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High Blood Pressure (Hypertension)

What high blood pressure is, how it is classified and diagnosed, its risk factors, and what county estimates of diagnosed high blood pressure can show.

Published 2026-10-22Sources verified 2026-10-22
Contents
  1. Beginner explanation
  2. Key definitions
  3. Condition characteristics
  4. Risk factors
  5. Prevention and public health context
  6. Texas data context
  7. Advanced material (optional)
  8. References

Beginner explanation

Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps. High blood pressure, also called hypertension, is when that force is consistently too high.[1]

Most people with high blood pressure have no signs or symptoms, so many do not know they have it. Measuring blood pressure is the only way to know.[1]

CDC reports that nearly half of U.S. adults (48.1%) have high blood pressure, and that only about 1 in 4 adults with high blood pressure has it under control.[3]

Key definitions

Systolic and diastolic
The two numbers of a blood pressure reading, in millimetres of mercury (mm Hg): systolic is the top number, diastolic the bottom.
Normal blood pressure
Systolic less than 120 and diastolic less than 80 mm Hg.
Stage 1 hypertension
Systolic 130–139 or diastolic 80–89 mm Hg.
Stage 2 hypertension
Systolic 140 or higher, or diastolic 90 or higher.
Severe hypertension
Systolic higher than 180 and/or diastolic higher than 120 mm Hg. With symptoms such as chest pain, shortness of breath, back pain, numbness, weakness, a change in vision or difficulty speaking, it is a hypertensive emergency: call 911.

Sources[1]

Condition characteristics

Blood pressure changes throughout the day with activity, so a health care team may take several readings over more than one visit, and may recommend monitoring at home with a validated monitor, before diagnosing high blood pressure. CDC notes that health professionals may use American College of Cardiology and American Heart Association guidelines, which set the categories above.[1]

Over time, high blood pressure can damage the heart, brain and kidneys. It increases the risk of heart disease (including heart attack, heart failure and chest pain), heart valve disease and stroke. It is linked to poorer cognitive function and a higher risk of dementia later in life, and it is a leading cause of chronic kidney disease.[1]

Risk factors

Conditions that raise risk include elevated blood pressure, diabetes, overweight and obesity, and pregnancy. CDC reports that about 3 in 4 people with diabetes also have high blood pressure.[1, 2]

Behaviors that raise risk include a diet high in sodium and low in potassium, too little physical activity, drinking too much alcohol, and using tobacco products, including smoking, vaping and nicotine pouches.[1, 2]

Some risk factors cannot be changed: age, family history and genetics, and race and ethnicity. Risk rises with age, and CDC reports that about 9 in 10 Americans will develop high blood pressure during their lifetime. Black people are more likely than other groups to develop high blood pressure, and tend to develop it at younger ages.[2]

Prevention and public health context

Many people can lower their blood pressure into a healthy range, or keep it there, through regular physical activity (about 30 minutes a day, 5 days a week), not smoking, a healthy diet that limits sodium and alcohol, keeping a healthy weight and managing stress. Some people also need medicine.[1]

Control differs between groups. Among adults recommended to take blood pressure medicine, CDC reports control in 46.8% of non-Hispanic Asian adults, 41.3% of Hispanic adults, 39.9% of non-Hispanic White adults and 31.8% of non-Hispanic Black adults.[3]

CDC advises anyone who thinks they have high blood pressure, or whose high blood pressure is not under control, to talk with their health care team.[1]

Texas data context

Vellora maps the PLACES high blood pressure measure: adults who report being told by a doctor, nurse or other health professional that they have high blood pressure, excluding high blood pressure only during pregnancy and borderline hypertension. It is a modeled estimate of diagnosed, self-reported high blood pressure, not a blood pressure reading.[4]

CDC notes that county maps of self-reported high blood pressure likely underreport the true burden, because about 1 in 6 adults with high blood pressure is unaware of it.[3]

CDC also cautions that PLACES estimates cannot be used to track change over time in a county.[5]

Related measures on the Explore map

Advanced material (optional)

CDC’s national figure of 48.1% counts adults with a systolic pressure above 130 mm Hg or a diastolic pressure above 80 mm Hg, or who take blood pressure medicine. PLACES counts adults who report a diagnosis. The definitions differ, so the two figures are not directly comparable.[3, 4]

Vellora note: A county’s PLACES estimate can therefore sit below the national 48.1% without meaning that fewer people there have high blood pressure.

References

  1. About High Blood Pressure. Centers for Disease Control and Prevention. https://www.cdc.gov/high-blood-pressure/about/index.html (accessed 2026-10-22).
  2. High Blood Pressure Risk Factors. Centers for Disease Control and Prevention. https://www.cdc.gov/high-blood-pressure/risk-factors/index.html (accessed 2026-10-22).
  3. High Blood Pressure Facts. Centers for Disease Control and Prevention. https://www.cdc.gov/high-blood-pressure/data-research/facts-stats/index.html (accessed 2026-10-22).
  4. PLACES Measure Definitions: Health Outcomes. Centers for Disease Control and Prevention. https://www.cdc.gov/places/measure-definitions/health-outcomes.html (accessed 2026-10-18).
  5. PLACES: Frequently Asked Questions. Centers for Disease Control and Prevention. https://www.cdc.gov/places/faqs/index.html (accessed 2026-10-18).
Vellora provides general education, not diagnosis or treatment advice. For personal health questions, consult a qualified health professional. In an emergency, call 911.