The most common side effect of clonazepam is drowsiness. For both men and women Klonopin will often decrease their libido and sex drive making sex seem. Jump to Side Effects of Clonazepam - There are a number of side effects of clonazepam, especially if you take it for a long period of time or at high. The Truth About Klonopin And Its Side Effects. Klonopin is an useful Apart from this, Klonopin is also known to cause impotence in men. When this happens.