Short answer: In the label's three 12-month hair loss trials, the most common Propecia side effects were sexual: decreased libido (1.8% vs 1.3% on placebo), erectile dysfunction (1.3% vs 0.7%) and ejaculation disorder (1.2% vs 0.7%). Overall, 3.8% of men on Propecia reported one or more of these vs 2.1% on placebo. The label also covers PSA changes and prostate cancer. There is no boxed warning.
What Propecia is approved for: Propecia is a 5α-reductase inhibitor approved for male pattern hair loss (androgenetic alopecia) in men only. The label says efficacy for receding hair at the temples has not been established, and it is not for use in women or children (section 1).
Source
PROPECIA (finasteride) tablets, for oral use, prescribing information and Patient Information. Organon. DailyMed, version published October 14, 2024. DailyMed setid 6f904709-65aa-44ce-b144-b4c8a0416e36
No. The current Propecia label has no boxed warning.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Propecia.
| Adverse experience | Propecia N=945 | Placebo N=934 |
|---|---|---|
| Decreased Libido | 1.8 | 1.3 |
| Erectile Dysfunction | 1.3 | 0.7 |
| Ejaculation Disorder (Decreased Volume of Ejaculate) | 1.2 (0.8) | 0.7 (0.4) |
| Discontinuation due to drug-related sexual adverse experiences | 1.2 | 0.9 |
Three controlled 12-month trials in men with male pattern hair loss. Only events the investigators judged possibly, probably or definitely drug-related, at 1% or more, are listed. The figure in brackets is decreased volume of ejaculate.
36 of 945 men (3.8%) on Propecia reported one or more of these sexual side effects vs 20 of 934 (2.1%) on placebo. They resolved in men who stopped Propecia and in most who kept taking it, and each fell to 0.3% or less by the fifth year.
In healthy men on finasteride 1 mg daily for 48 weeks, ejaculate volume fell a median 0.3 mL (-11%) vs 0.2 mL (-8%) on placebo.
In a sexual function questionnaire at month 12, placebo was favored in 3 of 4 areas (sexual interest, erections and perception of sexual problems), with no difference in overall satisfaction with sex life. Breast tenderness or enlargement, allergic reactions and testicular pain were no different from placebo.
In men aged 18 to 41 on Propecia, mean PSA fell from 0.7 ng/mL to 0.5 ng/mL at month 12.
Reported after approval: allergic reactions including swelling of the lips, tongue, throat and face; sexual problems that continued after stopping, including erectile, libido, ejaculation and orgasm disorders; male infertility or poor semen quality; testicular pain; blood in semen; male breast cancer; breast tenderness and enlargement; depression; and suicidal thoughts and behavior.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Risk to a male fetus. Propecia is not for women. Women who are or may be pregnant should not handle crushed or broken tablets, because absorbed finasteride could harm a male fetus. Whole coated tablets prevent contact during normal handling.
Lower PSA readings. Propecia lowers the prostate cancer screening test PSA. Any confirmed rise from the lowest PSA value on Propecia may signal prostate cancer and is evaluated, even if it is still in the normal range. Missed doses can also affect PSA results.
High-grade prostate cancer. In a 7-year trial of men 55 and older, finasteride 5 mg a day (5 times the Propecia dose) was linked to more Gleason 8-10 prostate cancer: 1.8% vs 1.1% on placebo. 5α-reductase inhibitors may raise the risk of high-grade prostate cancer.
Children. Propecia is not approved for children.
Who should not use it. Women who are or may become pregnant, and anyone allergic to any component of the tablet.
From the Patient Information leaflet that comes with Propecia:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.