A repurposed blood-pressure tablet taken in very small daily doses to regrow hair. For pattern hair loss it works about as well as topical minoxidil and is easier to keep up with, increasing hair number and thickness in men and women. Unwanted body-hair growth is common; long-term safety is unknown. (Full Review)

Protocol

Dose

Men 2.5–5 mg/day

Women 0.625–1.25 mg/day; well below antihypertensive doses

Frequency

Once daily

Single daily dose; splitting generally unnecessary

Titration

Every 1–3 months

Titrate by response to ~5 mg/day maximum

Time to effect

Meaningful Regrowth

~6 months

Meaningful scalp regrowth typically appears

Fuller Results

12 months

Fuller results with continued daily use

Reduced Shedding

2–3 months

Early increase in shedding first is normal

Benefits

High: Increased hair density in male and female pattern hair loss; efficacy comparable to topical minoxidil; dose-dependent improvement in hair thickness and terminal hair

Medium: Improved long-term adherence versus topical treatment; benefit across other non-scarring hair loss types; adjunctive benefit in alopecia areata

Low: Support in scarring and inflammatory alopecias

Speculative: Enhancement of eyebrow, beard, and body hair; endocrine therapy-induced alopecia in cancer survivors

Contraindications

Pheochromocytoma

Pregnancy

Breastfeeding

Recent heart attack (within ~90 days)

Significant heart failure (NYHA III–IV)

Pericardial disease

Uncontrolled arrhythmia

Advanced kidney disease

Key Interactions

Other antihypertensives and vasodilators (alpha-blockers, PDE5 inhibitors)

Guanethidine

NSAIDs (ibuprofen, naproxen)

Sympathomimetic stimulants (pseudoephedrine, high-dose caffeine)

Blood-pressure-lowering supplements (L-arginine, L-citrulline, beetroot/nitrate, magnesium, potassium, omega-3, CoQ10, garlic)

Licorice root

Risk & Side Effects

High: Excess facial and body hair

Medium: Fluid retention and lower-limb swelling; increased heart rate and palpitations; initial increased shedding

Low: Postural hypotension and dizziness; headache; pericardial effusion and serious cardiac effects

Speculative: Unknown long-term cardiovascular effects of chronic low-dose use

Monitoring

Marker	Target	Why
Blood pressure	110–125 / 70–80 mmHg	Detects excess blood-pressure lowering
Resting heart rate	55–75 bpm	Catches drug-related increases in heart rate
Serum ferritin	50–100 ng/mL	Low iron worsens hair loss and blunts response
eGFR	>90 mL/min/1.73m²	Reduced kidney function slows clearance and raises fluid/cardiac risk
Serum potassium	4.0–4.5 mmol/L	Baseline check given the drug's action on potassium channels
TSH	1.0–2.0 mIU/L	Thyroid dysfunction is a common, correctable cause of hair loss
Body weight	Stable from baseline	Rapid gain flags fluid retention

Cadence: Blood pressure, heart rate, and swelling at 4–8 weeks after starting or a dose increase, then every 6–12 months once stable; photographic tracking of scalp density at ~6 and 12 months.

Qualitative Assessment

Reduced daily hair shedding (less on the pillow, shower drain, or brush)
Visible increase in scalp density, coverage, and hairline appearance over 6–12 months
Absence of bothersome facial or body hair, leg swelling, palpitations, or lightheadedness
Improved confidence and satisfaction with hair appearance

Oral Minoxidil for Hair Regrowth

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment