A person was specially selected for training in the art of Māori medicine by a tohunga pu (expert) from the whare wananga (house of learning). Ailments were treated in a holistic manner - by spiritual healing, by the power of karakia (prayer), by the mana (power) of the tohunga, and by the use of herbs.
The knowledge of rongoa was considered tapu (sacred) and was passed onto a select few. Medicine was prepared separately from food, including the separate use of utensils. Remedies could be made from either a single plant or by a combination of many.
For the pre-European-contact Māori, forms of leprosy and tuberculosis might have been the only contagious diseases. Māori had no in-built immunity to diseases like influenza, measles, and the fevers that European contact brought.
Internal herbal treatment was used for respiratory ailments like asthma, bronchitis, and coughs; for stomach, bowel, and urinary tract problems; for menstrual and birthing difficulties; and for at least one form of tuberculosis.
External treatments using herbs were given for a wide range of skin complaints, including boils, burns, excema, leprosy, ringworm, and warts as well as for fractures and wounds.
Most of the information that is known about rongoa is from the writings of early settlers and missionaries who either discussed or observed the traditional use of the plants.
Different iwi (tribal groups) have different names for the same plants and alternatively the same name can be used for different plants. Sometimes this has caused confusion with the use being applied to the wrong plant. An example is kahikatoa (another name for manuka) that was confused with kahikatea, a similar name for a very different tree.
Some of the information relating to the medicinal use of plants has been supported through scientific studies and the study of the use of related plants in other parts of the world. An example is kawakawa, which has relatives that are used medicinally in other countries of the South Pacific and has been the focus of scientific research.
Below is information that illustrates the medicinal use of a few New Zealand plants. It has been taken predominantly from the recordings of early settlers and missionaries and is not intended for self-medication as in many cases it has not been verified.