Mention dance competitions to Kristy Bain, a 27-year-old advertising executive, and the bad memories come flooding back. As a ten-year-old she regularly attended jazz ballet classes and one year, before her troupe took part in a national contest, her teacher had the bright idea of buying some tanning pills and feeding them to the girls. She thought they'd look tanned and healthy in their leotards. The effect, however, was anything but attractive.

"Everything went orange – even the palms of our hands," recalls Bain. "And our knees were bright orange, like one of those safety jackets."

Fortunately for Bain and her friends, the pills had no lasting effect – but they were never going to produce a real tan. They would have contained carotenoids, chemicals that make carrots orange and tomatoes red. These compounds have no effect on skin cells, but at high doses are stored in fat layers under the skin, turning it orange.

Carotenoid supplements are not the only products to have been sold as tanning drugs over the years, but the others don't work either, or worse, present serious health hazards. Of course, there are always fake-tan lotions and sprays that stain the skin brown. However, these can be messy and time-consuming.

If pale and interesting doesn't cut it for you, don't give up hope. The past decade has seen a slow blossoming of serious research into new ways to pharmacologically stimulate the natural tanning process. And researchers have worthier aims than just pandering to vanity – products could also help cut the risk of skin cancer for fair-skinned people, which would be good news for those who work outdoors, as well as beach bunnies. What's more, they could also be a boon for people with medical conditions that make them susceptible to skin cancer, such as organ transplant recipients.

Just as Botox was originally launched as a medical therapy before becoming hugely popular as a beauty treatment, any genuine tanning drug could also explode onto the cosmetic market. The products still have several years of clinical trials ahead of them, but if they pass these tests, consumers should finally have that elusive natural tan in a bottle.

So why has it taken so long to develop tanning medications that might actually work? The natural tanning process is a complicated one – the result of our skin's love-hate relationship with sunlight. Our bodies need a certain level of UV radiation to allow keratinocytes (skin cells) to manufacture vitamin D, essential for healthy bones. But too much UV causes DNA mutations, which can lead to skin cancer.

To balance these conflicting requirements, evolution has come up with a natural sunscreen called melanin, a light-absorbing pigment manufactured by our body's melanocyte cells. Darker-skinned people, whose ancestors lived in sunnier climes, have melanocytes that work harder, producing more melanin. But most people make extra melanin in response to sunlight, producing a tan.

Only recently, though, have scientists discovered how melanocyte cells actually detect when you've been in the sun. When UV rays damage skin cells' DNA, repair enzymes "excise" or remove short snippets of the damaged DNA. In 1994, Barbara Gilchrest, a dermatologist at Boston University, discovered that it was these snippets that appeared to make melanocytes release more melanin.

This explains why our ancestors, after spending much of the day outside, were able to gradually build up their tans as summer approached. In short, they received the right amount of sunlight with minimal damage. But beach holidays, sun beds and migration have put a spanner in evolution's work.

Incidence of skin cancer has soared in recent decades. It is very common in white populations worldwide, but is also the highest rated type of cancer in South Africa. Most cases are curable cancers of the keratinocytes (the main skin cells), but a small proportion are deadly melanomas, or cancer of the melanocytes.

Despite a growing awareness of the dangers of sun exposure, many pale-skinned people still cannot resist the urge to tan. The sun-bed industry claims its devices provide a safer way to tan with less risk of burning, but many doctors dispute this, and anyway, users are still exposed to damaging UV rays.

"The problem is getting brown skin if you have white skin," says Stuart Humphrey, formerly the clinical development manager of EpiTan, an Australian firm trying to develop a genuine tanning drug. "The only option is to go out in the sun or a solarium and damage your DNA."

Certainly none of the pills or potions currently touted on the Internet or in health-food shops is likely to help. There are no products approved by drug regulatory agencies for use as tanning agents, but that doesn't stop firms selling their products as such, without any evidence that they work, or, in some cases, despite serious safety concerns.

For example, the most common carotenoid – canthaxanthin – is banned from sale as a tanning agent because it can cause problems ranging from liver damage to crystals building up in the eye. Another widely sold class of tanning pills contains tyrosine, an amino acid which boosts melanin production. But most people already have enough tyrosine in their bodies – and it makes no difference to whether they tan or not.

