Encyclopedia · growth stimulant
Minoxidil
The most widely used hair-growth treatment, available as a cheap over-the-counter lotion or foam and as a prescription tablet, with a mechanism that is still only partly understood.
What it is
Minoxidil was first a blood-pressure pill, and a 1980 letter noticed hair regrowth on it (Zappacosta 1980). Today it comes in several forms:
- Topical solution and foam, 2% and 5%. Sold over the counter in the US, UK and most of the EU. Solution contains alcohol and propylene glycol, the usual cause of itch and flaking. Foam is propylene-glycol-free.
- Oral tablets (2.5 mg and 10 mg in the US). Prescription-only and licensed only for severe hypertension, so use for hair is off-label (label). Where low-dose tablets are not sold, pharmacies often make capsules.
- Sublingual tablets and extended-release oral minoxidil, both still investigational.
The US over-the-counter men's label covers the top of the scalp (vertex) only and says the product is not intended for a receding hairline (label). For a side-by-side of the forms see minoxidil forms compared.
How it works
Minoxidil is a prodrug. It has to be sulfated into minoxidil sulfate to act on follicles; in cultured mouse whisker follicles minoxidil sulfate was 14 times more potent, and drugs that block sulfation stopped minoxidil from working (Buhl 1990). In humans the enzyme in the follicle is SULT1A1.
In animals it shortens the resting phase so follicles enter growth early, and it probably prolongs growth and enlarges follicles. That is why a temporary shed can occur in the first weeks (see the hair growth cycle). Proposed mechanisms include opening potassium channels, increasing blood-vessel growth factor, and prostaglandin effects, but these come mostly from cell and animal work and are not settled.
About 1.4% of topical minoxidil is absorbed through healthy scalp (Dias 2025).
Lesser-known mechanism findings (lab only)
Minoxidil may also act against androgens, but the evidence is cell culture only. In a human keratinocyte line, minoxidil lowered type 2 5-alpha-reductase gene expression to 0.22 times the untreated level (Pekmezci 2017). In testosterone-treated human dermal papilla cells, minoxidil lowered androgen receptor and CYP17A1 expression, raised aromatase (CYP19A1) activity, lowered DHT in the culture fluid from 346.86 to 267.43 pg/mL and raised estradiol from 12.01 to 13.22 pg/mL (Shen 2023). Neither study measured hair, so they do not show that minoxidil works as an antiandrogen in people, and they do not replace finasteride.
Other mechanism clues are also from mice and dishes: minoxidil activated beta-catenin in human papilla cells and modestly extended anagen in mice (Kwack 2011); most scalp sulfotransferase activity in macaques sat in the follicle (Baker 1994); and a 2004 review noted that the potassium-channel theory had never been shown in the follicle (Messenger 2004). In humans, a meta-regression of six studies tied each extra 1 mg/day of oral minoxidil to more hair and more side effects (Gupta 2022), and a larger early shed went with better results in 49 patients (Bi 2025).
What the studies show
- Topical 5% beat 2% and placebo in 393 men over 48 weeks, with about 45% more regrowth than 2% at week 48 and faster onset; 5% caused more itch (Olsen 2002).
- In 381 women, 5% and 2% both beat placebo on hair counts; 5% was better only on patient-rated benefit and caused more itch and facial hair (Lucky 2004).
- A Cochrane review of 47 trials (5,290 women) found about 13.2 more hairs/cm2 than placebo, with no difference between 2% and 5% in women (van Zuuren 2016).
- A meta-analysis found topical minoxidil added 16.7 hairs/cm2 over placebo, with investigator-rated response about 2.3 times likelier (Gupta 2015). Another found 5% and 2% in men, and 2% in women, all superior to placebo (Adil 2017).
- Foam without propylene glycol raised hair counts versus placebo in 352 men over 16 weeks (P<0.0001) (Olsen 2007).
