Oral minoxidil, a low-dose blood-pressure drug used off-label, reliably grows thicker, denser hair in common hereditary hair loss, with results about on par with the scalp solution but without daily application. Its main drawback is unwanted face and body hair; fluid retention and a slightly faster heartbeat are less common. Benefits fade after stopping. (Full Review)

Protocol

Dose

Once daily

Women 0.625–1.25 mg/day; men 2.5–5 mg/day

Titration

Start low, increase slowly

Lowest effective dose; raise only if tolerated, as side effects are dose-dependent

Timing

Morning, consistent time

Timing not critical for efficacy; morning lets fluid or blood-pressure effects be observed while awake

Time to effect

Visible regrowth

3–6 months

With continuous daily use

Fuller results

~12 months

Fuller results around one year

Early shedding

First weeks

Temporary increased shedding; not a sign of failure

Benefits

High: Increased hair density in androgenetic alopecia; efficacy comparable to topical minoxidil

Medium: Improved hair shaft thickness; benefit across multiple non-scarring hair-loss types

Low: Convenience-driven adherence advantage

Speculative: Possible benefit in some scarring and inflammatory alopecias

Contraindications

Guanethidine

Pheochromocytoma

Recent heart attack (<90 days)

Significant heart failure

Pulmonary hypertension with mitral stenosis

Uncontrolled arrhythmia

Significant kidney impairment

Pregnancy or breastfeeding

Key Interactions

Other antihypertensives (ACE inhibitors, ARBs, calcium-channel blockers, vasodilators)

Diuretics and beta-blockers

NSAIDs (ibuprofen, naproxen)

Decongestants (pseudoephedrine, phenylephrine)

Blood-pressure-lowering supplements (potassium, magnesium, fish oil, garlic, coenzyme Q10, L-arginine)

Spironolactone

Risk & Side Effects

High: Unwanted excess body and facial hair

Medium: Fluid retention and swelling; increased heart rate

Low: Lightheadedness and postural hypotension; initial increased shedding

Speculative: Rare fluid around the heart or lungs

Monitoring

Marker	Target	Why
Resting heart rate	50–70 bpm	Detects minoxidil-related tachycardia
Blood pressure	~110–125 / 70–80 mmHg	Detects hypotension or interactions
Ferritin	40–70 ng/mL	Iron deficiency is a treatable cause of shedding
TSH	0.5–2.5 mIU/L	Thyroid disorders cause hair loss
Serum potassium	3.8–4.5 mmol/L	Relevant if combined with spironolactone
Body weight	Stable vs baseline	Rapid gain signals fluid retention

Cadence: Baseline, then at ~4 weeks and 3 months, then every 6–12 months

Qualitative Assessment

Reduced daily hair shedding after the initial adjustment period
Subjective increase in scalp coverage, fullness, and ponytail thickness
Improved confidence and reduced preoccupation with hair loss
Absence of bothersome swelling, palpitations, or lightheadedness
Visible regrowth on periodic standardized photographs

Oral Minoxidil for Hair Regrowth

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment