I realize  that Cialis lasts  up to  36 hours, Viagra about 2 to 4,   I am not certain about Levitra.
I have tried  Viagra, and   I find not much difference between my normal  erections,and supposedly "enhanced "erections, except that  the major "enhancements" are a headache (Aspirin helps) , And a  stufffy nose. I recently was given  a free medical sample of Cialis, and tried it, and it seemed to work better than Viagra.(Even woke up with my  old teenagestyle "Stiffy!). Still got the  Headache  and stuffy nose, but only for an hour or so. Have yet to try Cialis. Any new, or  old  views on   effectiveness side effects, stiffy factor etc, would be appreciated no matter  whether    used as recreational, or as a necessity.