Baldness isn't just an embarrassment for the bald, or those of us who seem to be heading in that alarming direction. As medical science confidently rattles off miraculous cures for everything from influenza to impotence, even those medical scientists blessed with glossy, flowing locks have been left scratching their scalps in consternation that a cure still eludes them. It is more than two millennia since Cleopatra, queen of Egypt and amateur trichologist, proposed a mixture of mice, horses' teeth, bear grease and deer marrow as a remedy for thinning hair. Yet most modern day "cures" - and the costly thatch-weaved alternatives sported by certain ageing rock stars - have seemed no less ridiculous.
Until now, that is. Last week, the UK's Medicines Control Agency granted a marketing licence to the first ever oral drug that claims to reverse, not just slow, the traumatising onset of receding hair. Propecia - manufactured by the pharmaceutical giant Merck Sharp and Dohme - could be available here within months, offering the follicly deprived a promising alternative to desperate experiments with hypnotism, hairsprays and dubious potions pur chased over the internet, or gruesome surgical hair transplants.
Merck trumpets Propecia as an answer to the prayers of Britain's 7.5 million balding men. "Experts agree that the treatment is effective, and can increase scalp hair count and density in a cosmetically significant manner," the company proudly declares. "For many men experiencing hair loss, the availability of this choice represents a substantial improvement in their perceived quality of life and social wellbeing."
On the face of it, the medical evidence seems convincing. In worldwide clinical trials involving 1,879 men - all aged between 18 and 46 and suffering from "mild to moderate" hair loss - 86% experienced an increase in hair, or no hair loss, after two years. None experienced extra hair growth elsewhere on their bodies, the company stresses - unwittingly conjuring up images of hairy foreheads and uncontrollably bushy eyebrows.
"I think what we can say is that at the very least you probably won't lose hair," a Merck spokesperson says. "And, hopefully, you'll actually gain some more."
Propecia (the trade name for the drug finasteride) functions by suppressing an enzyme which converts the male sex hormone testosterone into dihydrotestosterone, a much more powerful bodily chemical which arrests hair growth. In effect, Propecia - whose hair-restoring properties were discovered while it was being used to treat enlarged prostates - grants a longer lifespan to follicles, which produce hair. They undergo temporary periods of inactivity even among the unbald, but DHT prompts them to pack up completely. Since a typical human sheds at least 100 hairs a day, a shiny pate can follow swiftly if they're not replenished.
So far, so promising. Even the not inconsiderable side effects - temporary impotence and lowered sexual drive - affected less than 4% of participants in the trials, with symptoms disappearing when the treatment ended. But there is a rather significant catch: as soon as you stop taking Propecia, hair loss reverts to its original rate. To call it a cure may indeed be going too far, according to Adrian Berkeley, general secretary of the Institute of Trichologists, which trains hair treatment practitioners and sets standards for the industry.
"Every few years, what is supposedly a miracle cure comes over the horizon - but it never is," he says. "The best one can say is that this will work for some people some of the time. But it's not a panacea: it won't cause hair to actually regrow in most cases, though it may go some way towards alleviating the condition."
The only true cure, he believes, is likely to be a genetic one, since male pattern baldness is itself a hereditary trait. Researchers in the United States have already isolated genes thought to be responsible for more severe and less common forms of hair loss, and it may be that a similar discovery will eventually bring salvation for the great unthatched.
In any case, it is likely to be some time before Britain's baldies have easy access to the drug. Though Propecia has been used in America since 1998, and is now eagerly ingested in 38 countries including France, Germany and Switzerland, Merck aren't pushing for it to be made available for NHS prescription - an extraordinary move for a drugs firm and one that is all the more surprising in the wake of the rows over Viagra and Glaxo's anti-flu drug Relenza. The Department of Health has been only too happy to agree. "Natural hair loss is not a health need, and cannot compare with our priorities of cancer, heart disease and mental health," a spokesman says.
Instead, Merck hopes to bring about a change in statute that would see Propecia brought onto Schedule 10 of the NHS regulations - a list of drugs which the NHS doesn't buy but which doctors are not precluded from prescribing to their patients, who would have to pay at least £23 a month - perhaps for the rest of your life, since the company views the drug as a long-term therapy. That may sound like a lot of money, but the company's banking on the assumption that there are many men out there who'd give their eye teeth to keep hold of the hair they've got left.
The public relations benefits of not being seen to be demanding a slice of the NHS's precious drugs budget are obvious, and the change, which might set an important precedent for the availability of other "lifestyle" drugs, could happen within the next few months. But it could, on the other hand, take several years.
In the meantime, there is one absolutely guaranteed way to halt hair loss in its tracks. On the plus side, unlike folk remedies, it doesn't require you to smear red ants, crushed nettles, horseradish or Marmite over your increasingly exposed scalp. On the minus side, it is castration.