and safety of kawakawa tea using laboratory analysis and animal testing. Under the specific conditions studied, the researchers did not observe adverse effects that led them to consider the tested tea preparation unsafe.
That is a useful early finding, but its limits matter. A study in rats cannot establish comprehensive human safety, and testing a particular leaf tea does not prove that concentrated extracts, essential oils or every commercially available formulation are equally safe.
The overall picture: Kawakawa has a substantial traditional history and an increasingly interesting scientific profile. The evidence is promising enough to justify further investigation, but it is not yet sufficient to support broad medical claims about its effects in people.
Different ways kawakawa is prepared
The form of a botanical product affects its composition, strength, use and potential risks. Kawakawa preparations should therefore be considered individually rather than as one uniform remedy.
Leaf infusions
Dried or fresh leaves may be used to prepare a hot-water infusion, including products intended for traditional or culinary use.
If choosing a commercial infusion, use a product intended for that purpose and follow its preparation instructions. Correct plant identification, clean processing, appropriate storage and clear ingredient information all matter.
A traditional preparation should not automatically be converted into a medicinal dose or a daily regimen for treating a health condition.
Topical balms and oils
Kawakawa is also found in skin-care products, including balms and infused oils. For these products, the finished formulation is important: the plant material, extraction method, base ingredients, preservatives and storage conditions can all influence quality.
A topical product's presence of kawakawa does not establish that it has been clinically demonstrated to heal wounds or treat a skin disorder. Choose products with clear labelling and intended-use instructions, and discontinue use if irritation develops.
Do not apply homemade or unverified herbal preparations to deep, infected or deteriorating wounds. Burns, serious skin infections and wounds that are not healing may require prompt medical assessment.
Concentrated extracts and other formulations
Concentrated extracts may contain constituents in proportions that differ substantially from those in a simple leaf infusion. Research findings from a tea preparation should not be used to infer the safety or effectiveness of a concentrated product.
Products should be evaluated according to their own composition, quality controls, intended route of use and supporting evidence.
Growing kawakawa at home
Kawakawa can be an attractive addition to an appropriate native planting or sheltered garden. Its broad, glossy leaves add texture, and its growth habit can suit areas that receive filtered light.
The New Zealand Plant Conservation Network notes that kawakawa can be propagated from fresh seed or semi-hardwood cuttings. It generally does well with dappled light and soil that drains freely while remaining consistently moist. It is also shade-tolerant, but sensitive to cold and frost.
For home gardeners, a sheltered position with suitable moisture and protection from harsh conditions is a sensible starting point. Local climate matters, particularly in colder inland areas.
Growing a plant for the garden is different from collecting it for medicinal use. A healthy-looking plant is not automatically suitable for consumption, and garden plants may be exposed to sprays, contaminated soil or animal waste. Only use botanical material for an intended purpose when its identity, growing conditions and suitability are known.
Harvesting with care and respect
Kawakawa is a native species, but that does not mean it is appropriate to collect it wherever it grows.
Before harvesting, consider the land's ownership, any applicable rules and the condition of the plant population. Obtain permission where required, avoid damaging plants and never assume that public land or a protected area is freely available for collecting.
When harvesting within a rongoā Māori context, follow the guidance and tikanga appropriate to that practice and community. Methods of harvesting and the knowledge surrounding them may differ. Learning from a knowledgeable practitioner is more appropriate than assuming general online instructions capture the full context.
For commercially sourced kawakawa, useful questions include:
- Is the botanical identity clearly stated?
- Is the plant part identified?
- Is the source and processing method explained?
- Are ingredients, storage instructions and intended use clearly labelled?
- Is there information about quality control and contamination testing where appropriate?
Good sourcing supports both consumer confidence and responsible relationships with native plant resources.
Safety considerations
Kawakawa's long history of use deserves recognition, but its safety should not be assumed across every preparation, dose or person.
Pregnancy and breastfeeding: Reliable human safety information is limited. Seek advice from a qualified health professional before using kawakawa medicinally during pregnancy or breastfeeding.
Children: Do not assume that an adult preparation or dose is suitable for a child. Obtain appropriate professional guidance before medicinal use.
