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While the cause of high blood pressure in most people remains unclear, inactivity, poor diet, obesity, older age, and genetics -- can all contribute to the development of hypertension

The blood pressure reading is measured in millimeters of mercury (mmHg) and is written as systolic pressure, the force of the blood against the artery walls as your heart beats, over diastolic pressure, the blood pressure between heartbeats. For example, a blood pressure reading is written as 120/80 mmHg, or "120 over 80". The systolic pressure is 120 and the diastolic pressure is 80.

The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure has classified blood pressure measurements into several categories:

  • Normal blood pressure is systolic pressure less than 120 and diastolic pressure less than 80 mmHg.
  • Elevated is systolic pressure of 120-129 and diastolic pressure less than 80 mmHg.
  • Stage 1 Hypertension is systolic pressure of 130-139 or diastolic pressure of 80-89 mmHg.
  • Stage 2 Hypertension is systolic pressure of 140 or greater ordiastolic pressure of 90 or greater.
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