• Before you start finasteride, your healthcare provider should make sure your enlarged prostate symptoms are not caused by another condition, such as prostate cancer or bladder problems.
   
• Men with severely decreased urine flow or men who can only empty very little of their bladder at a time should be closely monitored by their healthcare providers. For these men, finasteride may not be the best option.
   
• Finasteride does not prevent prostate cancer. Men can have both BPH and prostate cancer at the same time.
   
• Finasteride can lower your PSA levels. The PSA (prostate specific antigen) blood test is a common way to screen for prostate cancer (see Prostate Cancer Screening). Your healthcare provider will need to adjust your PSA test result (by doubling it) if you are taking finasteride. Your healthcare provider can also use a slightly different blood test (the "percent free PSA" test) that does not need to be adjusted.
   
• Finasteride can cause sexual side effects, including decreased libido (sex drive), erectile dysfunction (ED or impotence), and decreased ejaculation amount. Usually, decreased ejaculation amount does not interfere with sexual function (see Proscar Sexual Side Effects for more information).
   

• Are allergic to finasteride, Proscar, Propecia, or any inactive component used to make the medicine. Your healthcare provider or pharmacist has a list of the inactive ingredients.
   
• Are or may be pregnant.