Medicines and ongoing health conditions: Human interaction data for kawakawa are limited. If you take regular medicines, have a long-term health condition or are considering concentrated extracts, discuss the intended product with a qualified health professional or pharmacist.
Skin sensitivity: Stop using a topical product if you develop irritation, redness or another reaction. Check the full ingredient list, as the base oils, fragrances and other ingredients may also cause sensitivity.
Concentrated products: Do not assume that an extract, essential oil or highly concentrated preparation has the same safety profile as a leaf infusion. Avoid ingesting products unless they are specifically intended for that use.
Persistent or serious symptoms: Kawakawa should not delay assessment of severe pain, unexplained digestive symptoms, infected wounds, persistent skin problems or other symptoms that require investigation. Do not stop prescribed treatment in favour of a herbal product.
Limited evidence of interactions is not the same as proof that interactions cannot occur. Clear communication between a person, their practitioner and their wider healthcare team helps support safer decision-making.
Choosing kawakawa thoughtfully
When considering a kawakawa product, begin with its intended purpose rather than the strength of its marketing claims.
For a leaf infusion, look for correct identification, appropriate processing, transparent ingredients and clear preparation guidance. For topical products, pay attention to the full formulation, intended use and storage requirements. For concentrated extracts, ask what research supports that specific type of preparation, rather than relying on findings from tea or isolated compounds.
It is also worth considering the context in which you are using the plant. Cultural knowledge, traditional practice, botanical science and contemporary healthcare can each contribute useful perspectives, but they do not answer exactly the same questions.
A responsible approach respects rongoā Māori as a living body of knowledge while remaining honest about the limits of current scientific evidence.
In summary
Kawakawa (Piper excelsum) is an important native plant of Aotearoa New Zealand, recognised for its distinctive foliage, its place in rongoā Māori and its increasingly studied phytochemistry.
Historical accounts describe a range of traditional uses, while modern research has begun investigating the plant's chemical composition, biological activity and preliminary safety. Human research has explored short-term molecular responses, but convincing evidence for specific clinical benefits remains limited.
Kawakawa is best approached with curiosity and respect: know the plant, understand the preparation, choose products carefully and seek appropriate advice when medicinal use raises safety questions.
Its story is not simply one of a native herb being rediscovered by modern science. It is also a reminder that plant knowledge exists within cultural, ecological and practical contexts that deserve to be understood on their own terms.
Sources and further reading
1. New Zealand Plant Conservation Network — Piper excelsum botanical description, distribution, habitat and propagation. https://www.nzpcn.org.nz/flora/species/piper-excelsum-subsp-excelsum/ 2. Te Ara – The Encyclopedia of New Zealand — Rongoā: medicinal use of plants. Historical and cultural context for Māori plant medicine. https://teara.govt.nz/en/rongoa-medicinal-use-of-plants 3. Museum of New Zealand Te Papa Tongarewa — Māori medicine. An overview of rongoā Māori and recorded medicinal plant uses. https://www.tepapa.govt.nz/digital-museum/explore-digital-museum/maori/maori-medicine 4. Composition and safety evaluation of tea from New Zealand kawakawa (Piper excelsum) — Research examining chemical composition and safety in an animal model. https://pubmed.ncbi.nlm.nih.gov/30572092/ 5. Exploring the Chemical Space of Kawakawa Leaf (Piper excelsum) — Analysis of the chemical diversity of kawakawa leaf samples and extracts. https://pubmed.ncbi.nlm.nih.gov/36501198/ 6. Anti-inflammatory effects of kawakawa (Piper excelsum): An integrative mRNA–miRNA approach — Human dietary research investigating short-term molecular responses. https://pmc.ncbi.nlm.nih.gov/articles/PMC11606859/ 7. Health New Zealand — Rongoā Māori. Information on traditional practice, appropriate knowledge and safety considerations. https://www.healthnz.govt.nz/health-topics/tests-and-treatments/rongoa-maori This guide is educational and is not a substitute for individual medical advice or guidance from a qualified rongoā Māori practitioner.