Finasteride Mental Health and Mood Impact: What the Evidence Actually Shows

Does finasteride carry a boxed warning for depression or suicide?

No. Neither Propecia nor Proscar has a boxed warning for depression or suicide [5][2]. Depression and suicidal ideation appear in section 6.2, Postmarketing Experience [5][2].

The wording has a dated history. The June 2021 Propecia label listed postmarketing 'Nervous System/Psychiatric: depression'. On May 31, 2022 the FDA sent a Safety Labeling Change order under section 505(o)(4) of the FD&C Act citing new safety information on the risk of suicidal ideation and behavior, additional risk of sexual dysfunction and psychoneurocognitive adverse events. Supplement S-030, approved August 1, 2022, changed the entry to 'depression, suicidal ideation and behavior' [1]. The current Propecia label, effective October 14, 2024, carries that wording [5]; the current Proscar label, effective March 18, 2026, lists depression and suicidal ideation [2]. The Propecia and Proscar labels describe these as voluntary postmarketing reports from a population of uncertain size and state that a causal relationship cannot reliably be established [5][2].

The Propecia label directs one 1 mg tablet once daily, with or without food [5]. HealthRX.com offers finasteride 1 mg by prescription.

What the large cohort studies found

The Ontario study followed 93,197 men aged 66 or older who started a 5-alpha reductase inhibitor, mostly for prostate enlargement, alongside matched men who did not. Completed suicide was not significantly associated with treatment (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). New depression was higher in the first 18 months (HR 1.94, 1.73 to 2.16) and modestly higher afterward (HR 1.22, 1.08 to 1.37). In absolute terms that was 17 extra self-harm events and 237 extra depression diagnoses per 100,000 patient-years [3].

The Swedish register study included 2,236,876 men aged 50 to 90, of whom 70,645 started finasteride at a median age of 73. Depression was diagnosed more often (HR 1.61, 95% CI 1.48 to 1.75), and the authors reported the association was constant over time. Suicide was not significantly associated with finasteride (HR 1.22, 0.99 to 1.49) or with dutasteride (HR 0.98, 0.62 to 1.54) [4].

The available cohort evidence comes mainly from older men treated for prostate enlargement, so it does not directly establish the effect in young men taking 1 mg for hair loss. Both studies drew on prescription and diagnosis records, so a depression outcome means a recorded diagnosis rather than a mood score [3][4].

Smaller and report-based studies

Irwig 2012 compared 61 former users who had persistent sexual side effects for three months or more with 29 men who had hair loss and had never used finasteride. Depressive symptoms (a Beck Depression Inventory II score of 14 or more) were present in 75% (46 of 61) versus 10% (3 of 29), P<0.0001. The study was small, self-selected and cross-sectional, so it cannot show cause [6].

Irwig 2011 used standardized interviews with 71 otherwise healthy men aged 21 to 46 who reported new sexual side effects lasting at least three months after stopping finasteride. Mean finasteride use was 28 months and mean persistence 40 months. The design was post hoc and vulnerable to recall bias, so it cannot supply a frequency [7].

Melcangi 2013 measured neuroactive steroids in cerebrospinal fluid and plasma from three post-finasteride patients and five healthy controls. CSF levels of tetrahydroprogesterone, isopregnanolone and DHT were decreased, and testosterone and 17-beta-estradiol were increased [8]. Three patients is a signal, not a rate.

A pharmacovigilance analysis of the WHO VigiBase database counted 356 suicidality reports and 2,926 reports of psychological adverse events in finasteride users, most of those with age data aged 18 to 44. It found disproportionality signals for suicidality (reporting odds ratio 1.63, 95% CI 1.47 to 1.81) and psychological adverse events (4.33, 4.17 to 4.49), with higher suicidality signals in younger patients (3.47, 2.90 to 4.15) and in those with alopecia (2.06, 1.81 to 2.34) [12]. Reporting odds ratios from spontaneous reports show that an event is reported disproportionately often, not how common it is or whether finasteride caused it.

Why the enzyme might affect mood

Finasteride is a competitive inhibitor of Type II 5-alpha reductase, the enzyme that converts testosterone to DHT. The Type II enzyme accounts for about two-thirds of circulating DHT, and finasteride is roughly 100-fold selective for it over Type I. A 1 mg tablet suppresses serum DHT by 65% within 24 hours. Mean testosterone and estradiol rise by about 15% but stay within the normal range, and finasteride has no affinity for the androgen receptor [5].

The same enzyme family reduces progesterone and deoxycorticosterone to dihydroprogesterone and dihydrodeoxycorticosterone. Their 3-alpha-reduced metabolites enhance GABA-A inhibitory neurotransmission and show anticonvulsant, antidepressant and anxiolytic effects in preclinical work [9]. That is a proposed route from the drug to mood; the cohort studies measured diagnoses, not neurosteroid levels.

Sexual side effects and mood symptoms

In three 12-month controlled trials of 1 mg finasteride (945 men on drug, 934 on placebo), drug-related decreased libido was 1.8% versus 1.3%, erectile dysfunction 1.3% versus 0.7%, and ejaculation disorder 1.2% versus 0.7%. One or more of these was reported by 3.8% versus 2.1% on placebo (p=0.04), and the incidence of each fell to 0.3% or lower by year 5 [5]. A self-administered sexual function questionnaire at month 12 favored placebo in three of four domains: sexual interest, erections, and perception of sexual problems [5].

A 2019 meta-analysis of 15 randomized placebo-controlled trials (4,495 men with androgenetic alopecia) found a relative risk of sexual dysfunction of 1.57 (95% CI 1.19 to 2.08) for 5-alpha reductase inhibitors, and 1.66 (1.20 to 2.30) for finasteride alone [10]. A separate meta-analysis of 34 finasteride trials for hair loss found that none had adequate safety reporting and that 76% evaluated safety for one year or less [11].

The label also lists sexual dysfunction that continued after discontinuation of treatment, including erectile dysfunction, libido disorders, ejaculation disorders and orgasm disorders [5]. These studies did not test whether mood symptoms follow sexual ones.

What remains uncertain

The Propecia label's 12-month trial table lists drug-related sexual adverse experiences; depression appears only among postmarketing reports, which carry no incidence figure [5]. A meta-analysis of 34 finasteride trials for androgenetic alopecia found none had adequate safety reporting [11].