High blood pressure, or hypertension, is a condition in which the force of blood against artery walls is too strong. Over time, high blood pressure can damage the arteries, heart, and kidneys and can lead to heart disease and stroke.
High blood pressure can be treated effectively with lifestyle changes and medicines that can reduce the risk of complications.
Blood pressure readings consist of an upper number and a lower number (such as 120 over 90 or 120/90). The upper number is systolic blood pressure. The lower number is diastolic blood pressure. Blood pressure readings are measured in units called millimeters of mercury (mm Hg). Normal blood pressure is 119 mm Hg systolic over 79 mm Hg diastolic or below.
A person has high blood pressure (hypertension) when either or both of the following are present:
WebMD Medical Reference from Healthwise