The use of herbs to treat disease is almost universal among non-industrialized societies. A number of traditions came to dominate the practice of herbal medicine at the end of the twentieth century:
- The herbal medicine system, based on Greek and Roman sources
- The Ayurvedic medicine system from India
- Chinese herbal medicine (Chinese herbology)
- Unani-Tibb medicine
- Shamanic Herbalism
Many of the pharmaceuticals currently available to physicians have a long history of use as herbal remedies, including opium, aspirin, digitalis, and quinine. The World Health Organization (WHO) estimates that 80 percent of the world's population presently uses herbal medicine for some aspect of primary health care. Herbal medicine is a major component in all traditional medicine systems, and a common element in Ayurvedic, homeopathic, naturopathic, traditional Chinese medicine, and Native American medicine.
The use of, and search for, drugs and dietary supplements derived from plants have accelerated in recent years. Pharmacologists, microbiologists, botanists, and natural-products chemists are combing the Earth for phytochemicals and leads that could be developed for treatment of various diseases. In fact, according to the World Health Organisation, approximately 25% of modern drugs used in the United States have been derived from plants.
- Three quarters of plants that provide active ingredients for prescription drugs came to the attention of researchers because of their use in traditional medicine.[verification needed]
- Among the 120 active compounds currently isolated from the higher plants and widely used in modern medicine today, 80 percent show a positive correlation between their modern therapeutic use and the traditional use of the plants from which they are derived.
- More than two thirds of the world's plant species - at least 35,000 of which are estimated to have medicinal value - come from the developing countries.[verification needed]
- At least 7,000 medical compounds in the modern pharmacopoeia are derived from plants
