Fildena 50 contains sildenafil citrate, a medication used to treat erectile dysfunction (ED). While many people use it safely under medical guidance, some situations require stopping the medication immediately and seeking medical attention. You should stop using Fildena 50 and get urgent medical care if you experience: Chest pain during or after sexual activity. An erection lasting longer than 4 hours (priapism), which can cause permanent damage if not treated promptly. Sudden loss of vision in one or both eyes. Sudden hearing Fildena 50 or ringing in the ears, especially if accompanied by dizziness. Signs of a severe allergic reaction, such as swelling of the face, lips, tongue, or throat, difficulty breathing, or widespread rash. You should also not continue taking Fildena 50 if you begin using nitrate medications (commonly prescribed for chest pain), as combining nitrates with sildenafil can cause a dangerous drop in blood pressure. If you develop severe dizziness, fainting, irregular heartbeat, or any other serious side effects after taking Fildena 50, stop using it and contact a healthcare professional promptly.