Frequently asked questions about high blood pressure

Here are the answers to your questions about hypertension - commonly called high blood pressure.

1. What causes high blood pressure?

While the cause of high blood pressure in most people remains unclear, a variety of conditions - such as getting little or no exercise, poor diet, obesity, older age and genetics - can lead to hypertension.

2. What are systolic and diastolic blood pressures?

The blood pressure reading is measured in millimetres of mercury (mmHg) and is written as systolic pressure - the force of the blood against the artery walls as your heart beats - over diastolic pressure - the blood pressure between heartbeats. For example, a blood pressure reading is written as 120/80mmHg, or “120 over 80”. The systolic pressure is 120 and the diastolic pressure is 80.

3. What is a normal blood pressure?

Blood pressure measurements can be classified as:

•  Normal or ideal blood pressure is a systolic pressure of 120mmHg or less and a diastolic pressure of 80mmHg or less
•  Systolic pressure between 120-139mmHg or diastolic pressure between 80-89mmHg is normal but higher than it should be
•  Systolic blood pressure of 140mmHg or more and/or diastolic blood pressure of 90mmHg or more is hypertension (high blood pressure)

4. What health problems are associated with high blood pressure?

Several potentially serious health conditions are linked to high blood pressure, including:

•  Atherosclerosis: a disease of the arteries caused by a build-up of plaque, or fatty material, on the inside walls of the blood vessels. Hypertension contributes to this build-up by putting added stress and force on the artery walls.
•   Heart disease: heart failure (the heart can’t adequately pump blood), ischaemic heart disease (the heart tissue doesn’t get enough blood), and hypertensive hypertrophic cardiomyopathy (enlarged heart) are all associated with high blood pressure. 
•  Kidney disease: hypertension can damage the blood vessels and filters in the kidneys, so that the kidneys cannot excrete waste properly. 
•   Stroke: hypertension can lead to stroke, either by contributing to the process of atherosclerosis (which can lead to blockages and/or clots), or by weakening the blood vessel wall and causing it to rupture.
• Eye disease: hypertension can damage the very small blood vessels in the retina.

5. How do I know if I have high blood pressure?

High blood pressure usually doesn’t have any symptoms, so you usually don’t feel it. For that reason, hypertension is usually diagnosed by a health care professional on a routine visit. This is especially important if you have a close relative who has hypertension or you yourself have risk factors for it.

If your blood pressure is extremely high, you may have unusually strong headaches, chest pain and heart failure (especially difficulty breathing and poor exercise tolerance). If you have any of these symptoms, seek medical advice immediately.