Finasteride Year-1 Outcomes: What Real Users Actually Experience

What the first 12 months looked like in the trials

Two double-blind, placebo-controlled 12-month trials enrolled 1,553 men aged 18 to 41 with mild to moderate male pattern hair loss, and 1,215 of them continued into blinded second-year extensions [1]. Hair was counted in a 1-inch (5.1 cm2) circle on the balding vertex, starting from a baseline of 876 hairs. At 12 months the finasteride group had 107 more hairs than the placebo group (P<0.001); at 2 years, 138 more [1]. Hair count held in the finasteride group while the placebo group lost hair progressively [1].

A separate 12-month randomized trial of 450 Chinese men with androgenetic alopecia reported improvement in 80.5% of men on finasteride 1 mg, 59% on 5% topical minoxidil, and 94.1% on both [3]. That trial reported the share of men improved rather than the 107-hair count difference, so the two results are not directly comparable.

What the label pins down: efficacy in bitemporal recession has not been established, Propecia is indicated for men only, it is not indicated for use in women, and pregnancy is a contraindication, with a warning that women who are or may be pregnant should not handle crushed or broken tablets [2].

How fast, and what counts as a response

The label says daily use for three months or more is generally necessary before benefit is observed, continued use is recommended to sustain it, and withdrawal leads to reversal of effect within 12 months [2]. In the trials, the best hair count compared with baseline came in the first two years, after which counts drifted slowly down but stayed above baseline through five years, and the gap over placebo kept widening: 277 hairs at five years, though by then only 219 men on finasteride and 15 on placebo were still being counted [2].

HealthRX.com offers finasteride 1 mg by prescription; the labeled dose is one tablet once daily, with or without food [2].

Side effects during year one

The Propecia label's Table 1 comes from three 12-month controlled trials with 945 men on finasteride and 934 on placebo, aged 18 to 41 [2]: decreased libido in 1.8% versus 1.3%, erectile dysfunction in 1.3% versus 0.7%, and ejaculation disorder in 1.2% versus 0.7%. Combined, 36 of 945 men on finasteride (3.8%) reported one or more of these versus 20 of 934 (2.1%) on placebo, p=0.04, and 1.2% versus 0.9% stopped because of a drug-related sexual event [2]. The label states resolution occurred in men who discontinued for these effects and in most of those who continued, and that the incidence of each fell to 0.3% or lower by the fifth year [2].

A self-administered sexual function questionnaire at month 12 found statistically significant differences favoring placebo in 3 of 4 domains: sexual interest, erections, and perception of sexual problems. There was no significant difference in overall satisfaction with sex life [2].

A meta-analysis of 15 randomized placebo-controlled trials covering 4,495 men put the relative risk of sexual dysfunction at 1.57 (95% CI 1.19 to 2.08) overall and 1.66 (1.20 to 2.30) for finasteride 1 mg [4].

The 5 mg results come from older men treated for prostate enlargement and should not be used to predict side-effect rates for men taking 1 mg for hair loss [2][5]. In the PLESS trial of men 45 to 78 with BPH, the 5 mg dose produced, in year 1, impotence in 8.1% versus 3.7% on placebo, decreased libido in 6.4% versus 3.4%, and decreased ejaculate volume in 3.7% versus 0.8%; in years 2 to 4 there was no significant difference between groups for impotence, libido or ejaculation disorder [5]. On 1 mg, median ejaculate volume fell 0.3 mL (-11%) versus 0.2 mL (-8%) on placebo after 48 weeks [2].

One more year-1 measurable: mean PSA fell from 0.7 to 0.5 ng/mL at month 12 in men aged 18 to 41, and the label says any confirmed increase from the lowest value while on treatment should be evaluated for prostate cancer even if it is still within the normal range [2].

Mood and suicidality reports

Neither Propecia nor Proscar carries a boxed warning [2][5]. The history matters because it is often garbled online. The June 2021 Propecia label listed postmarketing depression. On May 31, 2022 the FDA sent a safety labeling change order citing suicidal ideation and behavior plus additional sexual dysfunction and neuropsychiatric events, and the supplement approved August 1, 2022 changed the wording to depression, suicidal ideation and behavior [6]. The current Propecia label lists depression and suicidal ideation and behavior as postmarketing reports; the labels describe these reports as voluntary, from a population of uncertain size, with a causal relationship that cannot reliably be established [2][6].

The larger observational datasets come from older men treated mostly for prostate symptoms. In 93,197 Ontario men aged 66 or older, suicide was not increased (HR 0.88, 95% CI 0.53 to 1.45); self-harm was higher only in the first 18 months (HR 1.88, 1.34 to 2.64); depression was higher in the first 18 months (HR 1.94, 1.73 to 2.16) and after (HR 1.22, 1.08 to 1.37), with absolute increases of 17 self-harm and 237 depression cases per 100,000 patient-years [7]. In a Swedish register of 2,236,876 men aged 50 to 90, finasteride was associated with depression (HR 1.61, 1.48 to 1.75) but not suicide (HR 1.22, 0.99 to 1.49) [8]. Neither cohort is a young hair-loss population taking 1 mg, which limits how far the numbers transfer.

Why trial numbers may understate side effects

There is a documented problem with trial safety reporting. A 2015 JAMA Dermatology meta-analysis of 34 finasteride trials for androgenetic alopecia found that none had adequate safety reporting, 76% evaluated safety for one year or less, and funnel plots suggested systematic under-detection of sexual adverse effects [9]. Only 31% of 5,704 real-world finasteride-treated men would have met the pivotal trials' entry criteria [9].

Individual online reviews cannot establish how often an outcome occurs, because they are self-selected and carry no comparison group.

Stopping after year one

The label says withdrawal of treatment leads to reversal of effect within 12 months [2]. It also lists, among postmarketing reports, sexual dysfunction that continued after discontinuation, including erectile dysfunction, libido, ejaculation and orgasm disorders, and male infertility or poor seminal quality with normalization or improvement reported after discontinuation [2]. These come from voluntary reports, so they cannot give a rate [2].

Two small studies are usually cited for persistence. One interviewed 71 otherwise healthy men aged 21 to 46 who reported sexual side effects lasting at least three months after stopping; mean finasteride use was 28 months and mean persistence 40 months, in a post hoc, self-selected group that cannot show how common the outcome is [10]. The other measured neuroactive steroid levels in cerebrospinal fluid and plasma of 3 former users compared with 5 controls [11]. Neither establishes prevalence.

Adding minoxidil, and topical finasteride

In the 450-man trial, the combination of finasteride 1 mg and 5% topical minoxidil outperformed either alone at 12 months, with improvement in 94.1% versus 80.5% on finasteride and 59% on minoxidil [3]. For topical finasteride, a 7-day study in 24 men compared a 0.25% scalp solution used twice daily with the 1 mg tablet: plasma DHT fell about 68 to 75% with the topical and about 62 to 72% with the tablet, while plasma finasteride exposure was significantly lower with the topical product [12]. That finding covers one week of use, and no topical finasteride is FDA-approved [2].