High blood pressure is among the most common health conditions in the United States and one of the easiest to miss, because it usually causes no symptoms. This guide explains what the two numbers mean, where the thresholds sit, how home readings differ from clinic readings and what the evidence-based advice says about bringing them down.
How common is high blood pressure in the United States?
According to the Centers for Disease Control and Prevention (CDC), 48.1% of U.S. adults, about 119.9 million people, have high blood pressure. That estimate uses a broad definition: a measured systolic pressure above 130 mm Hg, a diastolic pressure above 80 mm Hg, or taking blood pressure medication. The figures come from national survey data covering 2017 to March 2020, and the CDC page was last updated in June 2026.
Control is the weaker part of the picture. The CDC reports that 22.5% of adults with high blood pressure, or 27.0 million people, have it under control, roughly 1 in 4. About 1 in 6 adults with the condition does not know they have it.
The stakes are real. The CDC says high blood pressure was a primary or contributing cause in 680,179 deaths in 2024, and it estimated annual costs associated with the condition at $219 billion in 2019.
What do the two numbers in a reading mean?
A reading such as 128/76 has two parts, measured in millimeters of mercury (mm Hg):
- Systolic pressure (the top number) is the pressure in the arteries when the heart beats.
- Diastolic pressure (the bottom number) is the pressure between beats, when the heart rests.
The NHS notes that the first number is always the higher one. Either number can be the one that is raised, which is why categories are defined by whichever is higher.
Which categories does the CDC use?
The CDC groups readings as follows:
| Category | Systolic (top) | Diastolic (bottom) |
|---|---|---|
| Normal | Under 120 | and under 80 |
| Elevated | 120 to 129 | and under 80 |
| Stage 1 hypertension | 130 to 139 | or 80 to 89 |
| Stage 2 hypertension | 140 or higher | or 90 or higher |
| Severe hypertension | Above 180 | and/or above 120 |
Readings above 180 systolic or 120 diastolic with no symptoms call for contacting a health care professional. The same readings with symptoms such as chest pain, shortness of breath, back pain, numbness, weakness, changes in vision or difficulty speaking are a hypertensive emergency, and the CDC says to call 911.
A single high reading does not make a diagnosis. Blood pressure changes through the day, so the CDC says providers may take multiple readings over more than one visit and may recommend monitoring at home with a validated monitor.
Why do home and clinic thresholds differ?
The NHS in the United Kingdom uses two thresholds: 140/90 or higher when measured by a health care professional, and 135/85 or higher when measured at home. The home figure is lower because readings taken in a relaxed setting tend to run lower than those taken in a clinic, where nerves can push numbers up.
If a clinic test suggests high blood pressure, the NHS says a person may be asked to use a monitor at home to check regularly over the next few days, or to wear a portable 24-hour monitor. Either approach gives a fuller picture than one appointment.
The NHS diagnosis page does not set out step-by-step home technique, so anyone buying a monitor should ask a clinician or pharmacist how to use it properly.
A worked example of averaging
Individual readings bounce around, which is why trends matter more than any single number. Illustrative arithmetic with three home readings:
| Reading | Systolic | Diastolic |
|---|---|---|
| First | 138 | 86 |
| Second | 132 | 84 |
| Third | 136 | 82 |
| Total | 406 | 252 |
| Average (total divided by 3) | 135.3 | 84 |
An average of about 135/84 sits right at the NHS home threshold of 135/85 on the systolic side. That is exactly the kind of result worth bringing to a clinician rather than interpreting alone. It also shows why one 138 should not cause alarm, and one 132 should not bring false reassurance.
Why is high blood pressure called a silent condition?
The CDC states that high blood pressure usually has no signs or symptoms, and that measuring it is the only way to know. The NHS adds that symptoms such as headaches, blurred vision or chest pain are rare. Anyone who has frequent headaches, blurred vision or intermittent chest pain should seek medical advice, and sudden, persistent chest pain needs emergency care.
That silence is the reason awareness gaps persist. A person can feel well for years while pressure quietly strains the heart, brain and kidneys.
What does sustained high pressure do to the body?
The CDC lists complications across three systems:
- Heart and blood vessels: heart disease, including heart attack, heart failure, angina and heart valve disease.
- Brain: stroke, and poorer cognitive function and higher dementia risk, especially when high blood pressure develops in midlife.
- Kidneys: damage, with high blood pressure a leading cause of chronic kidney disease.
The NHS lists a similar set of risks if the condition goes untreated, including vascular dementia.
Who is more likely to have it?
Risk rises with age, family history and certain medical conditions. The CDC lists elevated blood pressure, diabetes, overweight or obesity and pregnancy among conditions that raise risk, along with long-term stress and some medications. Behavioral factors include a diet high in sodium and low in potassium, too little physical activity, heavy alcohol use and tobacco use.
Prevalence also differs between groups. In CDC-cited research covering 2013 to 2023 survey data, 50% of men had high blood pressure versus 42.1% of women. By race and ethnicity, the estimates were 59.6% for non-Hispanic Black adults, 44.9% for Hispanic adults, 44.8% for non-Hispanic White adults and 42.7% for non-Hispanic Asian adults. Control among those recommended medication was lowest for non-Hispanic Black adults, at 31.8%, compared with 46.8% for non-Hispanic Asian adults.
The NHS also lists Black African, Black Caribbean and South Asian backgrounds among its risk factors.
Related conditions often travel together. The CDC’s figures on prediabetes and blood sugar overlap with the same cardiovascular risk picture, and checking one number is a good prompt to ask about the other.
What actually helps lower blood pressure?
Both agencies put lifestyle first. The CDC’s prevention advice includes:
- About 30 minutes of physical activity a day, 5 days a week.
- Not smoking.
- A healthy diet that limits sodium and alcohol.
- Keeping a healthy weight.
- Managing stress.
The NHS gives similar guidance, with a target of at least 150 minutes of exercise a week, advice to avoid regularly drinking more than 14 units of alcohol a week, and a suggestion to cut back on high-caffeine drinks. It also says even a small reduction in blood pressure lowers risk. Sleep is a related lever, and our guide on how to get better sleep covers habits that support recovery and stress control.
When are medicines used?
The CDC says healthy habits are the foundation, but many people also need medicine, taken as prescribed. The NHS says a GP usually prescribes medicine if blood pressure is very high, if the person has a higher risk of heart attack or stroke, or if it stays high despite lifestyle changes. Most are once-daily tablets, and some people need more than one.
The CDC estimates that about 34 million adults who may need blood pressure medication under current guidelines are not taking it. Closing that gap is one reason remote check-ins matter, and telehealth has made follow-up visits for readings and prescriptions easier for many patients.
Making the numbers part of routine care
Blood pressure is cheap to measure, quick to interpret and strongly tied to outcomes that people care about, from stroke to kidney function. With nearly half of adults meeting the CDC definition and only about a quarter of them controlled, the main opportunity is simple: know your numbers, understand which category they fall in and talk to a clinician about what the pattern means for you.
This article is general information, not medical advice. Talk to a qualified health professional about your own readings and treatment.
Sources: Centers for Disease Control and Prevention; NHS
