High Blood Pressure Stages and Classes

A blood pressure gauge and cuff.
A blood pressure gauge and cuff. PhotoAlto/Eric Audras/Getty Images

There are two different “typing” schemes to describe high blood pressure: classification and staging. Classification refers to what is causing your high blood pressure and there are two types: primary and secondary. Staging refers to the severity of your high blood pressure reading and there are two stages: Stage I and Stage II.

The Classification System

First, your health care provider will classify your high blood pressure as either primary or secondary.

Primary hypertension, also known as essential or idiopathic hypertension, is the most common diagnosis and typically develops as you get older. This classification indicates your health care provider has found no clear cause of your high blood pressure. Primary hypertension may be linked to genetics, a bad diet, not getting enough exercise and obesity. Around 90 percent of all people with high blood pressure have primary hypertension, according to the National Institutes of Health.

Secondary hypertension is more definitive but far less common. The underlying cause of this class of hypertension is usually a medical condition affecting your arteries, heart, kidneys or endocrine system. Your high blood pressure may normalize as your health condition improves.

Pregnant women with high blood pressure usually have secondary hypertension.

The Staging System

The system used to stage high blood pressure is based simply on the numbers, both systolic and diastolic, found in your blood pressure reading:

  • The systolic number, a measurement of your blood pressure while your heart pumps blood, appears on the top.
  • The diastolic number, a measurement of your blood pressure while your heart rests between beats, appears on the bottom.

Blood pressure has essentially two stages: Stage I and Stage II. Your blood pressure reading might also be explained as prehypertension or a hypertensive crisis.

The Hypertension Stages

Prehypertension means your blood pressure reading is higher than normal, but not high enough to diagnose you as Stage I or Stage II. You should take prehypertension seriously because it can lead to high blood pressure.

Stage I Hypertension refers to blood pressure with a systolic reading of 140-159 mm Hg and a diastolic reading of 90-99 mm Hg.

Stage I is early, but still serious, form of high blood pressure. After you receive your diagnosis, doctors may choose to either begin treatment with medicine or to allow for a “grace period,” during which you are instructed to make certain changes in your diet and exercise regimen in an attempt to reduce the blood pressure.

Stage II Hypertension indicates you have moderate to severe high blood pressure with a systolic reading of 160 mm Hg or higher and a diastolic reading of 110 mm Hg or higher.

Treatment guidelines allow for much less flexibility in the initial approach to Stage II Hypertension, and those diagnosed at this stage are almost universally started on anti-hypertension medicines immediately. Stage II Hypertension also requires more frequent blood pressure checks and more careful monitoring.

Hypertensive crisis is a very serious condition that requires emergency care.

Patients with this diagnosis have a systolic reading higher than 180 mm Hg and a diastolic reading higher than 110 mm Hg.


American Heart Association: Understanding Blood Pressure Readings (2015)

Mayo Clinic: Definition of Secondary Hypertension (2013)

National Institutes of Health: Description of High Blood Pressure (2015)