Skin creams that can undo the effects of time are a real possibility, say scientists. But cosmetics that wipe out wrinkles and ageing spots will have to be subject to the same testing and regulation as medicines. One substance shown to reverse the damage caused by exposure to the sun is already available, although only on prescription.

Retinoic acid, a drug mostly used in acne treatment, has been found to minimise wrinkles in rigorous scientific testing, with results published in scientific journals. Most other anti-ageing creams on the market have little or no effect, according to experts. Consultant dermatologist Professor Chris Griffiths, from the University of Manchester, said retinoic acid's anti-ageing properties were discovered in Argentina in the 1970s.

But retinoic acid can cause side-effects, including irritation, redness and dryness, which would be "a major problem" for any cosmetics company, and therefore is only available from private doctors on prescription. Some products contain a weakened form, he added, but often formulated so that they have little effect, he said yesterday.

Generally, dermatologists say, there is no proof that mass-marketed anti-ageing creams do any good and no incentive for the companies to develop and test products that might be more effective. Cosmetics escape regulation because they do not claim to have any effect on the body. If they did, they would have to go through the same regulatory hoops as medicines, involving randomised, controlled clinical trials where the creams can be tested against placebo.

Griffiths caused a stampede for Boots when he identified a skin cream in a television documentary that appeared to have a real effect on the skin in lab tests. He is now running what he believes is the first properly scientific randomised, controlled clinical trial on the product, Protect and Perfect by Boots. Thirty women have been using the serum and 30 have been using a placebo designed to look, smell and feel like the real thing. The results are being analysed.

Dr Richard Weller, a consultant dermatologist at Edinburgh Royal Infirmary, said he thought the study might persuade some of the companies to carry out scientific trials. "This is the first time there has been a really good clinical study," he said. "The cosmetics companies will answer to the market and their consumers. This [the response to the TV programme] has shown a demand from consumers for real testing of anti-ageing cosmetic products."