Does finasteride (Propecia)/minoxidil (Rogaine) cause gynecomastia?

From the Guidelines

Finasteride may potentially cause gynecomastia as a side effect, while minoxidil typically does not. Finasteride works by inhibiting the enzyme 5-alpha reductase, which reduces dihydrotestosterone (DHT) levels. This hormonal change can sometimes lead to an imbalance between testosterone and estrogen, potentially causing breast tissue enlargement in men.

Key Points to Consider

• The risk of gynecomastia with finasteride is relatively low, occurring in approximately 1-2% of users, and is more common with the 5mg dose used for prostate conditions than the 1mg dose used for hair loss 1.
• Minoxidil, on the other hand, works as a vasodilator that stimulates hair follicles directly and doesn't affect hormone levels, so it rarely causes gynecomastia.
• If you notice breast tenderness, swelling, or enlargement while taking finasteride, you should consult your healthcare provider promptly. They may recommend discontinuing the medication or adjusting the dosage.
• Some users find that the risk of side effects decreases over time with continued use, but this varies between individuals.

Evidence from Studies

• A study published in the Journal of Clinical Oncology found that finasteride increased the risk of gynecomastia, with a relative risk of 2.13 (95% CI, 1.15 to 3.95) compared to placebo 1.
• Another study published in The Journal of Urology found that the risk of gynecomastia with finasteride was approximately 2-4% higher than with placebo 1.
• A review of the evidence by the American Society of Clinical Oncology and the American Urological Association found that finasteride was associated with a small but significant increase in the risk of gynecomastia 1.

From the FDA Drug Label

Breast Enlargement 0.5 0.1 1.8 1.1 Breast Tenderness 0.4 0.1 0.7 0.3 Gynecomastia 0.7 1.1 2.2 1.5

Gynecomastia is reported as an adverse experience in the finasteride clinical trials. The incidence of gynecomastia was 2.2% in the finasteride group, 1.1% in the doxazosin group, and 0.7% in the placebo group in the MTOPS study. In the 4-Year Placebo-Controlled Study, the incidence of breast enlargement was 0.5% in the finasteride group and 0.1% in the placebo group in year 1, and 1.8% in the finasteride group and 1.1% in the placebo group in years 2 to 4. The incidence of breast tenderness was 0.4% in the finasteride group and 0.1% in the placebo group in year 1, and 0.7% in the finasteride group and 0.3% in the placebo group in years 2 to 4 2.

From the Research

Finasteride and Gynecomastia

• Finasteride has been reported to cause gynecomastia in some cases, as seen in a study published in the International Journal of Trichology in 2009 3.
• This study presented two cases of gynecomastia, one of which was bilateral, caused by finasteride prescribed for the treatment of androgenetic alopecia.
• Although gynecomastia is a relatively rare side effect of finasteride, physicians should be aware of it and inform their patients when prescribing this medication.

Minoxidil and Gynecomastia

• There is no direct evidence in the provided studies that minoxidil causes gynecomastia.
• However, a study published in Toxicology and Applied Pharmacology in 2023 compared the effects of finasteride and minoxidil on male reproductive organs and found that both medications can act as hormone disruptors, causing oxidative stress and morphological changes mainly in the testis 4.
• Another study published in The Journal of Dermatological Treatment in 2022 discussed the use of oral minoxidil for treating androgenetic alopecia, but did not mention gynecomastia as a side effect 5.

Combination Therapy and Gynecomastia

• A systematic review and meta-analysis published in Dermatologic Therapy in 2020 evaluated the effectiveness of combination therapies for androgenetic alopecia, including minoxidil with finasteride, but did not discuss gynecomastia as a side effect of these combination therapies 6.
• The study found that combination therapy could be an effective and safe option for treating androgenetic alopecia, but more research is needed to confirm the efficacy of combined treatment.