Hypertension, also known as high blood pressure, is a very common condition.¹ High blood pressure happens when blood moving through the body pushes too much on the walls of the arteries, which are a type of blood vessel.¹ Nearly half of American adults have high blood pressure.1 Learn more about high blood pressure, its symptoms, and its long-term effects.

What Is Hypertension?

Hypertension is high blood pressure.² High blood pressure is sometimes abbreviated as HBP.

There are two main types of high blood pressure.³ Primary hypertension is high blood pressure that has no identifiable cause. Most cases of high blood pressure are primary hypertension.

Secondary hypertension is a form of high blood pressure that is caused by a medical condition that was present before the high blood pressure diagnosis.³ In most cases, if the initial condition resolves, the blood pressure will also return to normal. Secondary hypertension is responsible for only a small portion of hypertension cases.

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What Are High Blood Pressure Symptoms?

High blood pressure usually doesn’t cause any obvious symptoms, especially in the beginning stages.^1,2 A lot of people don’t even know they might have it. About 1 in 3 U.S. adults with high blood pressure don’t even know that they have it and aren’t being treated.² That’s why high blood pressure is frequently called a “silent killer”.^1,4

Blood spots in the eyes, facial flushing, and dizziness may be indirectly associated with high blood pressure, but these are not causes or signs of high blood pressure.⁴

Some people think that high blood pressure can cause headaches and nosebleeds, but that’s not usually true in most cases.⁴ If you have a headache or nosebleed and your blood pressure is unusually high, this might be a hypertensive crisis. A hypertensive crisis is a medical emergency that requires medical attention.

What Causes High Blood Pressure?

Most cases of high blood pressure are primary hypertension and have no identifiable cause.³ High blood pressure develops gradually over time.⁵ There are a number of factors that can increase a person’s risk of developing high blood pressure.³ These risk factors can be divided into two groups: factors that can’t be changed (nonmodifiable) and factors that can be changed (modifiable).

Nonmodifiable risk factors include family history, age, and gender.³ Having a close blood relative (e.g., parent, sibling) with high blood pressure can increase the risk of developing high blood pressure. Generally, increasing age increases the risk. Gender also affects risk. Before the age of 64, men have an increased risk of developing high blood pressure. After 65 years or more, women have an increased risk of developing high blood pressure.

Race is another nonmodifiable risk factor that can affect a person’s risk of developing high blood pressure.³ In the U.S., Black people tend to develop high blood pressure more often than people of any other racial background. About 55% of Black adults have high blood pressure.⁶ These patients also tend to have higher rates of more severe high blood pressure and tend to be diagnosed earlier in their lives than people of other racial backgrounds. Historical and systemic factors, like not having access to care and healthy foods and other societal issues, are major contributors to the imbalance of high blood pressure diagnoses among Black adults in the community.

Modifiable risk factors that can increase the risk of developing high blood pressure include:³

Lack of physical activity
Unhealthy diet (such as a diet high in salt, calories, fat, and sugar)
Excess body weight
Regular, excessive alcohol consumption
Obstructive sleep apnea
High cholesterol
Diabetes
Smoking and tobacco use and exposure
Excess stress

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How Is Blood Pressure Measured?

A healthcare provider usually measures the blood pressure using an inflatable cuff placed on the arm and a stethoscope, gauge, or electronic sensor.^{2, 7} Checking blood pressure is easy and painless.²

There are a few things that patients can do to help get the most accurate blood pressure measurement.^{2, 7}

Wear clothing that can be removed or easily moved so clothing is not covering the location of the cuff.
Avoid caffeine, exercise, and smoking within 30 minutes of having blood pressure measured.
Go to the bathroom before the measurement.
Sit in a chair with the feet on the floor, the back supported, and the arm resting on a table at the level of the heart. Relax here for more than 5 minutes before the measurement.
Do not speak during the blood pressure measurement.

When a healthcare provider checks the blood pressure of a patient for the first time, they might check it in both arms.^{2, 7} If the measurement is higher in one arm than the other, they should continue to measure the blood pressure in the arm that gives the higher measurement.⁷

What Do the Numbers in a Blood Pressure Measurement Mean?

There are two numbers in a blood pressure measurement.⁸ The first number is the force of blood on the artery walls when the heart beats and blood is pumped out of the heart. This number is called the systolic (si-stol-ik) blood pressure, or SBP. The second number is the force of blood on the artery walls when the heart is filling up with blood in between beats. This number is called the diastolic (dy-uh-stol-ik) pressure, or DBP.

Blood pressure is measured in the units of millimeters of mercury.^{2, 8} This is because the first pressure gauges used to accurately measure blood pressure used mercury. Millimeters of mercury is often abbreviated as mm Hg.

Blood pressure measurements include both the systolic and diastolic blood pressure numbers with a “/” in between, like a fraction.^{2, 8} When people talk about blood pressure, the 2 numbers are separated by the word “over”, to represent the fraction. For example, 120/80 is usually called “120 over 80.”

How Is High Blood Pressure Diagnosed?

High blood pressure is usually diagnosed using multiple measurements of the blood pressure taken at a doctor’s office or clinic.² An average of at least two blood pressure measurements on at least two separate occasions are used to make the diagnosis.⁷

Normal blood pressure is when systolic blood pressure measurements are usually less than 120 mm Hg and diastolic blood pressure measurements are usually less than 80 mm Hg.^{7, 8}

Elevated blood pressure is when systolic blood pressure measurements are usually in the range of 120-129 mm Hg and diastolic blood pressure measurements are usually less than 80 mm Hg.^{7, 8} Patients with elevated blood pressure often progress to having high blood pressure unless they make lifestyle changes.⁸

High blood pressure can be divided into two stages:^{7, 8}

Stage 1 is when systolic blood pressure measurements are usually in the range of 130-139 mm Hg or when diastolic blood pressure measurements are usually in the range of 80-89 mm Hg.
Stage 2 is when systolic blood pressure measurements are usually at least 140 mm Hg or when diastolic blood pressure measurements are usually at least 90 mm Hg.

Blood pressures of more than 180/120 mm Hg might be a hypertensive crisis.⁸ A hypertensive crisis is a medical emergency that requires medical attention.

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What Are the Long-Term Effects of Hypertension?

Hypertension can result in long-term effects to the body. Blood vessels become damaged when the blood pressure remains high over time.⁹ Cholesterol can build up in the injured blood vessels. This causes the arteries to become stiffer and narrower.

High blood pressure that is not diagnosed or is uncontrolled can lead to serious health problems. Some of these health problems include:^{2, 9}

Aneurysm
Chest pain
Heart attack
Heart failure
Chronic kidney disease or kidney failure
Eye damage/vision loss
Peripheral artery disease or carotid artery disease
Sexual dysfunction
Stroke

High Blood Pressure Prevention

The best way to reduce the risk of developing high blood pressure is by living a healthy lifestyle.^{2, 7, 10} This can involve:

Eating healthy foods that are low in salt and high in potassium
Limiting alcohol
Keeping physically active
Maintaining a healthy body weight
Quitting smoking
Managing stress
Getting enough sleep

Resources for Learning More About High Blood Pressure

Some trusted resources for learning more about high blood pressure include:

The Facts About High Blood Pressure – American Heart Association (AHA)
Learn About High Blood Pressure – Centers for Disease Control and Prevention (CDC)
What Is High Blood Pressure – National Heart, Lung, and Blood Institute (NHLBI)