An herb is a plant or plant part used for its scent, flavor or therapeutic properties. Herbal medicine products are dietary supplements that people take to improve their health. Many herbs have been used for a long time for claimed health benefits. They are sold as tablets, capsules, powders, teas, extracts and fresh or dried plants. However, some can cause health problems, some are not effective and some may interact with other drugs you are taking.

History of herbal medicine
Plants had been used for medicinal purposes long before recorded history. For example, ancient Chinese and Egyptian papyrus writings describe medicinal plant uses. Indigenous cultures (such as African and Native American) used herbs in their healing rituals, while others developed traditional medical systems (such as Ayurveda and Traditional Chinese Medicine) in which herbal therapies were used systematically.

Recently, the World Health Organization estimated that 80% of people worldwide rely on herbal medicines for some aspect of their primary health care. In the last 20 years in the United States, increasing public dissatisfaction with the cost of prescription medications, combined with an interest in returning to natural or organic remedies, has led to an increase in the use of herbal medicines. In Germany, roughly 600 - 700 plant-based medicines are available and are prescribed by approximately 70% of German physicians.

Why do herbs work?
For most herbs, the specific ingredient that causes a therapeutic effect is not known. Whole herbs contain many ingredients, and it is likely that they work together to produce the desired medicinal effect. Many factors determine how effective an herb will be. For example, the type of environment (climate, bugs, soil quality) in which a plant grew will affect its components, as will how and when it was harvested and processed.

Using herbs
The use of herbal supplements for medicinal purposes has increased dramatically over the past 30 years. Herbal supplements are classified as dietary supplements by the U.S. Dietary Supplement Health and Education Act (DSHEA) of 1994. The FDA defines a dietary supplement as "...any product taken by mouth that contains a so-called 'dietary ingredient' and its label clearly states that it is a dietary supplement." Per the provisions of DSHEA, herbal supplements -- unlike pharmaceutical drugs -- can be marketed without undergoing testing to prove their safety and efficacy. However, herbal supplements must be manufactured according to good manufacturing practices.

The most commonly used herbal supplements in the U.S. include echinacea (Echinacea purpurea and related species), St. John's wort (Hypericum perforatum), ginkgo (Ginkgo biloba), garlic (Allium sativum), saw palmetto (Serenoa repens), ginseng (Panax ginseng, or Asian ginseng; and Panax quinquefolius, or American ginseng), goldenseal (Hydrastis canadensis), valerian (Valeriana officinalis), kava (Piper methysticum), chamomile (Matricaria recutita), feverfew (Tanacetum parthenium), ginger (Zingiber officinale), evening primrose (Oenothera biennis), and milk thistle (Silybum marianum ).

Several herbs are often used together to enhance effectiveness and synergistic actions and to reduce toxicity. Health care providers must take many things into account when recommending herbs. For example, the species and variety of the plant, the plant's habitat, how it was stored and processed, and whether or not there are contaminants (including heavy metals and pesticides).

What is herbal medicine good for?
Herbal medicine treats many conditions, such as asthma, eczema, premenstrual syndrome, rheumatoid arthritis, migraine, menopausal symptoms, chronic fatigue, and irritable bowel syndrome, among others. Herbal supplements are best taken under the guidance of a trained health care provider. Be sure to consult with your doctor or pharmacist before self-treating. Some common herbs and their uses are discussed below.