Minoxidil tablets are FDA-approved to treat high blood pressure. Increased hair growth was observed as a side effect, and clinicians now prescribe minoxidil off-label at much lower doses for hair loss — typically a small fraction of the dose used for hypertension. Off-label prescribing is legal and common when a clinician judges it appropriate for an individual patient. Your dose is set by a U.S.-licensed clinician after reviewing your medical history.