Cenforce is the most prescribed drug for the treatment of male erectile dysfunction. Sildenafil stimulates blood circulation near the penis during sexual arousal which results in an erection. Cenforce works half an hour after use so it should be taken half an hour before planned sexual activity. You can take this medicine before or after food. The effect of this medicine lasts for 4 to 6 hours. This medicine is only taken by men aged 18 to 65 years. Take this medicine as per your doctor's advice.