Fildena 50 is a medication commonly used to treat erectile dysfunction (ED) in men. It is a generic version of Viagra and contains the active ingredient sildenafil citrate, which is a phosphodiesterase type 5 (PDE5) inhibitor. The effects of Fildena 50 generally last for about 4 to 6 hours, during which a man may find it easier to achieve and sustain an erection.