Minoxidil: Uses, Dosage, Side Effects

Reviewed byClearHormones Editorial Team, Medical-literature review

Last reviewed: 7/3/2026 · How we review →

Minoxidil is the only topical drug FDA-approved to treat female pattern hair loss (2% solution and 5% foam, sold over the counter as Women's Rogaine). Low-dose oral minoxidil — repurposed from the antihypertensive tablet Loniten — is used off-label by dermatologists. It works by prolonging the hair follicle's growth (anagen) phase; benefit fades if treatment stops.

⚠ Boxed warning

The oral tablet (Loniten) carries an FDA boxed warning: it may cause pericardial effusion (occasionally progressing to tamponade) and can exacerbate angina, so it is reserved for severe hypertension not manageable with other drugs. Topical minoxidil (Rogaine) has no boxed warning. Low-dose off-label oral minoxidil for hair loss uses far smaller doses, but the tablet's cardiac profile is why it is prescribed and monitored by a clinician.

Quick facts

Drug class: Vasodilator / hair-growth stimulant (potassium-channel opener)
Brand names: Rogaine, Women's Rogaine, Loniten
Forms: Topical solution 2% and 5%, Topical foam 5%, Oral tablet 2.5 mg and 10 mg (Loniten; low-dose use is off-label)
Commonly prescribed for: female pattern hair loss and menopausal hair thinning

What clinical trials show(3)

Published trial outcomes; sources listed below.

Lucky AW et al. (JAAD 2004) — topical minoxidil in women. 48-week RCT in 381 women: both 5% and 2% topical minoxidil were superior to placebo on hair count and investigator-assessed regrowth
Randolph M, Tosti A (JAAD 2021) — low-dose oral minoxidil review. Reviewed off-label low-dose oral minoxidil across hair-loss types; reported meaningful regrowth with a generally favorable safety profile at low doses
Ramos PM et al. (JAAD 2020) — 148 women, low-dose oral minoxidil. Descriptive series of women with female pattern hair loss reported improved density; hypertrichosis was the most common side effect

Go deeper(3)

Reference pages for this drug, built from FDA prescribing information.

Side effects →Incidence rates and management Dosage →Schedules, forms, missed doses Pregnancy →Pregnancy and breastfeeding guidance

Key drug interactions(3)

Top interactions by severity; always review your full medication list with a clinician or pharmacist.

Minoxidil key drug interactions
Interacts with	Severity	Mechanism
Guanethidine	major	Profound orthostatic hypotension with oral minoxidil — contraindicated combination per the Loniten label
Other antihypertensives	moderate	Additive blood-pressure lowering with oral minoxidil
Topical scalp products (retinoids, strong exfoliants)	minor	May increase absorption/irritation of topical minoxidil on abraded skin

Pregnancy at a glance

Minoxidil is generally avoided in pregnancy and breastfeeding. Cases of infant hypertrichosis have been reported after maternal use, and minoxidil passes into breast milk. Female pattern hair loss is not urgent, so treatment is typically deferred.

Full pregnancy and breastfeeding guide →

Sources(5)

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