Alternative medicine seems to be everywhere. Hardly a day goes by without a news story on this or that herbal or homeopathic remedy, mind-body treatment or another option from the mixed bag of therapies it offers. If you Google "alternative medicine", more than 40 million websites come up. We are faced with a very odd amalgam of too much and too little information. Too much of it is unreliable, promotional or even irresponsible, and too little of it is factual, objective and correct.

As a result, many people are confused, misinformed or even brainwashed. Consumers may try treatments that are ineffective or unsafe; alternative practitioners overestimate the effects of their treatments; conventional healthcare professionals may believe that all of alternative medicine is nonsensical; and NHS decision-makers are baffled by the morass of wishful thinking mixed with outright lies. Many of the claims of alternative medicine are more akin to those of the cosmetic industry than a branch of healthcare.

Meanwhile, the market for alternative treatments is growing. A recent Mintel report showed a 24% rise in sales of homeopathic remedies during the past five years while, for herbal medicines, the figure was as high as 40%. Several years ago, a BBC survey suggested that, collectively, Britons spend £1.6 billion each year on alternative medicine. Given the fact that, for many treatments, we don't even know whether and how they work, one may well wonder why. Why are we using more and more treatments which are essentially unproven?

One reason has already been mentioned: we are constantly bombarded with promotion. But the truth is more complicated than that, and there is a myriad of motivations to try some of these treatments. For instance, many of us are dissatisfied with certain aspects of conventional healthcare. Go to your GP and you may be given 10 minutes, a prescription and no time to even begin to speak about what really worries you. Go to a homeopath and you will have an hour's consultation with lots of time and all the empathy clinicians can muster.

Research shows that many people visit an alternative practitioner not because they want an effective therapy, but because they long for someone who listens to their concerns. In this sense, the striking popularity of alternative medicine is a bitter condemnation of conventional medicine.

This guide focuses on relaxation, and here is another important reason for the popularity of some of these treatments: they provide a pleasant and relaxing experience. Perhaps not colonic irrigation, well certainly not that, but think of aromatherapy, craniosacral therapy, hypnotherapy, meditation, massage, reflexology or reiki. In all these therapies the patient feels looked after and, in a way, loved.

Italian authors who recently published a review of 27 studies of relaxation training and concluded that "the results show consistent and significant efficacy ... in reducing anxiety". Many alternative therapies incorporate a degree of relaxation training and this may help people to cope with the stresses and anxieties of their lives.

But where is the scientific evidence? The Royal Society recently issued the following statement: "Complementary and alternative medicine, like conventional medicines, should be subject to careful evaluation of their effectiveness and safety. It is important that treatments ... are properly tested and that patients do not receive misleading information ... NHS provision for complementary and alternative medicine ... should be confined to treatments that are supported by ... evidence of both effectiveness and safety."

I do firmly believe that this is the right position. For the last 15 years, I have been banging on about the need for evidence and single standards. But does this also apply to someone paying for a session of aromatherapy to relax after a stressful day in the office?

Yes and no. Of course, we must make sure these treatments do not cause harm. But do we really need scientific proof that it is effective in causing a relaxation response in that person? Personally, I believe we should insist on scientific proof - but until the research is out, individual experience is the best guide we have.

· Edzard Ernst is the co-author of Trick or Treatment? Alternative Medicine on Trial (Bantam Press, £16.99)