The side effects of Propecia were uncommon and did not affect most men. However, it would be prudent to take a look at them, in case you experience side effects.
**UPDATE** In the March 2011 issue of the Journal of Sexual Medicine, doctors explain the results of their study regarding sexual side effects and Propecia use. About 8% of the men in this study reported suffering from erectile dysfunction. While in the past sexual side effects seemed less commonplace, researchers are looking into this more carefully.
The upside for this downside, however, is that they say the drug Flomax could help improve sexual function for men taking Propecia. The authors of this article emphasize that this is in no way saying Propecia could cause permanent damage to a man’s sexual health, however, they do concede that long term studies have not been done yet.
Allergic Reaction: If you have an allergic reaction to Propecia, you might have itching, a rash, and hives. Your lips and face might swell and eventually, your throat could close. This is a standard allergic reaction and you should immediately seek medical attention.
Sexual Side Effects I: You could experience problems with ejaculation or pain in your testicles. You might experience breast tenderness and enlargement. Of course, if you have any of these effects, seek medical attention immediately.
Sexual Side Effects II: You might experience a decrease in your desire for sex, problems in getting an erection, and a decrease in the amount of ejaculate or semen.