My experience on these products:
Viagra - Lasts about 5 hours, headache
Cialis - Lasts around 36 hours, dry around the eyes and blurred
vision
Try these alternatives, I find them to be better:
Vigour Gold 300 - Lasts about 4 days, no side effects
Magna RX Supreme - Lasts about 6 days, increased penis size, no
side effects
Legendary India Magic Oil - Spray on only, Lasts about 10 hours,
increase penis size, remove premature ejaculation and effectively
prolongs erection and ejaculation, no side effects