Blood pressure has two components: the higher systolic when your heart contracts, and the lower diastolic when your heart relaxes. You have high blood pressure when your systolic is above 120 or your diastolic is above 80. Ninety-one percent of Americans will eventually develop high blood pressure, which increases their risk for heart attacks, strokes, diabetes, kidney damage and other blood vessel disease.

Doctors do not diagnose high blood pressure with a single reading because some people have reactive hypertension that is not as dangerous as persistent hypertension. If you get one high reading in your doctor