High blood pressure (hypertension)

This factsheet is for people who have high blood pressure (hypertension), or who would like information about it.

Blood pressure is a measure of the force that the blood applies to the walls of the arteries as it flows through them. It's normal for blood pressure to increase when you exert yourself, or when you feel stressed or anxious. But if your blood pressure is consistently higher than the healthy level when at rest, this is high blood pressure (hypertension).

Having your blood pressure taken
About high blood pressure
Symptoms of high blood pressure
Complications of high blood pressure
Causes of high blood pressure
Diagnosis of high blood pressure
Treatment of high blood pressure
Special considerations of high blood pressure

Having your blood pressure taken

About high blood pressure

Blood carrying oxygen and nutrients is pumped around your body by your heart. The blood is under pressure as a result of the pumping action of your heart and the size and flexibility of your arteries, which carry the blood. This blood pressure is an essential part of the way your body works.
You can get high blood pressure if the walls of your arteries lose their elasticity, become narrowed or contract too much, if your heart is pumping too much blood or if you have too much blood in circulation.  
About three in 10 adults in the UK have high blood pressure. It's much more common in older people – seven out of 10 people over 75 have high blood pressure.

Symptoms of high blood pressure

Most people with high blood pressure don't have any symptoms.
If you have very high blood pressure, or your blood pressure rises quickly, you may have headaches, problems with your vision, fits or black-outs.

Complications of high blood pressure

If you have high blood pressure, you have an increased risk of major illnesses including:

•    cardiovascular disease, such as angina (chest pain caused by reduced blood flow), stroke, heart attack, heart failure or atrial fibrillation (irregular heart beat)
•    kidney damage
•    damaged sight

Causes of high blood pressure

Primary hypertension

More than nine in 10 people with high blood pressure have what is called primary or essential hypertension. This means that it has no single clear cause.

Many factors to do with your lifestyle may contribute to primary hypertension. These include:

•    smoking
•    obesity (being very overweight)
•    drinking a lot of alcohol – especially if you binge drink
•    lack of exercise
•    your diet

If someone else in your family has high blood pressure, you also have a higher risk of developing it.

Secondary hypertension

Around one in 20 people with high blood pressure have secondary hypertension. This means your doctor can link your high blood pressure to a known cause:
•    kidney disease
•    endocrine disease (hormone disorders – a hormone is a regulatory chemical that occurs naturally in your body)
•    a narrowing of the aorta (the largest artery leading from the heart) or the arteries leading to the kidneys

Secondary hypertension can also be caused by:
•    steroid medicines
•    the contraceptive pill
•    pregnancy, which can cause pre-eclampsia – this can be serious and harm your baby

Diagnosis of high blood pressure

You may not have any symptoms, so your GP may diagnose high blood pressure when he or she takes your blood pressure as part of a medical examination. That's one good reason to have a regular check-up with your GP, especially if you're over 40.

Your GP or nurse will measure your blood pressure with a monitor called a sphygmomanometer. He or she will place a cuff around your upper arm and will inflate it to a certain level and then deflate it slowly.

The result is expressed as two numbers, such as 120/80mmHg (one hundred and twenty over eighty millimetres of mercury).

•    The first figure – the systolic blood pressure – is a measure of the pressure when your heart muscle is contracted and pumping blood. This is the highest pressure in your blood vessels.
•    The second figure – the diastolic blood pressure – is the pressure between heart beats when your heart is resting and filling with blood. This is the lowest pressure in your blood vessels.

The lower your blood pressure, the better for your health. Doctors recommend that your blood pressure is kept below 140/85. If you have diabetes or cardiovascular disease, your blood pressure should be lower than this – ideally less than 130/80. If your blood pressure is around this level, your GP will probably want to monitor it.

Your GP may ask you to come back for repeat measurements over a number of weeks before suggesting that you have treatment. This is so he or she can check that the high reading is an ongoing problem and not a one-off.

