Vidalista 40mg is a pill containing generic tadalafil that helps treat erectile dysfunction. It works by inhibiting PDE-5 enzymes, increasing cGMP levels which improves blood flow to the penis during sexual stimulation. It should be taken about one hour before sex and its effects last up to 36 hours. Possible side effects include headache, upset stomach, and vision or hearing changes. Safety precautions include avoiding alcohol and grapefruit when taking it and not driving or operating machinery after use until its effects are known.