cialis is spose to last 36 hrs +.. viagra is about 4-5 .. I've used both.. Viagra is good for the bar if you get to hammered .. You can mix with drinks.. Cialis feels more natural, but If u take with drinks u get a bad hangover .. so depends on the situation.. cialis gives me a feeling like i have a stuffed up nose.. goes away the next day .. this is off the pharm name brand ones.. not liquid.