Cialis lasts up to 36 hours, Viagra lasts 4 to 6. Cialis is unaffected by food, Viagra is significantly reduced by fatty meals. Cialis can be taken daily, Viagra cannot. This head-to-head comparison covers all 7 key differences, a full comparison table, who should choose which, and the cost of genuine generics Cenforce and Vidalista at TheMedicineKart.