I am 69, and have been taking Cialis 20mg on average about once or twice a month for the past eight years. I had a heart by-pass in 2003 ( I was lucky, I never had a heart attack, the need for a by-pass was found before that could happen). Recently - over the last four months or so, I have found it difficult to sustain an erection or get a sufficient degree of hardness to achieve penetration. The only medication I take daily is Losartan Potassium 50mg to control blood pressure, and Simvastatin 40mg to control Cholesterol, plus 1 -75mg dispersible Aspirin. I have never tried any other impotence treating drugs than Cialis. I am in good general health, not overweight, a non smoker, and take regular exercise.