However, there is a class of medicines known as psoralens that actually do promote tanning, by binding to the cells' DNA and making the skin supersensitive to the sun. In 1959, John Howard Griffin used them to experience life as a black man in the southern US (and write a bestseller called Black Like Me). But psoralens have numerous side effects, including suppressing the immune system, so now they are only used to treat serious medical conditions such as severe psoriasis.

Despite the field's dubious track record, serious research into tanning biology continues. And our improved understanding of the mechanisms of skin damage has prompted work on a variety of protective approaches. A New York company called Applied Genetics Inc. Dermatics is developing a lotion called Dimericine, which contains a DNA repair enzyme designed to reduce skin cancer. Although it is initially being targeted at vulnerable patient groups, it could one day be widely used by sun worshippers.

The firm plans to apply for US regulatory approval to use the medicine in patients with xeroderma pigmentosum, a rare genetic disease that cuts people's ability to repair DNA damage from UV light, putting them at increased risk of multiple skin cancers. In a 30-patient trial, Dimericine reduced by one-third the incidence of a type of skin cancer called basal cell carcinoma.

AGI Dermatics is also testing Dimericine in kidney transplant recipients. People who have had organ transplants have a higher risk of cancer – about a hundredfold greater in the case of skin cancer – and even higher in sunny places such as South Africa. This is most likely because the immunosuppressive medications patients take to stop them rejecting their new organ reduce their immune system's ability to kill cancer cells.

Other firms are making progress. EpiTan is producing a compound called Melanotan, which stimulates the melanocyte cells to make melanin – our naturally occurring sunscreen. In a small, placebo-controlled trial, 65 people of European descent received 30 injections over three months. By the end, those who got the Melanotan injections were significantly more tanned, with roughly 50 percent more melanin in their skin than those in the control group. The tan lasted three weeks after the last injection, with the fairest individuals showing the biggest increase in melanin – even redheads developed a slight tan. What's more, the tan seemed to protect against sun damage in the same way as a normal tan, hinting that Melanotan may be able to prevent skin cancer. "You are not just getting brown, you are getting protection," Humphrey says.

The tan came at a price, though, with side effects such as nausea, vomiting and facial flushing severe enough to make one in six people who received Melanotan quit the trial. EpiTan managing director Ian Kirkwood confirms the company is now developing two new formulations that could cut side effects by delivering a continuous low dose. One is an implant that is inserted under the skin that produces a tan for about eight to 12 weeks, says Kirkwood. The implant is now being tested in patients with polymorphous light eruption, a condition in which even low levels of sunlight can cause painful blisters. The other formulation is a spray applied to a small patch of skin, where it is absorbed into the bloodstream.

Larger trials will be essential before medicine regulators can approve Melanotan. It would take decades to measure any effect on cancer rates, so trials will instead assess whether Melanotan prevents the tissue damage most likely to precede skin cancer, such as production of DNA snippets.

"If you had your own built-in sunscreen that reduces your lifetime UV exposure by a factor of two to four, it should theoretically reduce your skin cancer risk," says Antony Young, a skin photobiologist at King's College London. But Young points out the cancer protection afforded by a natural tan may be due to more than just colour. His studies suggest skin that tans easily is better at repairing DNA damage. There are also safety issues to consider. Melanotan stimulates melanocytes, the very cells that can transform into the deadliest type of skin cancer. So could it somehow push the cells in that direction? "Until we've had decades of human use, there can't be an answer," says Humphrey. "But years of work in the lab don't support the concept."

Designing a medicine to protect against skin cancer also raises the issue of whether it would encourage more sun worshippers and so increase their cancer risk rather than reduce it. And if any firm does get a tanning medicine approved, it will have to think carefully how to market it. The existing carotenoid and tyrosine supplements have given tanning pills a bad name. If a company claims its new drug really does produce a "natural tan", customers may take some convincing.

After her traumatic childhood experience, Kristy Bain could be one of them. "I have an abject fear of even thinking about getting a fake tan now," she says. But on second thoughts, she relents. "If I could look like I spent a month in Bali just by taking a pill, I'd give it a go." After all, a bit of colour in your cheeks can do wonders – just ask her old jazz ballet team. They won first prize.