Herbal Medicines

herbs in pestle

Last updated by Dr Sarah Brewer on

Plants contain a unique blend of chemicals, many of which have a beneficial, medicinal action, and herbal medicine is one of the most ancient complementary therapies. In fact, over a third of medically prescribed Western drugs are based on traditional plant remedies, such as aspirin (derived from the willow tree), morphine (opium poppy), digoxin (foxglove),  sodium cromoglycate (an asthma drug derived from the middle eastern herb, Ammi visnaga) and powerful anti-cancer treatments such as vincristine (from the rosy periwinkle) and paclitaxel (from the Pacific Yew Tree).

How herbal medicines work

Unlike prescribed drugs, which tend to contain a single, isolated, active ingredient, herbal medicines supply a blend of natural constituents that have evolved together and often have a synergistic action. They also tend to be more gentle, with less risk of side effects than prescribed drugs, although this is not always the case.

Different parts of different plants are used, such as the roots, stems, flowers, leaves, bark, sap, fruit or seeds depending on which has the highest concentration of active ingredients. Harvested plants are usually dried and ground to produce a powder from which may be made into an aqueous infusion (tea or tisane), an alcoholic solution (tincture) or packed as raw powder into tablets/capsules. Modern technology now allows extraction of the active ingredients using a solvent, which is then removed to produce more concentrated remedies. These residual solids are then dried and powdered to make tablets or capsules.

The concentration of active ingredient found in each plant varies depending on its genetic strain, soil mineral content, the time of harvesting, and the methods of cultivation used.

Solid extracts are described according to their concentration. A 10:1 extract, for example, means that ten parts raw herb was used to make one part of final extract. In theory, the more concentrated the extract, the more potent it is, although more substances may become lost through evaporation, so the concentration does not always reflect its activity. Because of this, it is usually best to select a standardised preparation where possible. Standardisation is a method that helps to ensure consistency so that each batch of a standardised product provides consistent amounts of selected active ingredients and provides the same benefit. Standardised remedies are also more likely to have good quality clinical trials supporting their use.

Traditional Herbal Medicines

In the UK, a number of traditional herbal remedies are now classed as medicines under the traditional herbal registration (THR) scheme. These are used to relieve or prevent symptoms of common minor ailments, including:

rhodiola tea

During the complex registration process, these traditional herbal medicines undergo extensive quality testing to ensure they are as safe and appropriate to use as other over-the-counter medicines.

Information on the front of each pack clearly explains which minor ailments can be treated by each herbal medicine, based on traditional use.

A Patient Information Leaflet inside each pack tells you when and how to take the herbal medicine and the recommended dosage. Important safety information is also included, such as potential side effects and known interactions with prescription drugs.

NB Do not take any herbal remedies during pregnancy or when breast-feeding unless specifically advised to by a medical herbalist or doctor.

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