Hair loss has genetic, hormonal, inflammatory, and scarring causes, and the question what drug can grow hair is best answered by treatments that address specific mechanisms.
Two options with the strongest evidence are topical minoxidil and oral finasteride, which influence hair cycle regulation and hormone pathways rather than acting as generic stimulants.
This evergreen explainer outlines how these drugs work, what clinical studies show, who may benefit, typical timelines, common side effects, and realistic outcomes, while noting when to consider alternatives or combination approaches with medical guidance.