- In 322 women, 5% foam once daily gave +23.9 hairs/cm2 versus +24.2 for 2% solution twice daily; the non-inferiority margin was narrowly missed (Blume-Peytavi 2016). A smaller 113-woman trial found foam non-inferior with less itch and dandruff (Blume-Peytavi 2011).
- In 300 Japanese men, 5% gave +26.4 versus +21.2 hairs/cm2 for 1% at week 16 (Tsuboi 2009).
- A 10% solution was no better than 5% in 90 men and was more irritating (Ghonemy 2021).
- In 45 men using foam, gains at the front and temples held to weeks 52 to 76 and were back to baseline by week 104, which the authors read as stabilising rather than continued growth (Kanti 2016).
- Direct comparisons suggest oral is not clearly stronger than topical. In 90 men, oral 5 mg and topical 5% showed no significant difference in terminal hair density, and 49% on oral developed hypertrichosis (Penha 2024). In 65 men and women, oral 1 mg and topical 5% did not differ (Asilian 2024). In 72 women, oral 0.25 mg and topical 2% both improved with no difference (Vahabi-Amlashi 2021); oral 1 mg versus topical 5% gave +12% versus +7.2% density, not significant (Ramos 2020).
- A meta-analysis of four such trials (279 people) found no density difference (standardised difference 0.02) and about double the hypertrichosis risk on oral (Sobral 2025). An earlier network meta-analysis had ranked oral 5 mg highest, but only through indirect comparisons (Gupta 2022).
- In 100 men, oral 2.5 mg did as well as 5 mg over 24 weeks (0.9 hairs/cm2 difference), with less ankle swelling and dizziness (Carvalho 2025). An open-label study of 30 men on 5 mg reported +35.1 hairs/cm2 but 93% hypertrichosis (Panchaprateep 2020).
- Combining finasteride with 5% minoxidil improved 94.1% of 450 Chinese men over 12 months, versus 80.5% on finasteride and 59% on minoxidil (Hu 2015). See finasteride.
- Sublingual 5 mg matched oral 5 mg in 110 men (+24.5 versus +21.8 hairs/cm2) with fewer palpitations (0% versus 9.3%) (Sanabria 2025). A 40-person phase 1b trial showed dose-dependent gains (Bokhari 2022), and 46 trans men on testosterone gained 15.7 more mid-frontal hairs/cm2 than placebo (Tang 2026). These come largely from one research group.
- The company behind extended-release oral minoxidil (VDPHL01) reported +30.3 and +33.0 versus +7.3 non-vellus hairs/cm2 at 6 months in men in an April 2026 press release; it is not peer reviewed (trial record).
- Eyebrows: 2% lotion beat placebo on all outcomes in a 40-person split-face trial (Lee 2014). Beard: 3% lotion twice daily beat placebo over 16 weeks in 48 men (Ingprasert 2016). For lashes, prostaglandin drugs have far better evidence; see bimatoprost.
- Gains are lost when you stop: after 96 weeks of treatment, hair weight and counts fell back to placebo levels within 24 weeks (Price 1999).
Response testing and boosters
A plucked-hair test of SULT1A1 activity predicted topical response with 95% sensitivity and 73% specificity in a retrospective pilot, but the authors work for the company that sells the test and related boosters (Goren 2014). For oral minoxidil the findings conflict: among 41 users, people with low follicular activity responded more often (85% versus 43%) (Jimenez-Cauhe 2024). Treat testing as unproven. See tretinoin for the other proposed booster.
How it's used in studies
- Topical, men: 1 mL of 5% solution or half a capful of 5% foam twice daily to the affected scalp. Labels say using more or more often will not improve results (label).
- Topical, women: 5% foam once daily or 2% solution twice daily (label).
- Low-dose oral, off-label: in a 2025 consensus of 43 hair specialists, common starting doses were 1.25 mg/day for adult women (range 0.625 to 5 mg) and 2.5 mg/day for adult men (range 1.25 to 5 mg). These reflect common practice, not strict limits (Akiska 2025).
