Generic Cialis starts working faster than generic Viagra, sometimes in 16 minutes, and lasts 24 hours or more. In contrast, Canadian Viagra usually works for only four hours after an hour’s delay.

As with Viagra, 80% of men with erectile function are able to achieve an erection with Cialis drug use and three out of four are able to achieve sexual intercourse. But in one Cialis study, 59% of previously impotent men were still able to have sex 36 hours after taking it.

The reason is that the body takes four times as long to get rid of Cialis (tadalafil) than to eliminate Viagra. The half-life of Viagra (time for blood levels to fall 50%) is 4 hours compared to 17 hours for canadian Cialis. That means 25% of a Cialis dose is still present in the body after 35 hours, and 12.5% after more than 50 hours. It also means that Cialis (tadalafil) will accumulate in the body if taken regularly.