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Androgenetic Alopecia – Learn more about the most common form of hair loss

February 27, 2013

By: Marigdalia Ramirez-Fort, MD
Edited By: Karan Sra, MD

Androgenetic Alopecia is the most common form of hair loss, affecting both men and women. Androgenetic Alopecia is also known as Male Pattern Baldness (MPB) in men and Female Pattern Alopecia in women.

Androgenetic Alopecia, is caused by the effects of the sex hormone, dihydrotestosterone (DHT), on genetically susceptible hair follicles. DHT causes hair loss by shortening the growth phase of the hair cycle and decreasing the size of the hair follicles. The hair that is affected by DHT becomes shorter and finer until it eventually disappears. In men, DHT affects mainly the front, top, and crown of the scalp, sparing the back and sides. In women, the hair loss tends to be more generalized.


There FDA has approved two medications for hair loss, minoxidil (Rogaine) and finasteride (Propecia).

Minoxidil is applied directly to the scalp and can be purchased without a prescription. It is thought to work by increasing the length of time of the growth phase of thinning hairs. Minoxidil does not work in areas that are completely bald. The drug serves to thicken already existing hair, rather than to grow new hair. Minoxidil is applied directly to the affected areas of the scalp twice a day. The formulations come in a 5% solution or foam for men and 2% solution for women. The Minoxidil solution contains propylene glycol which may irritate the scalp and leave hair feeling sticky. The Minoxidil foam is in a glycerin and alcohol base and may cause less irritation with use. The development of facial hair can be a particular problem for female patients. Females should be careful when applying minoxidil to ensure that it does not drip down the temples and forehead. The full results of the medication may not be seen for 6 to 12 months.

Finasteride, a DHT blocking medication taken orally is more effective than minoxidil in treating hair loss. The major benefit of Finasteride is its ability to slow down or even halt hair loss. Finasteride does not grow hair in areas that are completely bald and works best in areas of thinning hair. Although the long-term ability of finasteride to maintain one’s hair is unknown, the majority of men find that after 5 years the medication is still working.