Diovan^® (valsartan) is a prescription medication used to treat several conditions related to the heart and blood vessels, such as high blood pressure and congestive heart failure, and also to help improve survival rates for heart attack patients. Part of a class of drugs called angiotensin II receptor blockers, Diovan works by causing the blood vessels of the heart to relax. This, in turn, makes the heart more efficient by letting more blood flow from the heart to the rest of the body. Diovan comes as a tablet taken once or twice daily, with or without food. Most people tolerate Diovan well, but there are some side effects, including fatigue, dizziness, and infection with a virus (such as the common cold or flu). Some of the conditions to let your healthcare provider know about before you take Diovan include heart disease, liver disease, and diabetes.