Blood pressure is a measurement of the force against the walls of your arteries as your heart pumps blood through your body. Hypertension is another term used to describe high blood pressure.
Blood pressure readings are given as two numbers. The top number is called the systolic blood pressure. The bottom number is called the diastolic blood pressure. For example, 120 over 80 (written as 120/80 mmHg).
One or both of these numbers can be too high.
Normal blood pressure is when your blood pressure is lower than 120/80 mmHg most of the time.
High blood pressure (hypertension) is when your blood pressure is 140/90 mmHg or above most of the time.
If your blood pressure numbers are 120/80 or higher, but below 140/90, it is called pre-hypertension.
If you have heart or kidney problems, or you had a stroke, your doctor may want your blood pressure to be even lower than that of people who do not have these conditions.
Many factors can affect blood pressure, including:
The amount of water and salt you have in your body
The condition of your kidneys, nervous system, or blood vessels
Your hormone levels
You are more likely to be told your blood pressure is too high as you get older. This is because your blood vessels become stiffer as you age. When that happens, your blood pressure goes up. High blood pressure increases your chance of having a stroke, heart attack, heart failure, kidney disease, or early death.
You have a higher risk of high blood pressure if:
You are African American
You are obese
You are often stressed or anxious
You drink too much alcohol (more than 1 drink per day for women and more than 2 drinks per day for men)
If you have high blood pressure, you will have regular checkups with your health care provider.
Even if you have not been diagnosed with high blood pressure, it is important to have your blood pressure checked during your regular check-up, especially if someone in your family has or had high blood pressure.
Call your health care provider right away if home monitoring shows that your blood pressure is still high.
Most people can prevent high blood pressure from occurring by following lifestyle changes designed to bring blood pressure down.
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Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.