Zhewitra 40 mg (which contains vardenafil) is taken before sex because it is an “on‑demand” erectile‑dysfunction (ED) medicine that needs time to work in the body and only acts when there is sexual stimulation. How it works Zhewitra 40 mg is a PDE5 inhibitor (same class as Levitra/Vardenafil) that relaxes the smooth muscles in the penis and increases blood flow, helping you get and keep an erection when you are sexually aroused. It does not cause an automatic erection; it only enhances the natural response to sexual stimulation.Zhewitra 40 mg  before sex? The usual advice is to take one 40 mg tablet about 30–60 minutes before planned sexual activity, so the drug reaches effective levels in your bloodstream by the time you have intercourse. Taking it with a full glass of water and avoiding a heavy, high‑fat meal around that time can help the medicine work faster and more reliably. Safety and precautions Zhewitra 40 mg is a strong dose and should only be used if prescribed by a doctor, especially if you have heart disease, low blood pressure, or take nitrates (for chest pain), because combining them can be dangerous.