Oral minoxidil in trichology

Minoxidil, a pro-drug has been used as an oral antihypertensive drug since the 1960s. Though it was initially introduced as a therapy to control hypertension, it became popular after its coincidental finding on the promotion of hair growth and stimulation of new hair production. This has led to the usefulness of minoxidil in treating several hair loss disorders in both topical and oral forms. In 1988, Food and drug administration (FDA) approved topical minoxidil (TM) 2% for the treatment of male androgenetic alopecia (AGA) and in 1992, it got approval for female pattern hair loss (FPHL). Since then the use of TM has increased tremendously. However, there are frequent reports of TM and/or its vehicle-induced contact dermatitis which has reduced the compliance in the patients resulted in a poor outcome. Oral minoxidil (OM) has been tried and found useful in AGA, alopecia areata (AA), traction alopecia (TA), chronic telogen effluvium (CTE), chemotherapy-induced alopecia, monilethrix, and several other alopecia’s; however, the exact mechanism of action and efficacy of oral minoxidil in these disorders remains undetermined. Also, when given in low dose, side effect profile of OM has been found comparable to that of TM. The above data was supported by case series, randomized control trials, and case reports with a low quality of evidence. In this review, we aimed to summarize the different indications of oral minoxidil. We reiterate the claim that high-quality studies are needed before advocating use of oral minoxidil in hair disorders.