Initially used to treat high blood pressure, minoxidil was the first medication approved by the FDA to treat male pattern baldness. By applying Rogaine (or a generic version) directly to the scalp twice a day, a man in the early stages of hair loss can often stimulate growth. The American Hair Loss Association points out that results of treatment with minoxidil are limited, but it still endorses using it in combination with other treatments or as an alternative if finasteride doesn't work.
The causes behind other types of hair loss -- including alopecia areata, telogen effluvium, anagen effluvium and traction alopecia -- and their treatment can be dramatically different. Hair loss is best treated in association with its underlying cause; therefore, it's recommend to seek medical help. Abnormal hair loss can also be a symptom of a more serious disease -- early diagnosis is strongly suggested in these cases.
The other main hair-loss treatment that was recommended by all four dermatologists I interviewed is finasteride, often called by its brand name Propecia. This FDA-approved medication is only available with a prescription, but these days, it’s found as a generic and ordered online after a virtual consultation, through start-ups like Hims, Keeps, and Lemonaid.