If a healthcare professional has prescribed tadalafil 40 mg (such as Vidalista 40) for you, the timing depends on why it was prescribed and the instructions you were given. For erectile dysfunction, tadalafil is commonly taken: About 30 minutes to 1 hour before sexual activity. It may remain effective for up to 36 hours, so it does not need to be taken immediately before sex. It is usually taken once per day at most. For other conditions, such as Pulmonary Arterial Hypertension, tadalafil may be prescribed on a regular daily schedule  Vidalista 40. A few important points: Follow the exact dose and schedule your prescriber recommended. Avoid taking more than prescribed or taking multiple doses in a 24-hour period unless specifically instructed. Do not use tadalafil with nitrate medications because of the risk of a dangerous drop in blood pressure. Alcohol can increase the risk of dizziness and low blood pressure. If you tell me: Your age, Whether the prescription is for erectile dysfunction or another condition, Whether this is your first time taking tadalafil, I can explain the typical timing and what to expect.