This topically applied drug, minoxidil, has gained fame by acting as a hair follicle stimulant in male-pattern baldness.

The drug was initially discarded from its original intended use as an antihypertensive drug because of severe side effects. One of these was hair growth. Some clever boffin applied it directly to the skin and a whole new pharmaceutical angle is born.

Minoxidil works by producing a fine, downy hair growth in over 70 per cent of individuals but less than 15 per cent have an acceptable type of hair and to maintain it they need to continue to use the drug, at approximately £1 a day. The drug is absorbed and therefore side effects are possible as well as the compound causing local irritations.