What is blood pressure?
Blood pressure is the force of blood pushing against the walls of your arteries as the heart pumps. It is given as two numbers, such as 120/80, measured in millimeters of mercury (mmHg).
The top number, called systolic pressure, measures the pressure when the heart beats and pushes blood out. The bottom number, diastolic pressure, measures the pressure when the heart rests between beats. Both numbers matter for health. Blood pressure naturally rises and falls through the day with activity, stress and sleep.
High blood pressure, or hypertension, makes the heart work harder and can damage blood vessels over time. It raises the risk of heart attacks, strokes, kidney disease and vision problems. It often has no symptoms, which is why it is sometimes called a silent killer and should be checked regularly.
Low blood pressure
Low blood pressure, or hypotension, can cause dizziness or fainting, especially when standing up quickly. It is not always a problem and is common in healthy, active people. Very low blood pressure, however, can be a sign of a serious condition and needs medical attention.
Did You Know?
Blood pressure is measured in millimeters of mercury because early devices measured how high the pressure could push a column of liquid mercury.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.