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Overview of high blood pressure

Your heart pumps blood around your body through blood vessels called arteries. With each heartbeat, the blood pushes against the artery walls. The strength of this pushing is your blood pressure.

A blood pressure reading has two numbers and is written like 120/80 mmHg (millimetres of mercury).

The first (top) number is the pressure when your heart pumps (systolic pressure). The second (bottom) number is the pressure when your heart relaxes (diastolic pressure).

For most people, the first number should be between 110 and 130 mmHg and the second between 70 and 80 mmHg.

Generally, the lower your blood pressure, the better. But the level of blood pressure that is high for you depends on your other health conditions such a diabetes, heart disease and kidney disease and your overall risk of heart attack or stroke. See heart risk assessment.

Having high blood pressure increases your risk of:

Causes of high blood pressure

A lot of different factors contribute to high blood pressure.

You cannot change some of them, such as getting older, having a family member with high blood pressure and having kidney disease.

Others factors causing high blood pressure include smoking, having too much salt and processed foods, drinking too much alcohol, being overweight, stress and being inactive.

Diagnosing high blood pressure

High blood pressure doesn't usually cause any symptoms. This means it's only found by having a blood pressure check by your doctor, nurse or pharmacist. Rarely, very high blood pressure can cause headaches and problems with vision.

You should have a blood pressure check as part of a heart risk assessment. Heart risk assessment explains who has a higher risk and what age you should start getting your blood pressure checked.

To determine if you have high blood pressure, your GP may want to take several blood pressure measurements on a few separate occasions. This is because your blood pressure normally changes throughout the day. It's lower when you're asleep or relaxing and goes up when you move around. It can also be increased by stress and stimulants like nicotine and caffeine.

In some cases, your GP might suggest:

This is usually done so your doctor can get a better idea of what your usual blood pressure is when you're in a more relaxed setting, and to see what happens at different times of the day.

If you're diagnosed with high blood pressure, you'll have blood and urine tests. This is to check for possible causes and for other risk factors of high blood pressure such as diabetes, kidney disease and high cholesterol.

Treating high blood pressure

You can improve your blood pressure and reduce the risk of complications by following the advice on Self-care for high blood pressure.

If your blood pressure remains too high, your doctor will recommend medications. You may need to take more than one medicine to lower your blood pressure enough.

See Blood pressure medicines for more detailed information about the types of medicines and how to take them.

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Written by HealthInfo clinical advisers. Last reviewed December 2021.

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Review key: HIHBP-25277