Sildenafil is used to treat high blood pressure in the blood vessels in the lungs (pulmonary arterial hypertension). Sildenafil works by relaxing and widening the blood vessels in the lungs, and ultimately lowering the pressure in the lungs.
This should improve your symptoms such as breathlessness, and increase your ability to exercise. This medication has to be taken on a daily basis.
This medication may also be used for other conditions. Check with your healthcare professional if you are unsure why you are given this medication.