What Does a High Blood Pressure Reading Mean?

Medically Reviewed By William C. Lloyd III, MD, FACS
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man checking blood pressure at home

A high blood pressure reading can be disconcerting. After all, high blood pressure—or hypertension—is a serious condition that can lead to heart disease and stroke. But does one blood pressure reading that’s higher than it should be mean you have hypertension?

What is normal blood pressure?

Blood pressure is the force blood puts on the walls of arteries as it flows through them. When you measure blood pressure, the result consists of two numbers with the units of pressure, mm Hg (millimeters of mercury). The top number is systolic pressure—the highest pressure when the heart pumps blood through your arteries. The lower number is diastolic pressure—the lowest pressure when the heart rests between beats. A normal reading is 120/80 mm Hg or lower.

What is high blood pressure?

High blood pressure occurs when the force of blood on artery walls is too much for the walls to withstand. Even though the walls are strong and have several layers of cellular and connective tissues (including muscles), the additional pressure damages the wall with time, which further increases arterial pressure.

There are four different categories of high blood pressure:

  • Elevated blood pressure is a systolic reading of 120-129 mm Hg with a diastolic reading less than 80 mm Hg. This is prehypertension.

  • Stage I hypertension is a systolic reading of 130-139 mm Hg or a diastolic reading of 80-89 mm Hg

  • Stage II hypertension is a systolic reading of 140 mm Hg or higher or a diastolic reading of 90 mm Hg or higher

  • Hypertensive crisis is a systolic reading higher than 180 mm Hg or a diastolic reading higher than 120 mm Hg. Immediate medical care is necessary for readings this high.

The only way to know if your blood pressure is high is to measure it. High blood pressure rarely causes symptoms, so most people feel fine.

Why is blood pressure sometimes high?

There can be several causes of elevated blood pressure readings. Blood pressure varies throughout the day and with different levels of activity. As part of your body’s circadian rhythm, blood pressure is lowest during sleep, rises to a peak in the afternoon, and then falls through the evening.

Physical activity, stress, and anxiety and other emotions can also increase your blood pressure. Being nervous at medical appointments causes some people to have high readings. This is commonly called ‘white coat syndrome.’ Caffeine, nicotine, and some over-the-counter medicines can raise it as well.

So, one high reading does not necessarily mean you have elevated blood pressure or high blood pressure. Some of these factors could be responsible for a random elevated reading.

How does my doctor know if it is true high or elevated blood pressure?

Doctors use more than one high reading to diagnose elevated or high blood pressure. Usually, doctors will repeat two or more readings at least a minute apart to confirm a high reading. They may also check blood pressure in each arm since it can vary. If the readings remain high, you will likely need another appointment to recheck your blood pressure. Ideally, you should schedule the appointment at a different time of day to see if it makes a difference. Your doctor may request three or more appointments before diagnosing high blood pressure.

Your doctor may also ask you to monitor your blood pressure at home between appointments. Follow these steps to get the most accurate reading:

  • Avoid caffeine, nicotine, and physical exertion for 30 minutes beforehand.

  • Empty your bladder and sit quietly for five minutes.

  • Sit on a firm chair with your back straight, both feet on the floor, and your arm supported on a table or counter with your upper arm at heart level.

  • Place the cuff right above the bend of your elbow. Do not place the cuff over clothes.

  • Follow the instructions on your monitor to take the measurement.

When monitoring at home, check your blood pressure at the same time every day. Take 2 to 3 three readings at least one minute apart and record them.
If there is still any question about your blood pressure, your doctor can order an ambulatory blood pressure test. It uses a device that monitors your blood pressure for 24 hours.

What happens next?

If a high reading was truly a random occurrence, you may not need to do anything. But if your readings are consistently and repeatedly high, it’s time to take action. High blood pressure puts you at risk for serious complications, including heart attack and stroke. And elevated blood pressure will likely become full-blown high blood pressure if you ignore it. Recent research even suggests people with untreated white coat syndrome have an increased risk of heart disease and dying from heart disease. So, doctors are becoming more likely to address this condition.

If your readings fall in the elevated range, your doctor will likely discuss how to lower blood pressure with lifestyle changes. Steps include:

  • Eating a healthy diet that is low in salt and high in fiber, whole grains, and fresh fruits and vegetables

  • Getting regular physical exercise with 30 minutes of moderate-intensity activities five days a week

  • Limiting alcohol

  • Maintaining a healthy weight

  • Managing stress

  • Stopping nicotine use, including smoking and other forms

Making these changes is an important part of high blood pressure prevention. However, people with other medical conditions, such as diabetes, may need to add medication.

If your readings indicate stage I or II hypertension, your doctor will likely start medication. It depends on how high your numbers are, your other medical conditions, and your current lifestyle habits. Making lifestyle changes is still important even with medication. Healthy habits can help keep dosages low, which limits side effects.

The bottom line—if you have a high blood pressure reading, don’t freak out. But do talk with your doctor. Early diagnosis and treatment is the best way to prevent serious complications.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Sep 11
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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