What Is Abnormal Blood Pressure?

Your blood pressure is the force of your blood as it moves through the arteries in your body. A blood pressure measurement is made up of two numbers: systolic blood pressure and diastolic blood pressure.

When your blood pressure is not within a normal range, it puts you at risk of serious health problems including heart attack and stroke. High blood pressure is generally a greater risk. It's also called hypertension. Low blood pressure is called hypotension.

This article discusses what blood pressure level is considered normal, what it means when your blood pressure is too low or too high, how blood pressure conditions are treated, and when to see a healthcare provider.

What Is Normal Blood Pressure?

Having a normal blood pressure means that your systolic blood pressure ranges (on average) from 90 to 120 millimeters of mercury (mmHg). Your diastolic blood pressure is 60 to 80 mmHg.

The American College of Cardiology (ACC) and the American Heart Association (AHA) recommend that adults should have their blood pressure checked at least once a year. If an adult has one or more risk factors for high blood pressure—for example, a family history or a history of smoking—they should be screened at least twice a year.

What Is High Blood Pressure?

The ACC and the AHA recognize multiple stages of hypertension.

Elevated

An elevated blood pressure means that your systolic blood pressure ranges (on average) from 120 to 129 mmHg and your diastolic blood pressure is less than 80 mmHg.

If left untreated, elevated blood pressure puts you at risk for developing stage 1 or stage 2 hypertension.

Stage 1

Stage 1 hypertension means that your systolic blood pressure is between 130 to 139 mmHg or your diastolic blood pressure is between 80 to 89 mmHg.

Stage 2

Stage 2 hypertension means that your systolic blood pressure is 140 mmHg or higher or your diastolic blood pressure is 90 mmHg or above.

Understanding the ACC/AHA Definition

It's important to mention that the definition of high blood pressure according to the ACC/AHA differs slightly from other professional societies, such as the European Society of Cardiology and the European Society of Hypertension (ESC/ESH).

The ESC/ESH defines high blood pressure as a systolic blood pressure that is 140 mmHg or higher or a diastolic blood pressure that is 90 mmHg or higher.

The differences in definition are based on results from large studies that examined the link between blood pressure and the occurrence of heart attacks and strokes.

Symptoms and Complications

Hypertension is often referred to as the "silent killer" because it often causes no symptoms (regardless of the stage) unless dangerous complications develop. High blood pressure puts you at risk for other serious conditions such as:

• Heart attack, which may cause chest pain or shortness of breath
• Heart failure, which may cause swelling, fatigue, and trouble breathing
• Stroke, which may cause headache, weakness, paralysis, or blurry vision
• Chronic kidney disease and kidney failure, which may cause elevated levels of creatinine in the blood, higher levels of white and red blood cells, and protein in the urine

Treating High Blood Pressure

Treatment for high blood pressure typically involves lifestyle changes along with one or more medications. If you have elevated high blood pressure, lifestyle changes are the first step to avoid the progression to stage 1 or stage 2 hypertension.

Lifestyle Changes

Lifestyle changes that can lower blood pressure include:

• Restricting salt in your diet by avoiding processed foods and eating fresh foods
• Losing weight if you're overweight or obese
• Engaging in regular physical activity—at least 30 minutes a day, most days of the week
• Limiting alcohol consumption
• Quitting smoking

Your healthcare provider may also recommend the DASH (Dietary Approaches to Stop Hypertension) diet, which has been found to lower blood pressure. This diet is rich in fruits, vegetables, and whole grains, and low in red meats and sweets.

Medications

Medication, along with lifestyle changes, is often very effective in lowering a person's blood pressure.

The drugs used to treat high blood pressure can be broken into four main categories:

• Thiazide diuretics
• Angiotensin-converting enzyme (ACE) inhibitors
• Calcium channel blockers
• Angiotensin receptor blockers (ARBs)

Finding the right medication, or the right combination of drugs, to control your high blood pressure often requires a trial-and-error process. Your healthcare provider will help you to keep your treatment plan on target.

What Is Low Blood Pressure?

Low blood pressure, called hypotension, is defined as a systolic blood pressure that is less than 90 mmHg. It has several potential causes, such as:

• Pregnancy
• Underlying heart conditions
• Certain medications
• Dehydration
• Shock from an infection (septic shock) or allergic reaction (anaphylactic shock)

Low blood pressure is generally not worrisome unless you have symptoms such as lightheadedness, dizziness, or fainting.

Depending on what is causing your low blood pressure, other potential symptoms may include:

• Nausea
• Blurry vision
• Cool, clammy skin
• Fatigue
• Rapid breathing
• Thirst

Treating Low Blood Pressure 

The treatments for low blood pressure involve addressing the underlying cause.

For instance, if you're experiencing low blood pressure from dehydration, the treatment would be to replace fluids and electrolytes, minerals that play a key role in keeping your body healthy.

Summary

Your blood pressure is measured with a blood pressure cuff and recorded in millimeters of mercury (mmHg). A normal systolic blood pressure is 90 to 120 mmHg (the top number) while a normal diastolic pressure is 60 to 80 mmHg (the lower number).

Your blood pressure is considered elevated when the systolic number is between 120 and 129. The stages of hypertension then increase from there, with a serious hypertensive crisis defined as anything at or above 180/120.

Lifestyle changes and medication are used to control high blood pressure. Low blood pressure can be a problem too, but treatment usually focuses on the underlying condition that's causing it.

A Word From Verywell

Even if your blood pressure is normal, it's important to engage in healthy lifestyle habits—the same ones you would engage in if your blood pressure were high. These habits include losing excess weight, exercising, reducing alcohol consumption, and not smoking.