Hypertension (high blood pressure) is a common condition that affects the body's arteries, where the force of the blood pushing against the artery walls is consistently too high and, as a result, the heart has to work harder to pump blood.

Blood pressure is measured in millimeters of mercury (mm Hg). In general, hypertension is a blood pressure reading of 130/80 millimeters of mercury (mm Hg) or higher.

The American College of Cardiology and the American Heart Association divide blood pressure into four general categories.

• Normal blood pressure. Blood pressure is 120/80 mm Hg or lower.
• Elevated blood pressure. The top number ranges from 120 to 129 mm Hg and the bottom number is below, not above, 80 mm Hg.
• Stage 1 hypertension. The top number ranges from 130 to 139 mm Hg or the bottom number is between 80 and 89 mm Hg.
• Stage 2 hypertension. The top number is 140 mm Hg or higher or the bottom number is 90 mm Hg or higher.

Blood pressure higher than 180/120 mm Hg is considered a hypertensive emergency or crisis. Seek emergency medical help for anyone with these blood pressure numbers. Untreated, high blood pressure increases the risk of heart attack, stroke and other serious health problems. It is important to have blood pressure checked at least every two years starting at age 18.

Healthy lifestyle habits, such as not smoking, exercising, and eating well, can help prevent and treat high blood pressure, while in other cases, drug therapy is needed.