Around 95 per cent of all hair loss is caused by androgenetic alopecia, or 'male pattern baldness'. This form of hair loss, which can also affect women, albeit to a lesser degree, occurs when testosterone is converted into another male hormone, dihydrotestosterone (DHT), 5-alpha-reductase. Those fortunate enough to have a deficiency of this probably genetically determined enzyme won't suffer from this form of hair loss.
What doctors tell you
A common conventional treatment for male pattern baldness is minoxidil (Rogaine/ Regaine). Originally developed to treat high blood pressure, it was noted that it increased hair growth. This led to the development of topical minoxidil, available in concentrations of 2 or 5 per cent. The solution has to be applied at least twice a day for four months before any results can be seen.
In addition to the possible allergic skin reactions, there is also the risk of systemic effects due to the absorption of minoxidil through the scalp. These include blurred vision, chest pain, very low blood pressure, fast or irregular heartbeat, headache and weight gain, to name but a few.
Another drug commonly prescribed for androgenetic alopecia is finasteride (Propecia), which works by inhibiting 5-alpha-reductase. Oral finasteride has to be taken once daily for three months before its benefits can be noticed. But the cost of achieving that thicker, darker head of hair may well include impotence, loss of sexual drive or a reduced amount of ejaculate.