Cenforce can increase erection firmness and help you maintain an erection, provided erection difficulties are related to erectile dysfunction. How Cenforce works Cenforce contains sildenafil citrate, the same active ingredient found in Viagra. It works by: Increasing blood flow to the penis. Helping you achieve a harder, firmer erection when sexually stimulated. Helping maintain an erection during sexual activity. Reducing the likelihood of losing an erection too quickly. How long does it work? Onset: Usually 30–60 minutes. Cenforce Around 4–5 hours. Important: It doesn't cause a continuous erection; sexual stimulation is still necessary. Important precautions Never combine it with nitrate medications (for chest pain) or riociguat. Avoid combining it with other erectile dysfunction medicines. Common side effects include headache, flushing, nasal congestion and indigestion. An erection lasting more than 4 hours requires emergency medical attention. A question to understand your situation Are you experiencing: Erection happens but isn't hard enough. Erection is initially hard but becomes soft during sex. Erection is hard during masturbation but less firm during intercourse. Erection is firm but you want even greater hardness. Your answer will help me explain whether Cenforce is likely to help.