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Treatment Evidence Explorer

What did the trials actually measure for each hair-loss treatment, and which of those trials apply to someone like me?

This shows what the trials measured — it does not rank options for you. Each card carries the published response rate, the number of people it was measured in, the published side-effect rate and the time the guide says results appear. The filters do not choose anything: they move options into a set-aside list and tell you the sourced reason, and you can read that list. The sorts order by one measured quantity at a time.

Which trial populations apply to you?
Could you become pregnant?

Finasteride, dutasteride and spironolactone cause birth defects. That label stays on those cards whatever you pick here.

Oral or topical?
Systemic side effects

Finasteride 1 mg

daily tablet oral

FDA-approved for men since December 1997.

  • Contraindication Causes birth defects — must not be taken by women who are or may become pregnant
  • On record Not approved for women — finasteride is not FDA-approved for female hair loss
What the trial measured
48% of men showed hair regrowth at 12 months (66% at 48 months)80–90% of men taking it have further loss slowed, per the AAD
Who it was measured in
n = over 1,500 men enrolled in the pivotal trials
Side effects, as published
4.2% had any sexual adverse event, against 2.2% on placebo
When the guide says results appear
4 months before improvement is typically noticed, per the AAD
Result window on a nought to twelve month scale: about month 4.
Evidence, as stated
FDA-approved for this use, on pivotal randomised trials

Read the finasteride guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • The FDA approved finasteride 1 mg (Propecia) on December 19, 1997, specifically for treating androgenetic alopecia in men. T01
  • finasteride promotes actual hair regrowth in about 48% of men at 12 months and 66% at 48 months T01
  • The American Academy of Dermatology reports that finasteride slows down further hair loss in approximately 80-90% of men who take it. T01
  • The pivotal clinical trials involved over 1,500 men with mild to moderate hair loss at the vertex (crown) and anterior mid-scalp regions. T01
  • sexual adverse events occurred in 4.2% of finasteride users versus 2.2% on placebo T01
  • The American Academy of Dermatology notes that it typically takes about 4 months to notice any improvement. T01
  • Finasteride is not approved for women and should never be taken by women who are or may become pregnant. T01
  • Women (finasteride is not FDA-approved for female hair loss) T01
  • finasteride 1 mg daily reduces scalp DHT levels by approximately 64% and serum DHT levels by 68% T01

Minoxidil for women, 5% foam or 2% solution

applied to the scalp topical

FDA-approved for women; the 5% foam since 2014.

  • Caution Not in pregnancy — minoxidil is not for pregnant women or those planning pregnancy
What the trial measured
45% more regrowth on 5% than on 2% in the trial61–86% of women improve on low-dose oral minoxidil
Who it was measured in
n = 381 women aged 18–49, in a 48-week double-blind placebo-controlled trial
Side effects, as published
4% report facial hair growth on topical; the same sentence gives 15% for oral
When the guide says results appear
4–6 months to visible improvement; maximum benefit at 12 months
Result window on a nought to twelve month scale: month 4 to month 6.
Evidence, as stated
FDA-approved for women, on a 48-week placebo-controlled trial

Read the women's minoxidil guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • FDA-approved for women (since 2014) W07
  • Women using 5% experienced 45% more hair regrowth than those using 2% W07
  • 61-86% of women show improvement with LDOM W07
  • A 48-week, double-blind, placebo-controlled trial of 381 women (ages 18-49) compared 5% solution, 2% solution, and placebo applied twice daily. W07
  • About 4% of women using topical minoxidil report facial hair growth; the rate is higher with 5% than 2% and highest with oral (15%). W07
  • Most women see visible improvement at 4-6 months, with maximum benefit at 12 months. W07
  • Pregnant women and those planning pregnancy should not use minoxidil. W07

Minoxidil 5%, topical

solution or foam, applied to the scalp topical

FDA-approved and available without a prescription.

  • Caution Stop if pregnant — our guide says to stop minoxidil and consult a doctor if you become pregnant
  • On record 1.4% — of the applied dose reaches the bloodstream
What the trial measured
59% improvement with minoxidil alone at 12 months45% more regrowth from the 5% solution than the 2% at 48 weeks30–40% of users are partial or non-responders
Who it was measured in
n not stated in our guide for this figure — we have not borrowed one from another study.
Side effects, as published
13.8% scalp irritation, usually from the propylene glycol in the solution15% unwanted hair growth; 0.5% stop treatment because of it
When the guide says results appear
2 months 52.3% notice results by then; full assessment at 4–6 months
Result window on a nought to twelve month scale: month 2 to month 6.
Evidence, as stated
FDA-approved for this use and sold over the counter

