Minoxidil

Evidence by route

About this ingredient

Minoxidil is a piperidine-class vasodilator. In systemic cardiology used for severe arterial hypertension. In dermatology – first-line for androgenetic alopecia, the only FDA- and EMA-approved drug along with finasteride for hair loss treatment. Mechanism. The exact mechanism of hair growth is unknown. The active metabolite – minoxidil sulfate – opens ATP-dependent potassium channels in hair follicle cells, prolongs the anagen (growth) phase and shortens the telogen (rest) phase. Enhances scalp microcirculation. Where applied. 2% solution (for women) and 5% (for men and off-label in women), 5% foam. Brand names: Regaine (Spain), Rogaine (US). OTC in Spain, in Regaine 5% Espuma. Also oral low-dose (1.25–5 mg/day) – off-label, gaining popularity since 2017. Evidence base. The Kohler 2024 systematic review included 47 topical minoxidil RCTs – men with androgenetic alopecia gain 18–22 hairs/cm² over 6 months at 5%, women 12–16 hairs/cm² over 6 months at 2%. NICE 2023 and AAD 2022 recommend as first-line. Oral low-dose – Vañó-Galván 2021 meta-analysis showed comparable efficacy. Safety. Topical: irritation and contact dermatitis in 5–10% of patients (often to propylene glycol vehicle, not to minoxidil). Increased hair shedding (telogen effluvium) in the first 4–8 weeks is a normal response (cycle synchronization), hair regrows by 12–16 weeks. Systemic absorption is minimal (<1.7%). Oral form. Hypotension, tachycardia, body and facial hypertrichosis (unwanted in women), edema. BP and ECG monitoring is required at doses above 2.5 mg/day. Pregnancy and lactation – contraindicated. FDA Category C (topical), D (systemic). Fetal effect in pregnancy is not sufficiently studied; isolated cases of neonatal hypertrichosis have been reported. In lactation passes into breast milk. AAD 2023 and SEGO 2023 recommend avoidance. No alternative with proven pregnancy efficacy exists – defer alopecia treatment until lactation ends. Stopping treatment. After discontinuation the effect wanes over 3–4 months – hair returns to baseline. Treatment is lifelong.

Tolerability and safety

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