Without going into details perhaps it would be helpful and informative to relate my brief experience with Viagra. By now most people have heard of the 6 who died so far. They also took either before, during, or after the Viagra some form of Nitro..which expands the heart's arteries and lowers the blood pressure. Viagra also lowers the blood pressure among other things. My particular condition includes Parkinson's, Edema of both legs, and impotence as a result of prostate surgery. In some cases like mine Viagra does assist. First trial was at 25mg - very cautious. My wife and I tried various forms of stimulation, but the result was inadequate - only partial erection. I felt a little dizzy about an hour after taking the pill. I discontinued Imdur (a nitro) before the first attempt. The second time, days later, I took 50mg, but the result was not much better. My medical condition probably puts me in the 20% or so who have an erection problem for whom Viagra is not effective.