- Sublingual trials used 0.45 to 5 mg once daily.
- Timeline: the men's label says results may appear at 2 months and some men need 4 months; the women's foam label says 3 months, with some needing 6. Oral benefit is expected from 3 months, later if there is an early shed (Akiska 2025).
- An early shed in the first weeks is common and, in one small study, a bigger shed went with a better result.
- Compounded capsules carry a dosing-error risk: twelve severe reactions (0.7% of about 1,700 prescriptions) came from capsules holding 10 to 100 times the prescribed dose, including a stroke after 1,000 mg instead of 1 mg (Moreno-Arrones 2022).
Side effects and safety
Topical
- Scalp itch, flaking and redness are the commonest effects, more with 5% solution than 2% (Olsen 2002). Patch testing usually points to propylene glycol rather than minoxidil, which is why foam suits itchy scalps.
- Unwanted facial or body hair is the main limit in women, in a dose-related pattern. It reverses after stopping, over one to five months depending on the site (Dias 2025).
- Systemic effects are rare. Stop and see a doctor for chest pain, fast heartbeat, faintness, sudden weight gain or swollen hands or feet. The foam is extremely flammable (label).
- Swallowing it is dangerous. A 60 mL bottle of 5% caused circulatory shock in several reports (Dias 2025).
- Cats and dogs: in 211 poison-centre cases, signs followed even a few drops or licks, often from licking an owner's skin or pillowcase, and 8 of 62 symptomatic cats died (Tater 2021).
Low-dose oral
- In 1,404 patients (retrospective, no control group), hypertrichosis was the commonest effect (15.1%) but only 0.5% stopped for it. Lightheadedness was 1.7%, fluid retention 1.3%, fast heartbeat 0.9%; 1.7% stopped for side effects and no life-threatening events occurred (Vañó-Galván 2021).
- Hypertrichosis is dose-related (6.7% at 0.25 mg versus 56.1% at 5 mg in pooled data), and women develop it at lower doses than men (Jimenez-Cauhe 2025).
- Ankle swelling is more likely above 1 mg, in women and in hot weather; it is managed with salt restriction, a diuretic or a dose cut.
- A meta-analysis found no significant blood-pressure change at 5 mg or less and a small heart-rate rise of 2.67 beats per minute (Chen 2025).
- Fluid around the heart (pericardial effusion) carries a boxed warning on the tablet label at antihypertensive doses (label). Reports at low doses are rare, and an ultrasound screen found small effusions in 5.8% of 51 low-dose users versus 6% of 49 controls (Kincaid 2024).
- Contraindications in the 2025 consensus: interacting drugs, past pericardial effusion or pericarditis, heart failure, pulmonary hypertension with mitral stenosis, pheochromocytoma, and pregnancy or breastfeeding (Akiska 2025).
- Pregnancy and breastfeeding: avoid. Oral minoxidil passes into breast milk, and the over-the-counter foam label warns it may be harmful in pregnancy or breastfeeding.
Bottom line
Topical 5% minoxidil is the cheapest proven treatment for pattern thinning in men and women, and it works only while you keep using it. Foam suits an itchy scalp, and once-daily foam is the usual women's regimen. Oral minoxidil gives about the same regrowth as topical in head-to-head trials, with more body and facial hair and a small risk of fluid retention; its real advantage is convenience. Men get more by adding finasteride. It thickens miniaturised hairs but cannot regrow follicles that are gone. Oral minoxidil, and any use around pregnancy, the heart or kidneys, is a prescriber's decision. Discuss with a doctor.
Fun facts
- Minoxidil may lower androgen receptor and DHT in papilla cells in the dish (Shen 2023), a lab-only finding.
- Your minoxidil can harm the cat: 8 of 62 cats that fell ill after exposure died (Tater 2021).