Read the minoxidil 5% guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • Minoxidil 5% is FDA-approved and clinically proven TO01
  • Studies show 94.1% improvement with combination versus 80.5% with finasteride alone and 59% with minoxidil alone at 12 months. T07
  • 5% solution produces 45% more hair regrowth than 2% at 48 weeks TO01
  • About 30-40% of users are partial or non-responders. TO01
  • Common side effects include scalp irritation (13.8%), usually from propylene glycol TO01
  • Hypertrichosis (unwanted hair growth) affects about 15% of users but causes only 0.5% to stop treatment TO03
  • Most users (52.3%) notice results by month 2, with full assessment at 4-6 months. TO01
  • If you become pregnant while using minoxidil, stop immediately and consult your doctor. W07
  • only about 1.4% of the applied dose reaches your bloodstream TO03

Low-dose oral minoxidil

daily tablet, 0.625–5 mg oral

Off-label: the oral drug is approved only for severe hypertension.

  • Caution Contraception required — women of childbearing potential need reliable contraception
What the trial measured
35–47% of patients had meaningful improvement
Who it was measured in
n = 2,933 patients across 27 studies in the 2025 meta-analysis
Side effects, as published
27% had some form of adverse event15–24% get hypertrichosis — hair growth elsewhere on the body
When the guide says results appear
6–12 months before response can be assessed
Result window on a nought to twelve month scale: month 6 to month 12.
Evidence, as stated
Off-label, on a 2025 meta-analysis of 27 studies

Read the oral minoxidil guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • Oral minoxidil is FDA-approved only for treating severe refractory hypertension T03
  • with about 35-47% of patients experiencing meaningful improvement T03
  • 2025 Meta-Analysis (27 Studies, 2,933 Patients) T03
  • Meta-analysis data shows approximately 27% of patients experience some form of adverse event. T03
  • The main side effect is hypertrichosis (excess hair growth elsewhere on the body), occurring in 15-24% of patients. T03
  • Most patients need 6-12 months to assess whether oral minoxidil is working. T03
  • Women of childbearing potential need reliable contraception T03
  • typically 0.625 mg to 5 mg daily for hair loss, compared to 10-40 mg or more for hypertension T03

Finasteride plus minoxidil

tablet plus scalp application oral + topical

Both components are FDA-approved; using them together is off-label.

  • Contraindication Causes birth defects — must not be taken by women who are or may become pregnant
  • On record Written for men — the guide states different considerations apply for women
What the trial measured
94.1% improvement at 12 months, against 80.5% and 59% for each alone92.4% of those men were stable or improved over 12 months
Who it was measured in
n = 502 men in a 12-month retrospective study of oral minoxidil 2.5 mg plus finasteride 1 mg
Side effects, as published
2–4% sexual side effects, the same rate as finasteride on its own
When the guide says results appear
3 months improvement seen at 3 and 6 months in one study, earlier than monotherapy
Result window on a nought to twelve month scale: month 3 to month 6.
Evidence, as stated
Off-label as a pair, on a 502-man retrospective study and a 7-RCT meta-analysis

Read the combination-therapy guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • FDA-approved components (used off-label together) T07
  • Studies show 94.1% improvement with combination versus 80.5% with finasteride alone and 59% with minoxidil alone at 12 months. T07
  • A large retrospective study (N=502) found 92.4% of men achieved stable or improved hair over 12 months. T07
  • A study of 502 men using combined oral minoxidil (2.5mg) and finasteride (1mg) for 12 months found T07
  • Sexual side effects: 2-4% (same as monotherapy) T07
  • One study found combination therapy showed improvement at both 3 and 6 months, while monotherapy showed later results. T07
  • Finasteride is not approved for women and should never be taken by women who are or may become pregnant. T01
  • You're a woman (different considerations apply) T07
  • Meta-Analysis of 7 RCTs (2025) T07

Topical finasteride 0.25%

spray or solution, applied to the scalp topical

Not FDA-approved; approved in Germany since December 2022.

  • Contraindication Teratogenic — contraindicated in women of childbearing potential
  • On record >100× lower — plasma concentration than oral; serum DHT down 34.6% vs 55.6%
What the trial measured
+20.2 hairs hair count at 24 weeks, against +21.1 for oral finasteride 1 mg
Who it was measured in
n = 458 men in the Phase III trial, over 24 weeks
Side effects, as published
2.8% had sexual adverse events, against 3.3% on placebo
When the guide says results appear
12 weeks to initial results; more by 24 weeks
Result window on a nought to twelve month scale: month 3 to month 6.
Evidence, as stated
Off-label in the US, on one Phase III randomised controlled trial

