What is high blood pressure? High blood pressure, also called hypertension, is a common condition in which the blood puts excessive force against the walls of the arteries, which induces changes in the vessels that can lead to serious complications, such as heart disease, stroke, and kidney failure. Hypertension is the most common reason for both doctors’ visits and prescriptions among non-pregnant adults. High blood pressure can be a result of a variety of conditions and diseases or a medical condition in itself. About one in three adults in the United States has high blood pressure, according to the National Heart, Lung and Blood Institute (Source: NHLBI). Blood pressure is the force exerted on the walls of the arteries as blood is pumped through your body. Your blood pressure is measured as two numbers followed by the units of pressure, such as 120/80 mm Hg (millimeters of mercury). The top number is called the systolic pressure, which is the highest pressure in your arteries as the heart is pumping blood. The bottom number is called the diastolic pressure and reflects the lowest pressure in your arteries when the heart is at rest between beats. Blood pressure measurements vary and show a moderate rise and fall in response to many situations. For example, blood pressure will rise during strenuous activity to ensure that all the cells of the body get sufficient amounts of oxygen-rich blood. Blood pressure may also rise in response to stressful situations. Blood pressure is normally lower during periods of relaxation or sleep. As a general guideline, adults should keep their blood pressure lower than 140/90 mm Hg. In addition, current guidelines consider consistent readings higher than 120/80 mm Hg as a condition called prehypertension, which should be monitored regularly and treated as needed to ensure that your blood pressure does not become higher over time. Extremely high blood pressure that occurs suddenly or the long-term effects of mild to moderately high blood pressure over time can lead to life-threatening complications, such as stroke, kidney failure, and heart attack. Seek regular medical care to check for and promptly treat high blood pressure to reduce the risk of complications. Seek immediate medical care (call 911) if you, or someone you are with, have symptoms such as chest pain, passing out, difficulty breathing, confusion, slurred speech, or problems with moving any part of the body.