A scalp-applied, non-prescription drug that modestly slows pattern hair loss and regrows hair in men and women. It works best on early thinning and does little on bald or scarred areas. Results come slowly and last only with continued daily use; some people do not respond. Side effects are mainly scalp irritation and occasional unwanted facial hair. (Full Review)

Protocol

Dose

Men 5%; Women 2% or 5% foam

Solution twice daily; foam once daily

Application

Apply to dry scalp

Minimum effective volume; let dry fully; wash hands

Consistency

Daily, indefinite use

Consistency matters more than time of day

Time to effect

Regrowth begins

3–6 months

First visible new growth

Full assessment

12 months

Gains plateau by about one year

Less shedding

2–4 months

Daily shedding trends down

Benefits

High: Increased hair density in male pattern hair loss; hair regrowth in female pattern hair loss

Medium: Reduced shedding and slowed progression; increased terminal hair shaft diameter

Low: Adjunctive regrowth in alopecia areata and off-label sites

Speculative: Long-term preservation of the follicular stem-cell niche

Contraindications

Pregnancy and breastfeeding

Children under 18

Cardiovascular disease (recent heart attack, uncontrolled arrhythmia, advanced heart failure NYHA III–IV)

Pheochromocytoma

Active, broken, or infected scalp skin

Key Interactions

Prescription antihypertensives and vasodilators (guanethidine, minoxidil tablets)

Penetration-enhancing topicals (tretinoin, retinoids, anthralin, corticosteroids)

Barrier-disrupting over-the-counter topicals (salicylic acid, exfoliants)

Blood-pressure-lowering supplements (high-dose arginine)

Microneedling

Risk & Side Effects

High: Scalp irritation and contact dermatitis; initial increased shedding

Medium: Unwanted facial or body hair growth; loss of efficacy on discontinuation

Low: Systemic cardiovascular effects; allergic contact dermatitis

Speculative: Inadvertent transfer to children or pets

Monitoring

Marker	Target	Why
Ferritin (iron stores)	40–70 ng/mL	Low iron blunts regrowth and drives its own shedding
TSH	1.0–2.0 mIU/L	Thyroid dysfunction causes diffuse thinning that mimics or worsens pattern loss
Vitamin D (25-OH)	40–60 ng/mL	Low status is linked to hair-cycle disruption and poorer follicle health
Resting heart rate	50–70 bpm	Detects the rare tachycardia from systemic absorption
Blood pressure	<120/80 mmHg	Screens for the rare systemic vasodilator effect

Cadence: Reassess with photographs and self-report at ~4 months, 6 months, then every 6–12 months

Qualitative Assessment

Daily shedding trending down after the early surge
Visible density and scalp show-through in consistent lighting and camera angles
Hair-shaft feel and thickness (finer hairs maturing into thicker hairs)
Absence of persistent scalp itch, redness, or flaking
No new facial or body hair, swelling, lightheadedness, or racing heartbeat

Topical Minoxidil for Hair Regrowth

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment