 In certain circumstances in which the males are young, no comorbidities are recognized, and laboratory tests are normal, one should look for the underlying cause of their erectile dysfunction before instituting treatment since the disease process may be more serious than the ED itself.In some cases, treatment of the underlying cause may resolve the sexual dysfunction.Particular caution should be used when prescribing PDE5 inhibitors for erectile dysfunction for patients receiving protease inhibitors, including Reyataz.