Tadfil 20 mg contains tadalafil. After taking it by mouth, tadalafil is absorbed relatively quickly: Absorption begins: the drug starts entering the bloodstream within the first few hours after taking it. Peak blood concentration: typically reached in about 2 hours (median), although this varies between people. When it starts working: many people notice effects within 30–60 minutes, but it can take longer. Duration: tadalafil can remain effective for up to 36 hours. A high-fat meal generally does not significantly change tadalafil absorption, unlike sildenafil, although individual response can vary. If you're asking because you just took Tadfil 20 mg and want to know when it's safe/effective to have sex, tell me approximately when you took it and whether you took it with food or alcohol.