Alopecia, or hair loss, can occur in several forms. One of the most common is "male pattern hair loss," or androgenetic alopecia. As one might expect from the name, this type of hair loss occurs most commonly in men, where it appears as the well-known receding hairline. It can also occur in women, however, generally in the form of overall hair thinning ("diffuse hair loss"). Conventional treatment includes the drugs minoxidil and finasteride, as well as medical diagnostic techniques to rule out potential underlying problems (especially in women).

Hair loss that occurs in patchy areas is referred to as alopecia areata. It can strike both men and women at any age, but usually starts during childhood. Alopecia areata typically starts with one or more small, round, smooth patches in the scalp or beard area. Rarely, it causes total body hair loss, a condition called alopecia universalis. Alopecia areata has no medical cure. However, in many cases, hair grows back on its own without treatment. Widespread hair loss is less likely to reverse itself. Corticosteroids injected under the skin may promote some hair growth, but the results usually don’t last. An interesting approach to the treatment of alopecia areata involves inducing mild allergic reactions using either nickel sulfate or the leaves of the plant Primula obconica.^1,2 It appears that when these substances irritate the skin they trigger new hair growth, but larger studies are needed to confirm the findings.

Other forms of hair loss include "anagen effluvium" and "telogen effluvium." Anagen effluvium is typically caused by chemotherapy, but may occur as a result of various medical conditions. Telogen effluvium is generally caused by severe physiological stress, such as major illness.