I have had ed for probably 8 yrs or so..When I tried Viagra the first couple times it worked fine but after a few times it now seems I get a decent erection but when I go to perform down it goes..I have used injections and almost the same results although the poking thought turned me off..I have used the 25 50 and 100 sizes and the 25 does as good as the 100..It seems as soon as wife starts stimulation things go the wrong way..Really wish I could get help as still lots of libido..