The active ingredient in the medication Fildena is sildenafil citrate. The primary target patient population for this medicine is men with erectile dysfunction (ED). By boosting blood flow to the penis, sildenafil citrate, an inhibitor of phosphodiesterase type 5 (PDE5), helps men get and maintain an erection when they are sexually aroused. Headaches, flushing, upset stomach, and vertigo are possible adverse effects. In addition, there might be anomalies in the eyes, such as increased sensitivity to light, blurred vision, or trouble telling the difference between the colors blue and green. Fildena side effects any of these adverse effects get worse or continue, let your doctor or pharmacist know as soon as possible. Take it slowly when rising from a sitting or lying position to reduce the likelihood of feeling lightheaded and dizzy.