Phytotherapy is the study of the use of extracts of natural origin as medicines or health-promoting agents. Phytotherapy medicines differ from plant-derived medicines in standard pharmacology. Where standard pharmacology isolates an active compound from a given plant, phytotherapy aims to preserve the complexity of substances from a given plant with relatively less processing.

Phytotherapy is distinct from homeopathy and anthroposophic medicine, and avoids mixing plant and synthetic bioactive substances. Traditional phytotherapy is a synonym for herbalism and regarded as alternative medicine by much of Western medicine. Although the medicinal and biological effects of many plant constituents such as alkaloids (morphine, atropine etc.) have been proven through clinical studies, there is debate about the efficacy and the place of phytotherapy in medical therapies.

Many herbs have shown positive results in-vitro, animal model or small-scale clinical tests,[1] while studies on some herbal treatments have found negative results.[2]

In 2002, the U.S. National Center for Complementary and Alternative Medicine of the National Institutes of Health began funding clinical trials into the effectiveness of herbal medicine.[3] In a 2010 survey of 1000 plants, 356 had clinical trials published evaluating their “pharmacological activities and therapeutic applications” while 12% of the plants, although available in the Western market, had “no substantial studies” of their properties.[4]

Even widely used remedies may not have undergone substantial clinical testing. In a review on herbal medicine in Malaria treatment, the authors found that “…better evidence from randomised clinical trials is needed before herbal remedies can be recommended on a large scale. As such trials are expensive and time consuming, it is important to prioritise remedies for clinical investigation….”[5]

Modern phytotherapy, following the scientific method, can be considered the study on the effects and clinical use of herbal medicines.