Studies 49
Olsen EA et al. A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol. 2002
Tested: 5% vs 2% topical minoxidil solution vs placebo, twice daily
Result: 5% was superior to 2% and placebo, with about 45% more regrowth than 2% at week 48 and faster onset; itch and irritation were more common with 5%.
Read the study ↗Lucky AW et al. A randomized, placebo-controlled trial of 5% and 2% topical minoxidil solutions in the treatment of female pattern hair loss. J Am Acad Dermatol. 2004
Tested: 5% vs 2% topical minoxidil vs placebo, twice daily
Result: Both strengths beat placebo on hair counts; 5% was better than 2% only on patient-rated benefit and caused more itch and facial hair.
Read the study ↗Olsen EA et al. A multicenter, randomized, placebo-controlled, double-blind clinical trial of a novel formulation of 5% minoxidil topical foam versus placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol. 2007
Tested: 5% minoxidil foam (propylene-glycol-free) vs placebo
Result: Hair counts rose significantly more than with placebo (P<0.0001) and the foam was well tolerated for up to 52 weeks.
Read the study ↗Blume-Peytavi U et al. A randomized, single-blind trial of 5% minoxidil foam once daily versus 2% minoxidil solution twice daily in the treatment of androgenetic alopecia in women. J Am Acad Dermatol. 2011
Tested: 5% minoxidil foam once daily vs 2% solution twice daily
Result: Foam was non-inferior to the solution and caused less itch and dandruff.
Read the study ↗Blume-Peytavi U et al. Efficacy and safety of once-daily minoxidil foam 5% versus twice-daily minoxidil solution 2% in female pattern hair loss: a phase III study. 2016
Tested: 5% foam once daily vs 2% solution twice daily
Result: Gains were +23.9 vs +24.2 hairs/cm2; the prespecified non-inferiority margin was narrowly missed.
Read the study ↗Tsuboi R et al. Randomized clinical trial comparing 5% and 1% topical minoxidil in Japanese men. 2009
Tested: 5% vs 1% topical minoxidil
Result: 5% gave +26.4 vs +21.2 non-vellus hairs/cm2 at week 16 (P=0.020).
Read the study ↗Show 43 more studies
Ghonemy S et al. Efficacy and safety of a new 10% topical minoxidil versus 5% topical minoxidil and placebo in male androgenetic alopecia. 2021
Tested: 10% vs 5% topical minoxidil vs placebo
Result: 10% was not better than 5% and was more irritating.
Read the study ↗Kanti V et al. Effect of minoxidil topical foam on frontotemporal and vertex androgenetic alopecia in men: a 104-week open-label clinical trial. 2016
Tested: 5% minoxidil foam, 24-week randomised phase then open-label extension
Result: Frontotemporal gains held to weeks 52 to 76 and returned to baseline by week 104, which the authors read as stabilising rather than continued growth.
Read the study ↗Price VH et al. Changes in hair weight and hair count in men with androgenetic alopecia after application of 5% and 2% topical minoxidil, placebo, or no treatment. J Am Acad Dermatol. 1999
Tested: 5% or 2% topical minoxidil vs placebo vs no treatment
Result: About 30% hair-weight gain was maintained while treated and was lost within 24 weeks of stopping.
Read the study ↗Gupta AK, Charrette A. Topical minoxidil: systematic review and meta-analysis of its efficacy in androgenetic alopecia. 2015
Tested: topical minoxidil vs placebo
Result: Total hair count rose by 16.7 hairs/cm2 more than placebo; investigator-rated response had a relative risk of 2.28.
Read the study ↗Adil A, Godwin M. The effectiveness of treatments for androgenetic alopecia: a systematic review and meta-analysis. 2017
Tested: minoxidil, finasteride and others vs placebo
Result: Minoxidil 5% and 2% in men and 2% in women were all superior to placebo.
