Millions of adults may be unknowingly gambling with their health, according to a fresh warning from the NHS.
The health service is encouraging people to get familiar with their blood pressure readings during its Know Your Numbers campaign, highlighting a simple five-year check rule that could help spot those most at risk. In a social media post shared on Wednesday, September 9, it said: “Do you know what your blood pressure numbers mean? Find out this #KnowYourNumbers week! If you’ve checked your blood pressure, use our online tool to understand what your reading means and what you can do next.”
Anyone aged 40 or over who has not had a blood pressure test in the last five years is being urged to arrange one. The advice is especially important because high blood pressure frequently has no clear symptoms, so many people may be affected without knowing.
NHS England estimates that around 4.1 million people across England are living with undiagnosed high blood pressure. The condition is often referred to as a “silent killer” because it can quietly cause serious harm even when a person feels well.
When high blood pressure is not treated, it places additional strain on the heart and blood vessels. Over time, this can raise the risk of heart disease, heart attacks, strokes, heart failure and kidney disease.
The NHS is also promoting its online blood pressure checker, which lets people input a recent reading to understand what the numbers mean and what steps they may need to take next.
What the numbers mean
Blood pressure readings contain two numbers. The first figure, known as systolic pressure, shows the force as the heart pumps blood around the body. The second figure, called diastolic pressure, shows the pressure when the heart rests between beats.
For instance, a reading of 130/80 means the systolic pressure is 130 and the diastolic pressure is 80. As a general guide, the NHS says blood pressure is considered high at 140/90 or above when measured by a healthcare professional, or 135/85 or above when taken at home.
A reading below 120/80 is generally regarded as being in the healthy range, although blood pressure varies between people and throughout the day. A single high reading does not necessarily mean someone has hypertension.
If a clinic reading is 140/90 or above, NICE guidance recommends further monitoring, usually with a 24-hour ambulatory monitor or home blood pressure checks, to confirm whether the pressure remains high.
The NHS says people can get their blood pressure checked at their GP surgery, while many pharmacies offer free checks to people aged 40 and over in England. It is also possible to monitor blood pressure at home using a suitable machine.
When taking a reading at home, the NHS recommends sitting upright with your feet flat on the floor, resting your arm on a table and relaxing without talking during the test.
It advises taking a second reading a few minutes after the first to help make sure the result is accurate. The NHS says people should speak to their GP practice if they regularly use a home blood pressure monitor.
The latest push to get people checking their numbers comes after interest in NHS advice on high blood pressure surged. The NHS said its high blood pressure webpage received just over two million visits in 2025, up 36% on the previous year.
The message from health officials is simple: do not wait until you feel unwell. High blood pressure usually has no symptoms, which means checking the numbers may be the only way to discover there is a problem.
The NHS advises people who are worried about symptoms such as recurring headaches, blurred vision or chest pain to seek medical advice rather than relying on the online blood pressure checker.
And anyone with new symptoms such as dizziness, nausea, headache or chest pain should not use the online tool as a diagnostic test and should instead seek appropriate medical help. More information here.
