Fildena 50 is a brand name for a medication containing the active ingredient Sildenafil, which is a phosphodiesterase type 5 (PDE5) inhibitor. Like other medications containing Sildenafil, Fildena 50 is primarily prescribed to treat erectile dysfunction (ED) in men. Sildenafil works by increasing blood flow to the penis when a man is sexually aroused. This helps in achieving and maintaining an erection.