How it works
Minoxidil opens ATP-sensitive potassium channels in the dermal papilla, increasing blood flow and shifting follicles from telogen (resting) to anagen (growth). Mechanism is independent of androgen pathways.
The evidence
Decades of clinical use. 5% topical solution is standard for men; 2% or 5% for women. Low-dose oral minoxidil (0.25–5 mg) shows comparable or superior efficacy in recent trials, especially for women with poor topical adherence.
Typical dosing
Topical: 1 mL of 5% solution to scalp twice daily. Oral (off-label for hair): 0.25–2.5 mg daily under clinician supervision.
Side effects
Common
- Scalp irritation (topical)
- Initial shedding (4–8 weeks)
Less common
- Facial hair growth (oral)
- Lightheadedness (oral)
Rare
- Tachycardia, fluid retention (oral, dose-dependent)
Drug interactions
- Antihypertensives — additive blood-pressure lowering (oral)