High blood pressure, also called hypertension, is one of the most common health conditions in the UK. Around one in four adults has it, and many of them do not even know. Understanding what it is, what causes it, and what it means for your health is the first step towards taking care of yourself.
What Is Blood Pressure?
Blood pressure is the force that your blood puts on the walls of your blood vessels as it moves around your body. Every time your heart beats, it pushes blood out into your arteries. The pressure that creates is measured with two numbers.
Systolic and Diastolic: What Do the Numbers Mean?
A blood pressure reading is always shown as two numbers, for example 120/80. Here is what each number means:
| Number | Name | What It Measures |
| Top number (e.g. 120) | Systolic pressure | The pressure when your heart beats and pushes blood out |
| Bottom number (e.g. 80) | Diastolic pressure | The pressure when your heart rests between beats |
Blood pressure is measured in millimetres of mercury, written as mmHg. A reading below 120/80 mmHg is generally considered healthy. According to the NHS, a reading of 140/90 mmHg or higher is usually classed as high blood pressure.
What Is High Blood Pressure (Hypertension)?
High blood pressure means the force on your blood vessel walls is higher than it should be. Over time, this extra pressure can damage your arteries, heart, kidneys, and other organs.
High blood pressure is often called a “silent condition” because it rarely causes noticeable symptoms. Most people feel completely fine, which is why so many people go undiagnosed for years.
What Causes High Blood Pressure?
For most people, there is no single cause. Instead, a mix of factors tends to push blood pressure up over time. These include:
- Diet – eating too much salt is one of the biggest risk factors
- Being overweight – extra body weight puts more pressure on your heart
- Not being active enough – regular exercise helps keep blood pressure in a healthy range
- Stress – long-term stress can raise blood pressure over time
- Alcohol – drinking more than the recommended amount regularly
- Smoking – damages blood vessel walls and raises blood pressure
- Age – blood pressure tends to rise naturally as we get older
- Family history – if a close relative has high blood pressure, your risk is higher
- Ethnicity – people of Black African or Caribbean background are at higher risk
In around one in ten cases, high blood pressure is caused by another health condition, such as kidney disease or a thyroid problem. This is sometimes called secondary hypertension.
Why Is High Blood Pressure Dangerous?
Even though you may not feel unwell, high blood pressure puts a constant strain on your heart and blood vessels. Over many years, this can lead to serious health problems including:
- Heart attack – when blood flow to part of the heart is blocked
- Stroke – when blood flow to part of the brain is cut off or interrupted
- Heart failure – when the heart becomes too weak to pump properly
- Kidney disease – high pressure can damage the tiny blood vessels in the kidneys
- Vision loss – damage to the blood vessels in the eyes
Because there are often no warning signs, hypertension is sometimes described as a “silent killer.” Many people only find out they have it when they get a routine check-up or are tested for something else.
How Is High Blood Pressure Diagnosed?
The only way to know if you have high blood pressure is to have it measured. A GP, pharmacist, or nurse can do this quickly and painlessly. Many pharmacies in the UK offer free blood pressure checks.
A single high reading does not always mean you have hypertension. Your doctor may ask you to monitor it at home over a few days, or wear a portable monitor that takes readings over 24 hours, before making a diagnosis.
Can High Blood Pressure Be Treated?
Yes. Many people with high blood pressure are able to bring it down through lifestyle changes, including:
- Reducing salt in their diet
- Eating more fruit and vegetables
- Exercising regularly (aim for 150 minutes of moderate activity per week)
- Drinking less alcohol
- Stopping smoking
- Managing stress through relaxation, sleep, or talking to someone
When lifestyle changes are not enough on their own, doctors may prescribe medication. There are several types of blood pressure medicine available, and finding the right one for you may take a little time.
What Is Being Done to Improve Hypertension Treatment?
Researchers are always working to develop better treatments for high blood pressure. Clinical trials are one of the most important ways this happens. A hypertension clinical trial gives eligible participants access to new treatments being tested under close medical supervision.
Taking part in a trial is a well-considered decision. Before anything starts, you will be invited to attend a screening appointment to see if you are suitable. You can find out more about what to expect at a screening visit on the 4MCS website.
If you are curious about whether taking part in research is right for you, it is worth reading about why people join clinical trials and what they tend to gain from the experience.
Key Points to Remember
- High blood pressure (hypertension) is when blood pushes too hard against your artery walls
- Systolic is the top number; diastolic is the bottom number
- A reading of 140/90 mmHg or above is usually classed as high
- It often has no symptoms, which is why it is known as a silent condition
- Common causes include diet, lack of exercise, stress, and genetics
- It can be managed with lifestyle changes and, where needed, medication
- Getting tested is the only way to know if you have it
