Minoxidil is a topical medication and hair growth stimulant indicated for central (vertex) hair loss. It is one of two products licensed by the Medical Health and Regulatory Authority (MHRA) and approved by the Food and Drug Administration (FDA) for the treatment of hair loss in men and women.
The mechanism by which Minoxidil promotes hair growth is not fully understood. Minoxidil is a potassium channel opener and a vasodilator. It contains a functional group of nitric oxide chemical which may act as a nitric oxide agonist. It is assumed that by widening blood vessels and opening potassium channels, Minoxidil allows more oxygen, blood, and nutrients to the follicle. This may cause follicles in the telogen phase to shed, which are then replaced by thicker hairs in a new anagen phase.
Minoxidil has been clinically proven to be effective in the treatment of hair loss and stimulation of hair growth in men and women.
In a 12-month, double-blind, randomised clinical study of 79 men (Savin RC. J Am Acad Dermatol. 1987 Mar;16(3 Pt 2):696-704), total hair counts showed a mean increase of 144.2 hairs in Minoxidil users. The investigators’ visual assessment showed moderate to dense regrowth in 64% of these patients. In a 32-week, double-blind, randomized clinical study of 28 women (Whiting DA, Jacobson C. Int J Dermatol. 1992 Nov;31(11):800-4.), hair counts for patients in the Minoxidil group increased more than 15% from a baseline mean of 169 hairs to a final count of 195 hairs. Assessment of hair growth showed 60% of women using Minoxidil experienced minimal to moderate hair growth compared to 46% of placebo patients.
Minoxidil is generally well tolerated. Reported side effects include irritation, itching or redness at the treated area and unwanted hair growth elsewhere on the body.