Viagrez 50^TM treats erectile dysfunction and works by relaxing muscles and increases blood flow to particular areas of the body. Its effects last up to four hours. The most common side effects of Viagrez 50^TM are headache, facial flushing, and upset stomach. Rarely, blurred vision, or sensitivity to light may briefly occur. As well as treating impotence, Sildenafil Citrate can also be effective in treating Pulmonary Arterial Hypertension (PAH). Similarly to how it acts to relax muscles of the penis, it relaxes arterial walls; therefore, reducing resistance and pressure in the arteries. Sildenafil Citrate is solely active in relaxing muscles and increasing blood flow to the heart, lungs and penis due to PDE-5, yet vasodilation is not increased in other parts of the body.