Read the study ↗van Zuuren EJ et al. Interventions for female pattern hair loss. Cochrane Database Syst Rev. 2016
Tested: topical minoxidil and other treatments vs placebo
Result: Minoxidil gave about 13.2 more hairs/cm2 than placebo; there was no difference between 2% and 5% in women.
Read the study ↗Gupta AK et al. Relative efficacy of minoxidil and the 5-alpha reductase inhibitors in androgenetic alopecia treatment of male patients: a network meta-analysis. 2022
Tested: topical and oral minoxidil, finasteride, dutasteride (indirect comparisons)
Result: Oral minoxidil 5 mg ranked highest for terminal-hair gain at 24 weeks, but only through indirect comparisons.
Read the study ↗Penha MA et al. Oral minoxidil vs topical minoxidil for male androgenetic alopecia: a randomized clinical trial. JAMA Dermatol. 2024
Tested: oral minoxidil 5 mg vs topical 5% twice daily, double-dummy
Result: No significant difference in terminal hair density; oral looked better only on vertex photographs; hypertrichosis affected 49% on oral.
Read the study ↗Ramos PM et al. Minoxidil 1 mg oral versus minoxidil 5% topical solution for the treatment of female-pattern hair loss: a randomized clinical trial. 2020
Tested: oral minoxidil 1 mg vs topical 5% once daily
Result: Total density rose 12% on oral vs 7.2% on topical, not a significant difference; oral reduced shedding more.
Read the study ↗Vahabi-Amlashi S et al. A randomized clinical trial on therapeutic effects of 0.25 mg oral minoxidil tablets on treatment of female pattern hair loss. 2021
Tested: oral minoxidil 0.25 mg vs topical 2%
Result: Both improved (oral from 102 to 115 hairs/cm2) with no difference between groups.
Read the study ↗Asilian A et al. Clinical efficacy and safety of low-dose oral minoxidil versus topical solution in androgenetic alopecia: a randomized controlled trial. 2024
Tested: oral minoxidil 1 mg vs topical 5%
Result: No significant difference between oral and topical; topical was numerically better.
Read the study ↗Sobral et al. Efficacy and safety of oral minoxidil versus topical solution in androgenetic alopecia: a meta-analysis of randomized clinical trials. 2025
Tested: oral vs topical minoxidil
Result: Hair density did not differ (standardised difference 0.02); oral roughly doubled the risk of hypertrichosis (relative risk 2.01).
Read the study ↗Carvalho et al. Oral minoxidil 2.5 mg versus 5 mg for male androgenetic alopecia: a double-blind randomized clinical trial. 2025
Tested: oral minoxidil 2.5 mg vs 5 mg
Result: No difference in non-vellus hair density (0.9 hairs/cm2); ankle swelling and dizziness were more common on 5 mg.
Read the study ↗Panchaprateep R, Lueangarun S. Efficacy and safety of oral minoxidil 5 mg once daily in the treatment of male patients with androgenetic alopecia: an open-label and global photographic assessment. 2020
Tested: oral minoxidil 5 mg once daily, open-label
Result: Total hair count rose by 35.1 hairs/cm2; hypertrichosis occurred in 93% and ankle oedema in 10%.
Read the study ↗Vano-Galvan S et al. Safety of low-dose oral minoxidil for hair loss: a multicenter study of 1404 patients. 2021
Tested: low-dose oral minoxidil
Result: Hypertrichosis 15.1%, lightheadedness 1.7%, fluid retention 1.3%, fast heartbeat 0.9%; 1.7% stopped for side effects and no life-threatening events occurred.
Read the study ↗Moreno-Arrones OM et al. Serious adverse effects from compounding errors with low-dose oral minoxidil for alopecia treatment. 2022
Tested: compounded low-dose oral minoxidil
Result: Twelve severe reactions (0.7% of about 1,700 prescriptions) came from capsules holding 10 to 100 times the prescribed dose.
