Fildena CT 50 mg contains sildenafil 50 mg, a PDE-5 inhibitor. It affects blood flow because sildenafil changes how the blood vessels relax. During sexual stimulation, your body releases nitric oxide (NO), which increases a chemical called cGMP. cGMP relaxes the smooth muscle in the blood-vessel walls, allowing more blood to flow into the penis. Sildenafil blocks an enzyme called PDE-5, which normally Fildena CT 50 mg  down cGMP. This lets cGMP remain active longer, improving penile blood flow and helping produce an erection. The same blood-vessel relaxation can also occur elsewhere in the body, so some people experience headache, facial flushing, nasal congestion, dizziness, or a temporary drop in blood pressure. It doesn't normally increase blood flow everywhere indiscriminately, and it doesn't cause an erection without sexual stimulation. Important: sildenafil can cause a dangerous fall in blood pressure when combined with nitrates (such as nitroglycerin) or recreational “poppers.”