The term, phytomedicine, may also refer to the science of pathology and damage to plants, the causes thereof, their manifestations, development, dissemination, methods for maintaining plant health, and measures used to control plant diseases and their causes.
As terms referring to medicinal or dietary practices of using botanical products, herbalism, herbal medicine or phytotherapy are used interchangeably in many countries, including Canada, Norway, the United Kingdom, other countries in Europe and South America, South Africa, and the United States.
General practices include ancient methods of traditional Chinese medicine and Ayurveda. Practitioners of herbalism or phytotherapy are referred to as herbalists or phytotherapists. Products used in herbalism may be called herbal medicines, botanicals, natural health products, herbal remedies, herbal supplements, or phytotherapies.
Archaeological evidence indicates that the use of medicinal plants dates back to the Paleolithic age, approximately 60,000 years ago. Written evidence of herbal remedies dates back over 5,000 years, to the Sumerians, who compiled lists of plants. A number of ancient cultures wrote about plants and their medical uses in books called herbals. In ancient Egypt, herbs are mentioned in Egyptian medical papyri, depicted in tomb illustrations, or on rare occasions found in medical jars containing trace amounts of herbs. Among the oldest, lengthiest, and most important medical papyri of ancient Egypt, the Ebers Papyrus dates from about 1550 BC, and covers more than 700 drugs, mainly of plant origin. The earliest known Greek herbals come from Theophrastus of Eresos who in the 4th c. B.C. wrote in Greek Historia Plantarum, from Diocles of Carystus who wrote during the 3rd century B.C, and from Krateuas who wrote in the 1st century B.C. Only a few fragments of these works have survived intact, but from what remains scholars have noted a large amount of overlap with the Egyptian herbals. Seeds likely used for herbalism have been found in archaeological sites of Bronze Age China dating from the Shang Dynasty (c. 1600 BC–c. 1046 BC). Over a hundred of the 224 drugs mentioned in the Huangdi Neijing, an early Chinese medical text, are herbs. Herbs also commonly featured in the medicine of ancient India, where the principal treatment for diseases was diet. De Materia Medica, originally written in Greek by Pedanius Dioscorides (c. 40 – 90 AD) of Anazarbus, Cilicia, a Greek physician, pharmacologist and botanist, is a particularly important example of herbal writing; it dominated for some 1500 years until the 1600s.
The World Health Organization (WHO) estimates that 80 percent of the population of some Asian and African countries presently use herbal medicine for some aspect of primary health care. Pharmaceuticals are prohibitively expensive for most of the world's population, half of whom lived on less than $2 U.S. per day in 2002. In comparison, herbal medicines can be grown from seed or gathered from nature for little or no cost.
Many of the pharmaceuticals currently available to physicians have a long history of use as herbal remedies, including opium, aspirin, digitalis, and quinine. According to the World Health Organization, approximately 25% of modern drugs used in the United States have been derived from plants. At least 7,000 medical compounds in the modern pharmacopoeia are derived from plants. Among the 120 active compounds currently isolated from the higher plants and widely used in modern medicine today, 80% show a positive correlation between their modern therapeutic use and the traditional use of the plants from which they are derived.
In a 2010 global survey of the most common 1000 plant-derived compounds, 156 had clinical trials published. Preclinical studies (cell culture and animal studies) were reported for about one-half of the plant products, while 120 (12%) of the plants evaluated – although available in the Western market – had no rigorous studies of their properties, and five were toxic or allergenic, a finding that led the authors to conclude "their use ought to be discouraged or forbidden." Nine plants evaluated in human clinical research included Althaea officinalis (marshmallow), Calendula officinalis (marigold), Centella asiatica (centella), Echinacea purpurea (echinacea), Passiflora incarnata (passionflower), Punica granatum (pomegranate), Vaccinium macrocarpon (cranberry), Vaccinium myrtillus (bilberry), and Valeriana officinalis (valerian), although generally there were inconsistent, often negative results, and the studies were of low quality.