Read the topical finasteride guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • No, topical finasteride is not FDA approved for hair loss. T06
  • Germany approved a topical formulation in December 2022. T06
  • +20.2 hairs with topical versus +21.1 hairs with oral at 24 weeks T06
  • A landmark Phase III trial compared topical finasteride 0.25% spray, oral finasteride 1mg, and placebo in 458 men over 24 weeks T06
  • In the Phase III trial, sexual adverse events occurred in 2.8% of topical users versus 3.3% on placebo. T06
  • Expect initial results around 12 weeks, with more significant improvement by 24 weeks. T06
  • Topical finasteride is still contraindicated in women of childbearing potential due to teratogenic risk. T06
  • Plasma concentrations are over 100 times lower than oral, and serum DHT reduction is 34.6% versus 55.6% T06

Dutasteride 0.5 mg

tablet, daily or 2–3 times weekly oral

Off-label in the US; approved for hair loss in Japan, South Korea and Taiwan.

  • Contraindication Causes birth defects — neither dutasteride nor finasteride is approved for female hair loss
What the trial measured
35% reached moderate-to-marked improvement on thrice-weekly dutasteride21% reached the same mark on daily finasteride in that trial
Who it was measured in
n = 60 men in the 2025 randomised, investigator-blinded trial
Side effects, as published
1–3% decreased libido, listed for both dutasteride and finasterideNo significant difference in sexual side-effect rates between the two drugs
When the guide says results appear
6–12 months of consistent use before results are assessed
Result window on a nought to twelve month scale: month 6 to month 12.
Evidence, as stated
Off-label in the US, on a 2025 randomised investigator-blinded trial

Read the dutasteride comparison, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • FDA-approved for BPH (2001), NOT for hair loss in the US T02
  • Approved specifically for hair loss in Japan, South Korea, and Taiwan T02
  • Thrice-weekly dutasteride: 35% achieved moderate-to-marked improvement T02
  • Daily finasteride: 21% achieved moderate-to-marked improvement T02
  • 60 men with androgenetic alopecia T02
  • Decreased libido: 1-3% T02
  • Clinical trials comparing the two have not found significant differences in sexual side effect rates. T02
  • Expect 6-12 months of consistent use before assessing results. T02
  • Women (neither medication is approved for female hair loss, and both cause birth defects) T02
  • For hair loss treatment, dutasteride is used at a dose of 0.5 mg daily T02
  • dutasteride's long half-life allows effective treatment with 2-3 doses per week T02
  • Dutasteride's 5-week half-life means it takes several weeks of consistent dosing for serum levels to reach steady state. T02
  • A 2025 randomized, investigator-blinded trial provides some of the most recent comparative data between dutasteride and finasteride T02

Spironolactone 100–200 mg

daily tablet oral

Not FDA-approved for hair loss; prescribed off-label for female pattern loss.

  • Contraindication Contraindicated in pregnancy — risk of feminization of male fetuses
  • On record Not used in men — antiandrogen effects cause feminization
What the trial measured
56.6% overall improvement rate; 65.8% when combined with another treatment
Who it was measured in
n = 48 women in the 2025 randomised placebo-controlled trial (all also using minoxidil)
Side effects, as published
15–30% menstrual irregularity, the most common side effect2.8–3.8% of women stop taking it because of side effects
When the guide says results appear
6–12 months to results; best outcomes at one year or longer
Result window on a nought to twelve month scale: month 6 to month 12.
Evidence, as stated
Off-label, on a 2023 meta-analysis and a 2025 randomised trial

Read the spironolactone guide, the guide behind this card

The exact sentences these numbers came from, and which guide each is in
  • No, spironolactone is not FDA-approved for hair loss. T04
  • A 2023 meta-analysis found an overall improvement rate of 56.6%, with combination therapy (such as adding minoxidil) showing better results at 65.8%. T04
  • 48 women randomized to spironolactone 100 mg or placebo (all using minoxidil) T04
  • The main side effect is menstrual irregularity (15-30%), which is manageable. T04
  • Studies show only 2.8-3.8% of women discontinue spironolactone due to side effects T04
  • Results typically take 6-12 months to appear, with best outcomes at one year or longer. T04
  • Spironolactone is contraindicated during pregnancy due to risk of feminization of male fetuses. T04
  • Spironolactone is generally not recommended for men because its antiandrogen effects cause feminization, including breast enlargement and sexual dysfunction. T04
  • Spironolactone dosing for hair loss typically ranges from 50-200 mg daily, with most women taking 100-200 mg. T04
  • The most recent high-quality evidence comes from a 2025 RCT in premenopausal women T04

Different rows came from different studies with different endpoints, so a bigger number on one card does not mean a better outcome than a smaller number on another. What is comparable is what each trial set out to measure, and that is printed on every card.