Alternative medicines are fast becoming the new mainstream as Britons increasingly turn to self-medication. Sales of herbal and homeopathic remedies in chemists, health stores and supermarkets have doubled in a decade and are now estimated to be worth £200m.

And there is no sign of a slowdown as consumers - the majority women aged more than 35 years - are expected to continue sweeping 'natural' pills, potions and ointments off the shelves, according to new research. Sales are predicted to reach £265m in the next four years. Growth has been particularly rapid in the past five years, according to the British Lifestyles report by researchers Mintel as the market acquires 'a greater reputation for offering legitimate alternatives to pharmaceutical-based treatments'.

One reason is the government encouraging people towards more self-medication by relaxing regulations on prescription-only drugs and promoting the role of the pharmacist. This has prompted more people to try alternative treatments they would not have considered had they visited their GPs. The industry will be given further legitimacy by new EU legislation which will require all over-the-counter herbal medicines in the UK to have either Traditional Herbal Medicines Registration or full Marketing Authorisation.

Herbal medicines, which contain extracts from plants and minerals, account for the fastest growth. Scientific tests have shown there is evidence that some could have a beneficial effect. More controversial are the homeopathic remedies, with critics claiming they offer nothing more than a placebo effect. Homeopathy is a system of therapy based on the concept that disease can be treated with drugs, in minute doses, thought capable of producing the same symptoms in healthy people as the disease itself does.

Today's high-octane lifestyles, longer working hours and increased stress are all said to have contributed to the love affair with complementary medicine. While one in five people reportedly suffers from stress and insomnia, many do not want to tell their doctors, to avoid black marks on their medical records. Others are worried about the stigma of taking antidepressants, while others fear developing an addiction to pharmaceutical drugs. For many, complementary medicines are the answer. The Jamie Oliver effect - highlighting the ill effects of diets stuffed with additives - is also believed to have spilled over into medicine, with consumers attracted by claims of natural goodness .

Edzard Ernst, professor of complementary medicine at Exeter University, said he was not surprised at the increase in sales. 'The last time I tested it, there were 40 million websites promoting complementary medicine. It's incessant.' Ernst, who last week challenged the Prince of Wales to withdraw two guides published by his Foundation for Integrated Health on the basis that they misrepresented scientific evidence, said that only claims by some herbal medicines were 'biologically plausible'.

'But homeopathy is not. It doesn't work, and that's that,' he said. 'And unless people are very certain of what they are taking, they could cause more harm than good. Some can interact with prescribed medicines.' In researching his latest book examining the efficacy of alternative medicine, he said his co-author, Dr Simon Singh, visited 10 homeopathic outlets asking for protection from malaria. 'And they all provided some, without exception. They were all very nice, but the nightmare begins when you return home with malaria.'

· Verdicts on the value of herbal remedies, according to Edzard Ernst, professor of complementary medicine at Exeter University

Herbal medicine: does it work?

Aloe vera

Used for: herpes, psoriasis, wound healing

Efficacy: poor

Ginseng

Used for: impotence, cancer, diabetes

Efficacy: poor

Milk thistle

Used for: hepatitis and liver disease caused by alcohol

Efficacy: medium

Evening primrose

Used for: eczema, asthma, menopausal problems, premenstrual syndrome, psoriasis

Efficacy: poor

Lavender

Used for: insomnia, anxiety

Efficacy: poor

Tea tree

Used for: fungal infections, insect bites, boils

Efficacy: medium