I have ben on finasteride for 6 months now and just started to note sexual side efect (ED). What can I do?

The sexual side effects from finasteride can appear at any time. It may be caused by the drug. See your doctor and discuss this with him. I generally tell my patients to reduce the dose to one pill every 4th day for 3 weeks, then one pill every 3 days for 3 weeks and then end up with one pill every two days and stay on the lower dose if that dose helps the side effects.