Hypertension, or high blood pressure, often does not have noticeable symptoms but, if left untreated, it can increase a person’s risk of heart attack and stroke. If blood pressure is too high, it puts extra strain on blood vessels, the heart and other organs, such as the brain, kidneys and eyes. Persistent hypertension can increase the risk of serious conditions such as heart disease; heart attacks; strokes; heart failure; peripheral arterial disease; aortic aneurysms; kidney disease; and vascular dementia.

Two numbers are used to measure blood pressure. Systolic pressure is the higher of the two and the one that measures the force at which the heart pumps blood around the body. The diastolic pressure - the lower number - is the resistance to the blood flow in the blood vessels. They're both measured in millimetres of mercury (mmHg).

Generally, high blood pressure is considered to be 140/90mmHg or higher, while ideal blood pressure is between 90/60mmHg and 120/80mmHg. Low blood pressure is considered to be 90/60mmHg or lower. A blood pressure reading between 120/80mmHg and 140/90mmHg could mean that a person is at risk of developing hypertension if measures are not taken to get it under control.