What is normal and high blood pressure

A blood pressure reading below 120/80 mmHg is considered normal. In general, lower is better. However, very low blood pressure can sometimes be a cause for concern and should be checked out by a doctor.

Doctors classify blood pressures under 140/90 mmHg as either normal or prehypertension.

• Normal blood pressure is lower than 120/80 mmHg.
• Prehypertension is blood pressure between 120 and 139 for the top number, or between 80 and 89 for the bottom number. For example, blood pressure readings of 138/82, 128/89, or 130/86 are all in the prehypertension range. If your blood pressure is in the prehypertension range, it is more likely that you will end up with high blood pressure unless you take action to prevent it.

 High Blood Pressure

A blood pressure of 140/90 mmHg or higher is considered high blood pressure. Both numbers are important. If one or both numbers are usually high, you have high blood pressure.

If you are being treated for high blood pressure and have repeated readings in the normal range, you still have high blood pressure.

There are two levels of high blood pressure: stage 1 and stage 2 (see the chart below).

Categories for Blood Pressure Levels in Adults (in mmHg, millimeters of mercury)

For adults 18 and older who are not on medicine for high blood pressure; are not having a short-term serious illness; and do not have other conditions, such as diabetes and kidney disease.

Note: When systolic and diastolic blood pressures fall into different categories, the higher category should be used to classify blood pressure level. For example, 160/80 mmHg would be stage 2 high blood pressure.

There is an exception to the above definition of high blood pressure. A blood pressure of 130/80 mmHg or higher is considered high blood pressure in people with diabetes and chronic kidney disease.

Source http://www.nhlbi.nih.gov/