You may also need some tests to see if high blood pressure is affecting the rest of your body. These may include:
•    a urine test – protein in your urine may be the first sign of a kidney problem
•    a blood test to check your cholesterol and blood sugar levels, as well as the condition of your kidneys
•    an electrocardiogram (ECG) – a test that measures the electrical activity of your heart to see how well it's working

Monitoring

You may be given a 24-hour monitoring if your GP thinks you may get ‘white coat’ hypertension – high blood pressure when a doctor or nurse measures it, or to find out what your blood pressure is overnight. A monitoring device is strapped round your waist and attached to a cuff wrapped around your upper arm. The cuff inflates and deflates automatically throughout the 24 hours and takes recordings of your blood pressure.

You might consider getting a blood pressure monitor to use yourself at home – discuss this with your GP. The British Hypertension Society (see Further information) can give you a list of clinically validated blood pressure monitors.

It's important to take readings on different days – for example you shouldn't just measure your blood pressure when you feel stressed. Set days in the week to take the measurement so that you can get a consistent reading.

You should continue to have your blood pressure tested regularly by your GP, even if you use a blood pressure monitor at home.

Treatment of high blood pressure

You're likely to need long-term treatment for high blood pressure because it can’t usually be cured.
If you have very high blood pressure, you may need to go to hospital for treatment. But it's much more likely that your GP and/or a nurse will look after you.

Self-help

Your GP or nurse will talk to you about lifestyle changes which might help. For example, he or she will advise you to:
•    stop smoking
•    change your diet to a low-fat, low-salt diet that includes fruit and vegetables
•    cut down on alcohol
•    cut down on coffee and high-caffeine drinks, such as cola
•    take some regular, moderate exercise
•    lose any excess weight
It may also help to try to reduce the stress in your life to prevent short-term rises in blood pressure – try relaxation techniques or meditation.

Medicines

If your blood pressure stays high, your GP may prescribe you one or more of the following antihypertensive medicines.

•    ACE inhibitors (eg ramipril) or angiotensin-II receptor antagonists (eg candesartan cilexetil) – these relax and widen the walls of your blood vessels by reducing the production of hormones that cause your blood vessels to tighten.
•    Calcium-channel blockers (eg amlodipine) – these help to widen your blood vessels by relaxing the muscles in your blood vessel walls.
•    Diuretics (eg bendroflumethiazide) – these increase the amount of water and salt removed from your blood by your kidneys – lowering the volume of your blood which reduces blood pressure.
If your symptoms don’t improve after other medicines, then your GP may prescribe one of the following:
•    Beta-blockers (eg atenolol) – these reduce the work your heart has to do by reducing your pulse rate and the force of contraction of your heart at rest and when you exercise.
•    Alpha-blockers (eg doxazosin) – these help to widen your blood vessels by relaxing the muscles in the blood vessel walls.

The medicines your GP prescribes will depend on a number of factors, including your age and ethnicity. It may take time to find the best treatment for you; one that balances benefits against any side-effects.

It's important to take your medicines every day even if you don't have any symptoms of high blood pressure.

Special considerations of high blood pressure

Pregnancy

If you're pregnant your blood pressure is monitored regularly, whether you have hypertension or not. Long-term high blood pressure may be picked up at an antenatal appointment. It's also possible that you may develop high blood pressure during your pregnancy (gestational hypertension). High blood pressure that develops after 20 weeks of pregnancy can mean you have pre-eclampsia, which can be harmful for you and your baby.

If you have high blood pressure and think you may be, or are trying to become pregnant, it's important that you tell your GP. Certain medicines for treating high blood pressure aren't suitable for pregnant women.

Ethnic groups

If you're of African-Caribbean origin, you're at a higher risk of hypertension and you should visit your GP for regular monitoring.

You should also be monitored regularly if you're of South Asian origin because you have a higher risk of developing heart disease and diabetes.