Read the study ↗Chen et al. Low-dose oral minoxidil does not significantly affect blood pressure: a systematic review and meta-analysis. 2025
Tested: low-dose oral minoxidil
Result: No significant change in systolic or diastolic blood pressure and a small heart-rate rise of 2.67 beats per minute.
Read the study ↗Kincaid CM et al. Evaluation of pericardial effusions in alopecia patients on low-dose oral minoxidil therapy. 2024
Tested: ultrasound screening for pericardial effusion
Result: Small effusions were found in 5.8% of users and 6% of controls.
Read the study ↗Bokhari L et al. Sublingual minoxidil for the treatment of male and female pattern hair loss: phase 1B clinical trial. 2022
Tested: sublingual minoxidil 0.45 mg vs placebo, plus open-label 1.35 and 4.05 mg
Result: Terminal-hair gains rose with dose (vertex +9, +26 and +88 per cm2 across the three doses).
Read the study ↗Sanabria B et al. Sublingual minoxidil 5 mg versus oral minoxidil 5 mg for male androgenetic alopecia: a double-blind randomized clinical trial. 2025
Tested: sublingual vs oral minoxidil 5 mg
Result: Same efficacy (total density +24.5 vs +21.8 per cm2) with fewer palpitations on sublingual (0% vs 9.3%).
Read the study ↗Tang et al. Treatment of androgenetic alopecia in transgender people receiving testosterone therapy with sublingual minoxidil: a randomized, double-blind, placebo-controlled trial. 2026
Tested: sublingual minoxidil 1.35 mg twice daily vs placebo
Result: Mid-frontal hair gained 15.7 hairs/cm2 more than placebo (P=0.03); no vertex difference at 24 weeks.
Read the study ↗Hu R et al. Combined treatment with oral finasteride and topical minoxidil in male androgenetic alopecia: a randomized comparative study in Chinese patients. 2015
Tested: finasteride vs 5% minoxidil vs both
Result: Improved: 80.5% on finasteride, 59% on minoxidil, 94.1% on the combination.
Read the study ↗Lee et al. Minoxidil 2% lotion for eyebrow enhancement: a randomized, double-blind, placebo-controlled, split-face comparative study. 2014
Tested: 2% minoxidil lotion vs placebo on opposite brows
Result: The minoxidil side did better on all eyebrow outcomes.
Read the study ↗Ingprasert S et al. Efficacy and safety of minoxidil 3% lotion for beard enhancement: a randomized, double-masked, placebo-controlled study. 2016
Tested: 3% minoxidil lotion 0.5 mL twice daily vs placebo
Result: Significant gains in hair count, photographs and self-rating.
Read the study ↗Tater KC et al. Topical minoxidil exposures and toxicoses in dogs and cats: 211 cases (2001-2019). J Am Anim Hosp Assoc. 2021
Tested: accidental exposure to topical minoxidil
Result: Signs followed even a few drops or licks; 8 of 62 symptomatic cats died.
Read the study ↗Jimenez-Cauhe J et al. Hair follicle sulfotransferase activity and effectiveness of oral minoxidil in androgenetic alopecia. 2024
Tested: plucked-hair sulfotransferase test and oral minoxidil
Result: 63.4% improved; people with low follicular enzyme activity responded more often (85% vs 43%), the opposite of the topical prediction.
Read the study ↗Goren A et al. Novel enzymatic assay predicts minoxidil response in the treatment of androgenetic alopecia. 2014
Tested: plucked-hair SULT1A1 activity test
Result: In a retrospective pilot the test predicted topical response with 95% sensitivity and 73% specificity; the authors work for the company that sells it.
Read the study ↗Zappacosta AR. Reversal of baldness in patient receiving minoxidil for hypertension. N Engl J Med. 1980
Tested: oral minoxidil
Result: Described regrowth of hair in a bald man taking minoxidil for hypertension.
Read the study ↗Buhl AE et al. Minoxidil sulfate is the active metabolite that stimulates hair follicles. J Invest Dermatol. 1990
Tested: minoxidil vs minoxidil sulfate
Result: Minoxidil sulfate was 14 times more potent than minoxidil, and drugs blocking sulfation stopped minoxidil but not minoxidil sulfate from working.
