Health: Herbs that can cure you - or kill you

There are two types of herbalism - traditional and phytotherapy. However, it's only phytotherapy that is backed up by science, explains Professor Edzard Ernst in the fourth article of our series on complementary medicine
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Herbalism: what is it? The treatment of disease by plant products is called herbalism, or phytotherapy. Historically many drugs have relied on ants (Box 1), and herbalism is an element in virtually all medical cultures. In the West, herbalism had been driven to the fringe by powerful synthetic medications, but in recent years an unprecedented revival has emerged. Today, the total European market for herbal remedies is worth more than pounds 540m a year, with the UK getting only about 10 per cent of that.

There are two kinds of approach: traditional herbalism and rational phytotherapy. Traditional herbalists assess each patient in a "holistic" fashion, with little or no emphasis on conventional diagnosis. They will then prescribe herbs (often more than one) according to the individual being treated and the symptom that's the problem.

In their view, for instance, a "hot" condition would require treatment with a "cold" remedy. Several ethnic variations of this theme exist, eg Chinese herbalism, Kampo medicine from Japan, Hinduism's Ayurveda (from India). Phytotherapy, in contrast, uses plant extracts much as doctors use synthetic drugs; a given condition is likely to respond to a given (set of) plant extracts simply because of their pharmacological action. While the rationale for traditional herbalism is shaky - to say the least - that of phytotherapy is sound and scientific.

Most (traditional) herbalists in the UK are not medically qualified. To belong to the National Institute of Medical Herbalists, a minimum of four years of training is required. Most herbalists belong to a reputable organisation, but this is not obligatory. At present, about 1,000 herbalists are registered in the UK.

A consultation with a herbalist will cost you between pounds 20 and pounds 40. A herbalist will usually write a prescription, and will often sell remedies for home use. Some of these remedies can be expensive, and many of them taste unpleasant.

Most pharmacies and health food shops sell prescription-free herbal remedies which are mostly marketed as food supplements in the UK. Thus herbalism offers the opportunity for self-treatment.

What happens in a consultation?

A consultation with a herbalist is not dissimilar to one with a GP. They may dedicate more time to taking a detailed history, and they may ask questions which could seem unusual. Herbalists usually put less emphasis on physical examination and diagnostic tests than doctors.

What is herbalism used for?

According to a recent survey, British herbalists treat the following conditions most frequently:

Pre-menstrual symptoms.

Irritable bowel syndrome.

Menopausal symptoms.



Many traditional herbalists insist that they do not treat conditions, as diagnosed by mainstream medicine, but the whole individual. Thus two similar symptoms could receive entirely different prescriptions. So far, this type of approach has not been scrutinised in a rigorous scientific fashion.

In contrast, the more rational phytotherapeutic approach has been evaluated fairly extensively, through both basic pharmacological and clinical research. As a result, we know that certain herbal remedies are effective for certain conditions. The following list is based on systematic reviews (assessments of the totality of the available data, rather than single clinical trials), and is by no means complete:

Garlic lowers cholesterol levels and blood pressure.

Ginkgo biloba can delay clinical deterioration in Alzheimer's.

Echinacea (a plant that grows in North America) can boost the immune system, which, in turn, helps to combat infections such as the common cold.

Horse chestnut seed extracts can improve subjective symptom signs of varicose veins.

Kava kava (the root of a popular South Seas plant) reduces anxiety.

St John's wort eases symptoms of mild or moderate depression.

Generally, the scientific evidence for this type of phytotherapy is more compelling than for any other branch of alternative medicine.

What are the potential risks?

The remedies named above are not associated with serious side-effects. But, generally speaking, herbal treatments are certainly not free of side- effects. Like other powerful drugs, they can help and harm.

Allergies, toxic effects, carcinogenic effects and drug interactions are perhaps the most frequent risks. Moreover, remedies from Asia have repeatedly been reported to be contaminated with heavy metals or powerful synthetic drugs.

The best way to avoid these problems is to stick to quality products from reputable manufacturers. They offer remedies that are of known, constant strength, and are safe if taken as recommended.

Seeing a non-medically-qualified traditional herbalist can be associated with indirect risks if she or he does not know the limits of their medical competence, eg altering prescribed drugs, losing precious time in cases of severe disease.

Phytotherapy is relatively well supported by rigorous research. But some herbal remedies are also associated with serious risks. Therefore - on balance - the well informed use of herbal treatments can often be of more benefit than harm.

Next week: homoeopathy

Where to go for help

General Council and Register of Consultant Herbalists, Grosvenor House, 40 Sea Way, Middleton-on-Sea, West Sussex P022 7SA.

National Institute of Medical Herbalists, 56 Longbrook Street, Exeter EX4 6AH.

School of Phytotherapy, Bucksteep Manor, Bodle Street Green, Near Hailsham, East Sussex.

British Herbal Medicine Association, Sun House, Church Street, Stroud, Gloucestershire GL5 1JL.

Recommended reading

For "insiders" with prior knowledge:

Schulz V, Hausel R, Tyler VE, Rational Phytotherapy, Springer Berlin 1996

For beginners:

Fugh Berman A, Alternative Medicine: What works, Odonian Press, Tucson, Arizona 1996

Medicinal plants

Plant source Derived drug & Common use

Atropa belladonna (deadly nightshade) atropine (eye drops)

Camellia sinensis (camellia) theophylline (respiratory diseases)

Cinchona ledgeriana (cinchona) quinine (anti-malaria)

Digitalis purpurea (purple foxglove) digitoxin (heart drug)

Ephedra sinica (ma-huang) ephedrine (nasal decongestant)

Papaver somniferum (opium poppy) morphine (painkiller)

Rauwolfia serpentina (rauwolfia) reserpine (for hypertension)

Herbal Side-effects

Side-effect/reaction Example

Allergic Royal jelly: bronchospasm, several deaths.

Toxic Pennyroyal: toxic to the liver, several deaths.

Pharmacologic Yohimbine: heart rate, blood pressure, anxiety.

Mutagenic Laxatives such as senna: risk of colon cancer.

Contaminants found in some herbal (mainly Asian) remedies: arsenic; ; cadmium; diazepam (tranquilliser); diclofenac (painkiller); diuretics; ephedrine (heart stimulant); lead; mercury; steroids; thallium (a rat poison); theophylline (for chest diseases), zinc.