High blood pressure, also known as hypertension, is usually defined as having a sustained blood pressure of 140/90mmHg or above. The systolic pressure (higher number) is the force at which your heart pumps blood around your body, while the diastolic pressure (lower number) is the resistance to the blood flow in the blood vessels between heartbeats when blood is pumped around your heart. Both the systolic and diastolic pressures are measured in millimetres of mercury (mmHg) . The line between normal and raised blood pressure is not fixed, and blood pressure readings from 121/81mmHg to 139/89mmHg could mean youre at risk of developing high blood pressure if you do not take steps to keep your blood pressure under control.

It is important to note that everyones blood pressure will be slightly different, and whats considered low or high for you may be normal for someone else. If your blood pressure is moderately high (140/90mmHg or higher), or your GP feels that your risk of developing cardiovascular disease in the next 10 years is more than one in five, then you will be advised about changing your lifestyle and may also be prescribed medication. If your blood pressure is very high (180/110 mmHg or above), you should seek immediate medical attention.