Finasteride Appetite & Cravings Changes: What the Evidence Actually Shows

Does finasteride change appetite?

Neither the 1 mg nor the 5 mg label lists appetite change or cravings as an adverse reaction [1][2]. What the labels do list, drawn from the trials, is a small cluster of sexual effects.

The 1 mg label reports three 12-month controlled trials: decreased libido in 1.8% versus 1.3% on placebo, erectile dysfunction in 1.3% versus 0.7%, and ejaculation disorder in 1.2% versus 0.7%. Overall, 3.8% of men on finasteride (36 of 945) reported one or more of these versus 2.1% on placebo (20 of 934) [1].

The 5 mg label reports the four-year PLESS study of 3,040 men with BPH. In year one, impotence was 8.1% versus 3.7% on placebo, decreased libido 6.4% versus 3.4%, decreased ejaculate volume 3.7% versus 0.8%, breast enlargement 0.5% versus 0.1%, breast tenderness 0.4% versus 0.1% and rash 0.5% versus 0.2%. In years two to four there was no significant difference between groups in impotence, decreased libido or ejaculation disorder [2].

What the trials actually recorded

These were hair-growth and prostate-symptom trials, not metabolic studies. In the two vertex baldness trials, a self-administered sexual function questionnaire at month 12 showed statistically significant differences in favor of placebo in three of four domains: sexual interest, erections and perception of sexual problems [1].

Adverse-event capture in this literature was limited. A meta-analysis of 34 finasteride trials for hair loss found that none had adequate safety reporting, 19 were partially adequate and 12 inadequate, and funnel plots suggested systematic under-detection of sexual adverse effects [3].

What the postmarketing lists add

Both labels also carry postmarketing reports, meaning events reported after approval rather than seen in the trials: hypersensitivity reactions, testicular pain, hematospermia, breast tenderness and enlargement, male breast cancer, depression, suicidal ideation and behavior, and sexual dysfunction that continued after stopping treatment [1]. These reports are voluntary, so their frequency and whether finasteride caused them cannot reliably be determined [1][2].

What finasteride does change

Finasteride blocks Type II 5-alpha-reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT). A 1 mg tablet reaches about 65% suppression of serum DHT within 24 hours, mean circulating testosterone and estradiol rise by about 15% but stay within the normal range, and finasteride has no affinity for the androgen receptor [1].

Food is a separate matter. Bioavailability is about 65% and is not affected by food, and the label states the tablet can be taken with or without meals [1].

Reporting a suspected reaction

The Propecia label lists FDA MedWatch (1-800-FDA-1088 or www.fda.gov/medwatch) and the manufacturer Organon (1-844-674-3200) for reporting suspected adverse reactions [1].