It's important to be aware that most men that take finasteride don't have any side effects. However the following may occur in a low proportion of users
a) Sexual dysfunction. Decreased libido (sex drive) and impotence occur in approximately 1-4 % of men.
- In the majority of patients who were studied in clinical trials, these sexual issues improved over time even in men who continued the drug. Nevertheless, Dr. Donovan recommends stopping the drug if these problems occur. Recently there have been increasing reports of men who developed persistent sexual dysfunction even after stopping finasteride. This warning has now been included on the drug label. At present, it is not known just how common of a side effect this is, but it is important for all men on the drug to be aware of this.
b) Mood changes (lowered mood, depression & anxiety) in 1:100 men
c) Enlargement of breast tissue in men (a phenomenon called 'gynecomastia') - thought to be less than 1:200
d) Testicular pain