Cialis (tadalafil) differs from Viagra (sildenafil).
Cialis contains the active ingredient tadalafil, which is a PDE5 inhibitor. While medication effects of sildenafil citrate-containing drugs typically last up to 6–8 hours, the effects of Cialis and tadalafil last for 24–36 hours.
Additionally, while sildenafil citrate-containing drugs should be taken on an empty stomach, Cialis and tadalafil absorption is not affected by food. Therefore, the medications can be taken with or without food.
This information is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment, and should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your healthcare provider.