Minoxidil was originally used as a medication to lower the blood pressure when ingested. A prominent side effect of hair growth was noted. The drug was then added to a solution for topical use to be applied to the scalp to treat androgenic alopecia. This is a condition of hair loss caused by male hormones, and can occur in men and women.
Formulations
Minoxidil is applied topically for hair loss. It is available in a liquid suspension at 2 percent for women and 5 percent for men. A foam suspension is also available for use. It was shown to be effective in a 2007 study in the "Journal of the American Academy of Dermatology" by EA Olsen, et al. Higher concentrations of minoxidil are available by prescription.
Use
Minoxidil is applied to the vertex of the head twice per day. The vertex is the upper back part of the scalp. It does not appear to be effective at the crown or temples at the front of the head, so it is not indicated to treat a receding hair line according to the National Institutes of Health.
Mechanism
The exact mechanism of action of minoxidil in treating male pattern hair loss is unknown. It is known to open potassium channels and dilate blood vessels. It is not thought to affect dihydrotestosterone, also known as DHT, or 5-alpha-reductase, the enzyme that converts testosterone to DHT. DHT plays a central role in male pattern hair loss, and some other hair loss medications, including finasteride, target the formation of DHT according to "Basic and Clinical Pharmacology" by Dr. Bertram Katzung.
Effects and Efficacy
Minoxidil appears to widen hair follicles and cause older hairs to fall out and newer, thicker hair, to grow in its place. The medication is not effective in everyone. If effective for a person, it takes several months to work. Once its application is stopped, hair loss will resume.
Side Effects
Topical minoxidil typically causes few prominent side effects. Some people develop irritated skin on the scalp. People with heart disease should use this medication with caution and under the supervision of a healthcare professional because minoxidil has effects on the cardiovascular system if it is absorbed, such as through a cut in the skin.
References
- "Journal of the American Academy of Dermatology"; A Multicenter, Randomized, Placebo-controlled, Double-blind Clinical Trial of a Novel Formulation of 5% Minoxidil Topical Foam versus Placebo in the Treatment of Androgenetic Alopecia in Men; Olsen EA, et al.; 2007
- National Institutes of Health: Minoxidil Topical
- "Basic and Clinical Pharmacology"; Bertram Katzung; 11th Ed; 2009
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