How Does Cialis Work?
Cialis (tadalafil) is a PDE5 inhibitor that helps relax blood vessels in the penis during sexual stimulation. Its longer half-life means effects can last up to about 36 hours for as-needed use — longer than typical sildenafil. Arousal is still required.
Written by Virantus Editorial Team
Medically reviewed by Virantus Clinical Team · Reviewed August 2026
Last updated August 2026
The mechanism
Tadalafil works similarly to sildenafil — it blocks PDE5 to support blood flow during sexual stimulation. The key difference is pharmacokinetics: tadalafil stays in the body longer, which is why some men describe a longer window of opportunity.
A longer window is not a 36-hour erection. It means the medicine may still support erections with stimulation later in that period.
Daily vs as-needed
As-needed tadalafil is taken before anticipated sexual activity. Daily tadalafil uses a lower dose on a regular schedule for men who prefer not to time a pill around sex, when a clinician decides that is appropriate.
These are different regimens with different strengths. Do not convert one into the other without medical guidance.
Food and timing
Tadalafil is generally less affected by food than sildenafil for many men. Onset for as-needed use is often in a similar ballpark (about 30–60 minutes), though individual response varies.
A clinician helps you choose timing that fits your plans and health.
Common questions
Sources
Related guides
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