Fildena is a brand name for a medication that is primarily used to treat erectile dysfunction (ED). The active ingredient in Fildena is Sildenafil Citrate, the same active ingredient found in well-known medications like Viagra. Sildenafil works by increasing blood flow to the penis, helping men with erectile dysfunction achieve and maintain an erection during sexual activity. Sildenafil Citrate (the active ingredient) works by inhibiting the PDE5 enzyme that breaks down cGMP (a substance that helps the blood vessels in the penis relax). https://www.genericday.com/fildena.html