Read the study ↗Minoxidil tablets prescribing information. DailyMed
Tested: oral minoxidil tablets
Result: Labelled only for severe hypertension, with a boxed warning for pericardial effusion; not for use in nursing women.
Read the study ↗Akiska YM et al. Low-dose oral minoxidil initiation for patients with hair loss: an international modified Delphi consensus statement. JAMA Dermatol. 2025
Tested: low-dose oral minoxidil practice
Result: Common starting doses were 1.25 mg/day in adult women and 2.5 mg/day in adult men; pregnancy, past pericardial effusion and heart failure were contraindications.
Read the study ↗ClinicalTrials.gov NCT06724614. Extended-release oral minoxidil (VDPHL01) in men with pattern hair loss, phase 2/3. Veradermics
Tested: extended-release oral minoxidil vs placebo
Result: The company reported +30.3 and +33.0 vs +7.3 non-vellus hairs/cm2 at 6 months in a press release in April 2026; no peer-reviewed paper yet.
Read the study ↗Minoxidil 5% topical foam for women, over-the-counter drug facts. DailyMed
Tested: 5% minoxidil foam, half a capful once daily
Result: Results may appear at 3 months and some women need at least 6 months; hair loss begins again if use stops; the foam is extremely flammable and may be harmful in pregnancy or breastfeeding.
Read the study ↗Minoxidil 5% topical foam for men, over-the-counter drug facts. DailyMed
Tested: 5% minoxidil foam, half a capful twice daily
Result: Labelled for regrowth on the top of the scalp (vertex) only, not for a receding hairline; using more or more often will not improve results.
Read the study ↗Dias et al. Expanding the therapeutic landscape of minoxidil for androgenetic alopecia: topical, oral and sublingual formulations. 2025
Tested: topical, oral and sublingual minoxidil
Result: About 1.4% of topical minoxidil is absorbed through healthy scalp; swallowing a 60 mL bottle of 5% solution caused circulatory shock in several reports.
Read the study ↗Jimenez-Cauhe J et al. Review of low-dose oral minoxidil for hair loss. 2025
Tested: low-dose oral minoxidil
Result: Women develop hypertrichosis at lower doses than men (mean 1.4 mg vs 4.1 mg); fluid retention is seen in 1.3 to 10%, usually as ankle swelling.
Read the study ↗Pekmezci E, Turkoglu M. Minoxidil acts as an antiandrogen: a study of 5-alpha-reductase type 2 gene expression in a human keratinocyte cell line. Acta Dermatovenerol Croat. 2017
Tested: minoxidil at a non-cytotoxic concentration
Result: Minoxidil-treated cells expressed the type 2 5-alpha-reductase gene at 0.22 times the untreated level (p < 0.0001) on RT-qPCR; enzyme activity, DHT and hair were not measured.
Read the study ↗Shen Y et al. New target for minoxidil in the treatment of androgenetic alopecia. Drug Des Devel Ther. 2023
Tested: minoxidil versus testosterone-only control
Result: Network pharmacology predicted the androgen receptor, CYP17A1 and aromatase as minoxidil targets. In testosterone-treated human dermal papilla cells, minoxidil lowered AR and CYP17A1 expression, raised aromatase activity, lowered culture-fluid DHT from 346.86 to 267.43 pg/mL and raised estradiol from 12.01 to 13.22 pg/mL versus testosterone-only controls.
Read the study ↗Kwack MH et al. Minoxidil activates beta-catenin pathway in human dermal papilla cells: a possible explanation for its anagen prolongation effect. J Dermatol Sci. 2011
Tested: 3% topical minoxidil (mice); minoxidil in cell culture
Result: 3% minoxidil applied daily for 10 days modestly extended anagen and delayed catagen in depilated mice. In cultured human dermal papilla cells it raised beta-catenin reporter activity and nuclear beta-catenin, increased GSK3-beta, PKA and PKB phosphorylation, and induced Axin2, Lef-1 and EP2.
