What is blood pressure?

As blood is pumped by the heart around the body, the pressure with which it pushes against the walls of blood vessels changes.

When the heart squeezes blood into the arteries, the pressure goes up.

When the heart is relaxed, the pressure is lower.

Your blood pressure is a measurement taken of the highest reading and the lowest reading.

It is given as 2 numbers — highest (systolic) over lowest (diastolic).

• Systolic is the pressure in the artery as the heart contracts. This is represented by the first number.
• Diastolic is the pressure in the artery when the heart is relaxing and being filled with blood. This is represented by the second number.

What is high blood pressure?

Blood pressure is measured in units of as millimetres of mercury (written as mmHg). Your blood pressure is considered high if the reading is more than 140/90mmHg. Blood pressure over this level puts you at higher risk of having a heart attack or stroke (cardiovascular disease).

This is true whether the first number (systolic) is higher than 140, or the second number (diastolic) is higher than 90, or both.

High blood pressure is also known as hypertension. More than 1 in every 3 Australians over the age of 18 has high blood pressure.

If your blood pressure is below this number, you are considered to have a reduced cardiovascular risk.

There are lower blood pressure targets, (usually below 130/80mmHg) for people with heart disease, diabetes, kidney disease and other health conditions.

Why do I need to know my blood pressure?

It’s important to have your blood pressure measured, because if it is too high, it affects the blood flow to your organs. This increases your chances of developing heart disease, stroke, chronic kidney disease, eye disease, erectile dysfunction and other conditions.

Current Australian guidelines recommend that if you have persistent raised blood pressure you should talk to your doctor or specialist about taking medicine to lower your blood pressure.

Very occasionally, people with very high blood pressure are at serious risk of problems. They may need urgent treatment in hospital to reduce the immediate risk of a stroke or heart attack.

If you’re over 18 years, you should have your blood pressure checked by your doctor at least every 2 years, or more often if advised.

What causes high blood pressure?

For most people, the cause of high blood pressure is not known. However, it is clear that various conditions and behaviours make high blood pressure more likely. These are known as risk factors and include:

• leading a sedentary lifestyle (a lifestyle with little or no exercise)
• smoking
• having obesity
• a diet with a high salt intake and/or high alcohol consumption
• high blood cholesterol level
• a family history of high blood pressure
• diabetes

In a few people, there is a known cause, such as narrowing of the arteries to the kidney or some hormonal conditions.

What are the symptoms of high blood pressure?

Most people with high blood pressure have no symptoms and feel quite well. This is why it’s important to see your doctor and have your blood pressure checked regularly, especially if you are over 18 years of age or have one or more of the risk factors listed above.

Rarely, people with very high blood pressure may experience headache, dizziness or the sudden effects of diseases of the arteries such as chest pain or stroke.

How is high blood pressure diagnosed?

Your blood pressure varies from day to day, even from moment to moment depending on your general health and activity levels.

Generally, if you have a blood pressure reading taken on 2 separate days that is greater than 140/90mmHg, you have high blood pressure. Your doctor may ask you to check your blood pressure at home or wear a monitor over a 24-hour period. This will help you and your doctor to see how your blood pressure varies over time and to make sure you get an accurate reading.

What is the treatment for high blood pressure?

Mild high blood pressure can often be treated by making lifestyle changes, including:

• doing regular physical activity
• stopping smoking
• improving your diet to reduce salt and fat and by eating lots of fruit and vegetables
• losing weight
• limiting your alcoholintake to no more than 2 drinks per day for males, or 1 drink per day for females with high blood pressure

However, lifestyle changes may not be enough. Some people also need medicines to help reduce blood pressure levels to within the normal range. While medicines are usually very effective at lowering blood pressure, they may cause side effects.

Usually, your doctors will start you on a low dose of a medicine. If it doesn’t work well enough, or if there are troublesome side effects, other medicines will be used until your blood pressure is controlled. This can take time, and some people will need more than one type of medicine to control their blood pressure.

Some people will take medicines for life. Others find that continuing to lose weight and changing their diet reduces the need for medicines.

If your blood pressure is very high or causing symptoms such as headache, or if you have conditions such as heart disease or diabetes, you may need urgent treatment with medicines to bring the blood pressure down to normal levels.

The Royal Australian College of General Practitioners recommends that you regularly review with your doctor or specialist any medicines you are taking for high blood pressure to assess the benefits and risks.

How can I prevent high blood pressure?

If you follow a healthy diet, maintain a healthy weight and avoid smoking, you will reduce your chances of having high blood pressure.

Resources and support

There are a number of resources and services available if you need help or more information on high blood pressure:

• The Heart Foundation provides information and support for people with high blood pressure, including a blood pressure action plan.
• The Stroke Foundation has more information about blood pressure and stroke.
• Dietitians Australia has a fact sheet about salt, ways to reduce salt intake, and when to see a dietitian.