From the Guidelines
Finasteride does not typically cause penile shrinkage, and its use is generally safe with minimal risk of severe side effects. Finasteride is a medication used to treat male pattern baldness and enlarged prostate by blocking the conversion of testosterone to dihydrotestosterone (DHT) 1. While some men may experience sexual side effects like decreased libido or erectile dysfunction, actual physical shrinkage of the penis is not a known or common side effect. The standard dose for hair loss is 1 mg daily, while 5 mg daily is used for prostate issues.
Key Points to Consider
- Sexual side effects occur in a small percentage of users and usually resolve if the medication is stopped 1.
- Finasteride has been shown to reduce prostate volume by 15-25% at six months, with atrophy most pronounced in the glandular epithelial component of the prostate 1.
- When providers are screening men for prostate cancer who are on 5-ARIs, patients should be informed of alterations in PSA due to the medication, and the measured serum PSA value should be doubled to accurately gauge disease progression after 1 year of 5-ARI therapy 1.
- Treatment with 5-ARIs and combination therapy hinges on prostate volume and PSA threshold, and obtaining imaging with TRUS to objectively assess prostate size is reasonable, with reservation of 5-ARIs for those with appropriately enlarged glands 1.
Recommendation
If you're concerned about potential side effects, discuss them with your doctor before starting treatment. They can help weigh the benefits against any risks for your individual situation. Remember that many men take finasteride without experiencing significant adverse effects, and the medication has been shown to improve standardized symptom scores and reduce clinical progression in men with enlarged prostates 1.
From the Research
Finasteride and Penile Shrinkage
- There is no direct evidence in the provided studies to suggest that finasteride causes penile shrinkage 2, 3, 4, 5, 6.
- The studies primarily focus on the effects of finasteride on sexual dysfunction, prostate cancer, and benign prostatic hyperplasia, but do not mention penile shrinkage as a potential side effect.
- Finasteride has been associated with sexual side effects such as decreased libido, ejaculation disorders, and impotence, but these effects are not directly related to penile shrinkage 4, 5.
- One study suggests that finasteride may cause persistent sexual side effects, including changes in genital sensation, but does not specifically mention penile shrinkage 5.
Sexual Dysfunction and Finasteride
- Finasteride has been linked to sexual dysfunction, including erectile dysfunction, decreased libido, and ejaculation disorders 2, 3, 4, 5.
- The severity and persistence of these side effects are still debated, with some studies suggesting that they may be permanent 5.
- Physicians should discuss the potential long-term effects of finasteride on sexual function with their patients, although the evidence is not conclusive 3.
Prostate Cancer and Finasteride
- Finasteride has been shown to reduce the incidence of low-grade prostate cancer, but its effect on high-grade prostate cancer is still unclear 2, 6.
- The medication can decrease serum levels of prostate-specific antigen (PSA), which may affect the detection of prostate cancer 6.
- Physicians should be aware of the potential effects of finasteride on PSA levels and monitor patients accordingly 6.