Valtrex (valaciclovir hydrochloride) is an antiviral medication that is used to treat certain infections caused by the herpes virus (shingles, cold sores, chickenpox, and genital herpes). As with all medicines, Valtrex has possible side effects. However, sexual side effects have not been reported, either before or after clinical studies were conducted. If a person does develop sexual side effects, such as impotence or a decrease in libido, it is difficult to know whether these problems are caused by another condition or by Valtrex itself.

Before medicines are approved, they must go through several clinical studies, where thousands of people are given a particular medicine and are then compared to a group of people not given the medicine. In these studies, side effects are always documented. As a result, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine. Side effects are then usually separated into those that occur in more than 1 percent of people and those that occur in less than 1 percent of people. Sexual side effects, such as a decrease in sex drive (libido) or impotence, were not reported as either a common or rare side effect with Valtrex during these studies.

It is impossible for your healthcare provider to know whether you will develop any sexual side effects while taking Valtrex. Also, if sexual side effects do occur, such as impotence or a decrease in libido, it is difficult to know whether these problems are caused by another condition or by Valtrex.