How effective are medical treatments for common balding?

About one third of balding patients who use topical minoxidil solution experience significant (cosmetically obvious) hair regrowth. Any regrowth that occurs is only maintained while the drug is used. If therapy is stopped, hair density reverts to its pretreatment state. Oral finasteride, a 5α-reductase inhibitor, is somewhat more effective, and can be used in combination with topical minoxidil.

Rogers NE, Avram MR: Medical treatments for male and female pattern hair loss, J Am Acad Dermatol 59(4):547–566, 2008.