Description

Propecia (finasteride 1 mg)

Propecia contains 1 mg of finasteride and is indicated for male-pattern hair loss (androgenetic alopecia) in men. It works by inhibiting 5-alpha reductase type 2, the enzyme that converts testosterone to dihydrotestosterone (DHT) in hair follicles. DHT is the principal driver of follicle miniaturization in androgenetic alopecia; reducing it slows hair loss and, in many men, produces some regrowth over 12 to 24 months of treatment.

Dosing

One 1 mg tablet daily, taken consistently. Results require daily use — missing doses or stopping treatment reverses the benefit. The maximum benefit is typically seen over the first two years; clinical studies confirm efficacy primarily in men aged 18 to 41. Taking the tablet with food can reduce the likelihood of gastrointestinal effects.

Hair regrowth or loss stabilization requires months of continued treatment. The effect is not permanent — stopping finasteride results in progressive reversal of any gains within 12 months.

Contraindications

Women and children must not use finasteride. Women of childbearing age must not handle crushed or broken tablets — finasteride is absorbed through skin and causes abnormal development of male fetal genitalia. Finasteride is absolutely contraindicated during pregnancy. Patients with liver disease or renal impairment should not use it without medical guidance.

PSA and cancer risk

Finasteride reduces PSA levels by approximately 50% after 6 months. Any prescriber ordering a PSA test needs to know the patient is taking finasteride to interpret the result correctly. Clinical trials found finasteride reduced overall prostate cancer incidence but was associated with a higher proportion of high-grade tumors in men who did develop cancer — the significance of this finding remains debated.

Sexual side effects

Decreased libido, erectile dysfunction, and reduced ejaculate volume were reported in approximately 3 to 4% of men in controlled trials, compared to about 2% in placebo groups. The FDA updated the Propecia label in 2012 to include a warning that sexual side effects — including decreased libido, erectile dysfunction, and ejaculation disorders — may persist after stopping treatment in some men. This is not universal, but patients should be aware before starting long-term therapy.

Side effects

Beyond sexual effects, clinical data shows finasteride is generally well-tolerated at 1 mg. Breast tenderness or enlargement has been reported. Hypersensitivity reactions including rash and urticaria are uncommon.