Several Parallels have been drawn between Viagra and Cialis. Both help solve erectile issues. Both help in improving endurance levels for athletes in order to help them last through their workout sessions. However the similarities end there. Firstly Cialis can be effective for 24-36 hours which is 4-6 times the endurance of Viagra. Moreover this drug can also be used for Post Cycle Treatment as it helps push back testosterone levels when steroid cycles are stopped. This drug pushes testosterone levels for long periods of time thus helping prevent muscle mass loss. Hence it is more effective and one can say more useful than Viagra.