Read the study ↗Messenger AG, Rundegren J. Minoxidil: mechanisms of action on hair growth. Br J Dermatol. 2004
Result: Concluded that understanding of minoxidil's action on the follicle was very limited: it shortens telogen and probably prolongs anagen in animals; potassium-channel opening by minoxidil sulfate is favoured but no clear demonstration existed that KATP channels are expressed in the follicle; cell-culture effects include more cell growth, less collagen synthesis and more VEGF and prostaglandin production.
Read the study ↗Baker CA, Uno H, Johnson GA. Minoxidil sulfation in the hair follicle. Skin Pharmacol. 1994
Result: In scalp skin from 9 stumptailed macaques, the follicle held 47 to 84% (mean 61%) of minoxidil sulfotransferase activity, versus a mean of 18% in epidermis and 21% in dermis.
Read the study ↗Gupta AK et al. There is a positive dose-dependent association between low-dose oral minoxidil and its efficacy for androgenetic alopecia: findings from a systematic review with meta-regression analyses. Skin Appendage Disord. 2022
Tested: low-dose oral minoxidil
Result: Across six studies, each extra 1 mg/day of low-dose oral minoxidil was associated at six months with +47.1 total hairs/cm2, +9.1 terminal hairs/cm2 and +1.4 micrometres hair diameter, plus a 17.9-point higher hypertrichosis risk and a 4.8-point higher cardiovascular adverse-event risk. These are cross-study associations, not a randomised dose comparison.
Read the study ↗Bi L et al. Whether the transient hair shedding phase exists after minoxidil treatment and does it predict treatment efficacy? A retrospective study in androgenetic alopecia patients. J Dermatolog Treat. 2025
Tested: 2% or 5% topical minoxidil
Result: A temporary rise in shedding appeared within the first 12 weeks, lasting longer with 2% than 5% minoxidil. The size of the shed correlated with improvement in BASP grade in both groups and with trichoscopy improvement in the 5% group.
Read the study ↗Related
- FinasterideA prescription pill (and in some countries a scalp spray) that lowers DHT and is the best-proven drug for stopping male pattern hair loss.
- DutasterideA stronger cousin of finasteride that blocks both forms of the DHT-making enzyme and grew more hair than finasteride in head-to-head trials.
- SpironolactoneA cheap blood-pressure pill that blocks androgen receptors and is the most widely used off-label hormonal treatment for women's pattern hair loss.
- TretinoinA prescription acne and anti-ageing cream used off-label as a minoxidil booster because it increases minoxidil absorption, though the one randomised trial found no extra hair benefit.
- DiazoxideA potassium-channel-opening drug related to minoxidil that causes heavy fine body hair as a side effect and regrew hair on bald macaques, but has never been tested for human hair loss.
- LatanoprostA cheap glaucoma eye drop that lengthens and darkens eyelashes, with only a small pilot trial behind its off-label use on the scalp.
- BimatoprostA prostaglandin-like eye medicine that grows longer, thicker, darker eyelashes (and helps eyebrows), but did not work on the scalp.
- Microneedling for hair lossRolling or stamping fine needles into the scalp is a cheap add-on to minoxidil that helped in small trials, but it has not worked on its own and the largest trial found no extra benefit.
- Minoxidil forms comparedSolution, foam, oral tablets, sublingual and extended-release minoxidil deliver the same drug in different ways; this page compares them.
- Hair growth pipeline (2026)What is in clinical trials for hair loss as of October 2026, how far along it is, and how much to trust the early numbers.
- The hair growth cycleEvery scalp follicle cycles through growth, shutdown, rest and release on its own clock, which explains normal shedding, seasonal changes, maximum length and how pattern hair loss works.