Herbal medicine is a type of medicine that is the most ancient in the world. Herbs have been utilized in all cultures throughout history. There is vast scientific documentation concerning their use for health conditions, including premenstrual syndrome, indigestion, insomnia, heart disease, cancer, and HIV.

  Herbs have always been imprescriptible to the practice of medicine. The word drug comes from the old Dutch word drogge meaning "to dry," as pharmacists, physicians, and ancient healers often dried plants for use as medicines. Today about 25 percent of all prescription drugs are still derived from trees, shrubs, or herbs. Some are made from plant extracts; others are synthesized to mimic a natural plant compound.

  The World Health Organization notes that of 119 plant-derived pharmaceutical medicines, about 74 percent are used in modern medicine in ways that correlated directly with their traditional uses as plant medicines by native cultures.

  Contemporary medicine doesn't apply pure herbs in its treatment of disease and other health disorders. One of the reasons for this is economic. By their very nature herbs cannot be patented, and drug companies cannot hold the exclusive right to sell a particular herb, therefore they are not motivated to invest any money in that herb's testing or promotion. The collection and preparation of herbal medicine cannot be as easily controlled as the manufacture of synthetic drugs, making its profits less dependable. Moreover, many of these medicinal plants grow only in the Amazonian rain forest or other politically and economically unstable places, which also influences the supply of the herb. In the United States has decreased the demand for herbal medicine, because Americans have been conditioned to rely on synthetic, commercial drugs to provide quick relief, heedless of side effects.

  Executive Director of the American Botanical Council, Mark Blumenthal, says that  the rebirth of interest in herbal medicine is a worldwide phenomenon, that appeared because of the growing concern of the general public about the side effects of pharmaceutical drugs, the impersonal and disgracing experience of modern health care practices, and a renewed approval of the unique medicinal value of herbal medicine.

  An educator in herbal medicine Donald Brown ( N.D., of Bastyr College, in Seattle, Washington), says that  the scope of herbal medicine ranges from mild-acting plant medicines such as chamomile and peppermint, to very potent ones such as foxglove (from which the drug digitalis is derived). In between these two poles lies a wide spectrum of plant medicine with significant medical applications. One need only go to the United States Pharmacopoeia to see the central role that plant medicine has played in American medicine.