The active effect of Cenforce 100 is usually two to three hours. However, this may vary depending on various factors, including the type of medication and individual. The effects of Sildenafil usually begin within 30 minutes to an hour after consumption and may last for up to two hours. The different strengths of Cenforce are identified by the chemical component that is present in one unit dose. These strengths are different enough to give varying results for different patients.