d. pearson,   Thanks for your question.    The answer is yes; simvastatin, as well as other statin medication can affect a person's libido.   A Dutch study evaluated patients with decreased libido who were taking statin medication.  Some of the patients were found to have lower testosterone levels.  It is believed that statins can also reduce the production of testosterone.  In all cases, the effect was reversible when the statin medication was discontinued.   I suggest you discuss this with your physician.  He might want to try another statin, because not all drugs may cause the same side effects.  Other options include medications in another class, such as Zetia and Niaspan.  Have you tried your best with diet restriction alone?  If not, this may be an option as a trial before starting a new medication.   I hope this has been helpful.  Best wishes.   Martin Cane, M.D.