High blood pressure, also known as hypertension, is a common disease that develops when blood flows through your arteries at higher-than-normal pressures. Your blood pressure is made up of two numbers: systolic and diastolic. Systolic pressure is the pressure when the ventricles pump blood out of the heart. Diastolic pressure is the pressure between heartbeats when the heart is filling with blood.

Your blood pressure changes throughout the day based on your activities. For most adults, a normal blood pressure is less than 120 over 80 millimeters of mercury, which is written as your systolic pressure reading over your diastolic pressure reading—120/80 mm Hg. Your blood pressure is considered high when you have consistent systolic readings of 130 mm Hg or higher or diastolic readings of 80 mm Hg or higher.

You usually don’t have symptoms from high blood pressure until it has caused serious health problems. About 1 in 3 U.S. adults with high blood pressure aren’t even aware they have it and are not being treated to control their blood pressure. In fact, that is why it is important to have your blood pressure checked at least once a year.

To control or lower high blood pressure, your doctor may recommend that you adopt a heart-healthy lifestyle. This includes choosing heart-healthy foods such as those in the DASH eating plan. You may also need to take medicines. Controlling or lowering blood pressure can help prevent or delay serious health problems such as chronic kidney disease, heart attack, heart failure, stroke, and possibly vascular dementia.