Originally developed as an antihypertensive agent, it was approved by the FDA for treatment of MPHL as a 2% and 5% scalp lotion. The action mechanism of minoxidil on hair growth is still unclear. Recent studies suggest that it also enhances hair growth by increasing the production of prostaglandin E2. Topically applied, minoxidil increases hair weight with a less dramatic increase in hair counts. Adverse effects of minoxidil include skin irritation, hypertrichosis on the face and hands and tachycardia.