Roughly 37% of adults in England have high blood pressure. Almost 6 in 10 of them have never been diagnosed.
Among people already on treatment, half still have readings above the target.
The findings come from a cross-sectional study of more than 1.3 million adults, published September 23, 2026 in BMJ Public Health.
It is one of the largest single snapshots of blood pressure ever taken.
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Researchers at Oxford Population Health and Harvard T.H. Chan School of Public Health analyzed clinic readings from adults enrolled in the UK's Our Future Health program between 2022 and 2025.
Undetected across almost every group
Hypertension turned up in 37.2% of participants overall.
Prevalence climbed steeply with age, from 15% among adults 18 to 39 to 71% among those 80 and older.
Men were nearly 50% more likely to be affected than women, at 42% versus 29% after adjusting for age.
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The detection numbers are the most striking. The Oxford team found that 58.8% of people who met the criteria for hypertension had never been diagnosed.
Among those already on blood pressure medication, 50.2% still had readings at or above 140/90 mm Hg, the threshold the World Health Organization uses to define hypertension.
"While hypertension is largely a 'silent killer', the current approach to detecting and treating high blood pressure is not fit for purpose," said Wenyu Liu, medical statistician at Oxford Population Health and the paper's lead author.
Why so many people never find out
High blood pressure rarely announces itself. The American Heart Association says most people have no symptoms at all, and a reading is the only reliable way to know.
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Damage to the arteries, heart, kidneys, brain, and eyes builds quietly over years. By the time anything hurts, the harm is usually done.
The rare warning signs, when they do appear, tend to signal a hypertensive emergency rather than everyday hypertension.
Severe headache, chest pain, shortness of breath, vision changes, or stroke symptoms all need immediate care.
Who carries the highest hidden risk
The analysis linked undiagnosed hypertension most strongly to older age, being male, higher body mass index, Black ethnicity, a personal or family history of cardiovascular disease, and diabetes.
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Among participants who had never been told they had high blood pressure, 33.2% of men and 21.2% of women had clinic readings at or above 140/90.
Professor Bryan Williams of the British Heart Foundation put the stakes plainly. "High blood pressure remains the leading modifiable risk factor for cardiovascular disease, linked to around half of heart attacks and strokes in the UK," he said.
The picture in the US
The CDC estimates that nearly half of US adults have high blood pressure, about 119.9 million people. Around 1 in 6 does not know it.
Only about 22.5% have their blood pressure under control. In 2024, the condition was a primary or contributing cause of 680,179 deaths in the US.
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The single easiest step you can take today
For anyone who has not had a reading in the last year, the fix is quick. Most US pharmacies have a free automated blood pressure kiosk, and primary care visits, dental checkups, and workplace health fairs usually include one.
Home blood pressure cuffs cost less than $50 and are the tool the American Heart Association recommends for confirming a diagnosis and tracking treatment.
If a single reading comes in at or above 130/80, current US guidelines call for repeat measurements on separate days before any decision on treatment.
Anyone with symptoms of a hypertensive emergency should call 911.
This article is made and published by Mie Hermansen, who may have used AI in the preparation.