Herbal medicine refers to the use of a plant's seeds, berries, roots, leaves, bark, or flowers for medicinal purposes. Herbalism has a long tradition of use outside of conventional medicine but is becoming more mainstream as improvements in analysis and quality control along with advances in clinical research show the value of herbal medicine in the treating and prevention of disease. Almost one quarter of current pharmaceutical drugs are derived from herbal preparations.
Herbal medicine is used to treat many conditions, such as asthma, eczema, premenstrual syndrome, rheumatoid arthritis, migraine, menopausal symptoms, chronic fatigue, irritable bowel syndrome, and some of the symptoms of cancer and chemotherapy. For example, one study found that 90% of arthritic patients use alternative therapies, such as herbal medicine.