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 is squeezing blood into the arteries, the pressure is high.
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 two figures — highest (systolic) over lowest (diastolic).
- Systolic — pressure in the artery as the heart contracts. This is represented by the top, higher number.
- Diastolic — pressure in the artery when the heart is relaxing and being filled with blood. This is represented by the bottom, lower number.
What is high blood pressure?
Your blood pressure is high if the reading is higher than 140/90 mm/Hg and is considered to then put you at higher risk of having a heart attack or stroke (cardiovascular disease). Having a blood pressure below this figure is even better in terms of reducing cardiovascular risk.
That is, you have high blood pressure if the higher figure (systolic) is higher than 140, or the lower figure (diastolic) is higher than 90, or both.
This is also known as hypertension. More than one-third of Australians over the age of 18 have high blood pressure.
There are lower blood pressure targets of less than 130/80 mmHg for people with cardiovascular disease, diabetes, kidney disease and other associated clinical conditions.
Why is your blood pressure important?
Your blood pressure is important because if it is too high, it affects the blood flow to your organs. Over the years, this increases your chances of developing heart disease, stroke, kidney failure, diabetes, eye disease, erectile dysfunction and other conditions.
Very occasionally, people with very high blood pressure are at serious risk of problems and need urgent treatment in hospital to reduce the risk of a stroke or heart attack.
Current Australian guidelines recommend that if you have persistent raised blood pressure over 160/100, but are at low risk of having a stroke or heart attack, you should talk to your doctor or specialist about taking medication to lower your blood pressure.
For further information, visit the Choosing Wisely Australia website.
If you’re over 18, you should have your blood pressure checked by your doctor at least every two years, or more often if advised.
What causes high blood pressure?
For most people, the cause of high blood pressure is not known. This is known as ‘essential’ or ‘primary’ hypertension.
But while the cause is not known, it is clear that various conditions and behaviour make high blood pressure more likely. These are known as risk factors, and include:
- leading a sedentary lifestyle (with little or no exercise)
- being overweight
- a diet with a high salt intake
- high blood cholesterol
- a family history of high blood pressure
- high alcohol consumption
- high salt intake
In a few people, there is an identifiable cause such as narrowing of the arteries of the kidney (renal stenosis) or some hormonal conditions.
What are the symptoms of high blood pressure?
Most people with high blood pressure have no symptoms, and may feel quite well. This is why it’s important to see your doctor and have your blood pressure checked regularly, especially if you have one or more of the risk factors listed above.
Check your symptoms with healthdirect’s Symptom Checker to get advice on when to seek medical attention.
Diagnosing high blood pressure
Your blood pressure varies from day to day, even moment to moment. Generally, if a person has a blood pressure reading greater than 140/90 taken on three different occasions, they have high blood pressure. Your doctor may ask you to monitor your blood pressure at home, or wear a monitor over a 24-hour period, to see how it varies and to make sure they get an accurate reading.
What is the treatment for high blood pressure?
Mild high blood pressure can often be treated by lifestyle changes, including:
- doing regular physical activity
- stopping smoking
- improving your diet to reduce salt, reduce fat and eat plenty of fruit and vegetables
- losing weight
- limiting your alcohol intake to no more than two drinks per day for men, or one drink per day for women with high blood pressure
Lifestyle changes may not be enough. Some people also need medication to help reduce blood pressure levels to normal. While medicines are usually very effective at lowering blood pressure, they may cause side effects in some people.
Usually doctors will start a person on a low dose of a medicine and see how it goes. If it doesn’t work well enough, or if there are troublesome side effects, other medicines will be used, sometimes in combination, until the blood pressure is controlled. This can take time. Some people will take medicines for life, although others will find that continuing to lose weight and change their diet reduces the need for medicines.
Someone whose blood pressure is very high or causing symptoms such as headache, or if they have conditions such as heart disease or diabetes, 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 medications you are taking for high blood pressure or high cholesterol to assess the ongoing benefits and risks. For further information, visit the Choosing Wisely Australia website.
Preventing high blood pressure
If you can follow a healthy diet, keep to a healthy weight and avoid smoking, you will reduce your chances of having high blood pressure.
There are a number of resources and services available if you need help or more information on high blood pressure:
Last reviewed: August 2018