Fildena Professional is a medication used to treat erectile dysfunction (ED) in men. It contains the active ingredient sildenafil citrate, which helps increase blood flow to the penis to achieve and maintain an erection. Common side effects may include headaches, flushing, indigestion, nasal congestion, and dizziness. Rare but serious side effects include sudden vision loss or an erection lasting more than 4 hours (priapism).