High blood pressure (hypertension)

Next review due September 2024

About high blood pressure

Every time your heart beats, it pumps blood under pressure to the rest of your body through your arteries. You need some pressure to keep your blood moving. But if it’s always too high, it puts extra strain on your heart and blood vessels. Other parts of your body, such as your brain and your kidneys may also be affected by high blood pressure. The medical name for high blood pressure is hypertension. Sometimes high blood pressure is caused by another health problem you already have. But most of the time there’s no obvious cause. For more information, see our section on causes.

Blood pressure is measured at two points.

• The highest level (systolic blood pressure). This is when your heart muscle contracts and pumps blood out through the arteries.
• The lowest level (diastolic blood pressure). This is when your heart relaxes between beats and fills with blood.

Your blood pressure is shown as two numbers, measured in millimetres of mercury (mmHg). A reading of around 120/80mmHg is seen as healthy – above 140/90mmHg is considered high.

Symptoms of high blood pressure

Most people with high blood pressure don’t have any symptoms and aren’t aware of their condition. It’s usually found when you have your blood pressure measured. This may be as part of a health assessment. If you have high blood pressure and it causes complications, you may get symptoms linked to those. For more information, see our section on complications.

Diagnosis of high blood pressure

The only way to know if you have high blood pressure is to have it measured. It’s good to get your blood pressure checked at least every five years. You may be able to get this done at your local pharmacy. Everyone should know their blood pressure.

Measuring blood pressure

The latest automated, digital devices make it quick and easy to check your blood pressure. Or your doctor might take a reading using a stethoscope held against your arm to listen to the blood flow. Try to relax – it may be a little uncomfortable but that’s only for a few moments. 

Your doctor or nurse will probably check your blood pressure several times during a visit. If your blood pressure is high, they may recommend you have more readings over a longer period. This helps to make a definite diagnosis. There are two ways to do this.

• You can wear a device on your arm for 24 hours as you carry on normal activities. This is called ambulatory blood pressure monitoring (ABPM). For more information, see our FAQ on 24-hour monitoring.
• You can measure your blood pressure yourself at home for four to seven days. You measure your blood pressure morning and evening, each time after resting for five minutes.

You can buy your own device for measuring your blood pressure at home. 

Further tests

If you have high blood pressure, your doctor will want to find out if there’s a reason for this. They’ll also want to see if it has done any harm, especially to your heart or kidneys.

Your doctor will ask about your general health, any symptoms you have and any medicines you take. They may ask about your family’s medical history. They may also ask about your weight, your diet, whether or not you smoke, and your exercise and drinking habits. They may examine you.

You may be offered further tests, including the following.

• A urine test to check for protein or blood that could be a sign of kidney damage.
• A blood test to check your cholesterol level. This helps to assess your risk of heart disease. It also checks for diabetes, and problems with your kidneys.
• An electrocardiogram (ECG) to see how your heart is working.
• An examination of the back of your eyes with an ophthalmoscope to check if the blood vessels there are healthy.

If your blood pressure is very high (over 180/110mmHg) or your doctor suspects it’s caused by a serious condition, they may refer you to a specialist. They may also refer you to a specialist if you have high blood pressure and you’re under 40. Your specialist may recommend further tests. If so, they’ll explain what these involve.

Causes of high blood pressure

For most people with high blood pressure, there’s no obvious cause. This is called primary hypertension or essential hypertension. Some things increase your risk of getting this type of high blood pressure. These include:

• your age – the risk increases as you get older
• having someone in your close family with high blood pressure
• being overweight or obese
• eating too much salt
• drinking too much alcohol
• not getting enough exercise
• anxiety and stress

Sometimes, high blood pressure is linked to an underlying medical issue. This is called secondary hypertension. Causes of secondary hypertension include:

• kidney disease
• pregnancy
• hormone disorders such as an underactive or overactive thyroid, or a tumour of the adrenal gland
• obstructive sleep apnoea (frequent pauses in breathing when you sleep)

Treatment of high blood pressure

There are several things your doctor will consider in deciding how best to treat you. These include:

• your age
• your ethnic group 
• any other medical conditions you have
• your risk of heart disease and stroke
• the possible causes of your high blood pressure
• how high your blood pressure is

Lifestyle changes

Your doctor will encourage you to make lifestyle changes to help reduce your blood pressure. These include the following.

• Lose excess weight . Aim to reduce your waist to under 102cm (40 inches) if you’re a man, and under 88cm (35 inches) if you’re a woman. Our video below shows you how to measure your waist. You should also aim to get your BMI (body mass index) down to 25 or less. You can find out your BMI using our BMI calculator.
• Eat a healthy balanced diet
• Eat less salt – you should have less than 5g (one teaspoon) a day.
• Be more physically active
• Stick to recommended guidelines on how much alcohol you drink.
• Drink less coffee and other caffeinated drinks like cola.
• Try to improve how well you sleep.

Stress can make your blood pressure go up, so learn how to manage stress.Stopping smoking may not have a direct impact on your blood pressure, but it reduces the risk of complications like heart disease and stroke.

Medicines

There are several medicines that can lower your blood pressure. Your GP may start you on a combination of two medicines. It can take time to find the medicines that work for you.

The medicines most commonly used to treat high blood pressure are listed here.

• Angiotensin-converting enzyme inhibitors ( Angio(ACE inhibitors)   such as ramipril or lisinopril relax and widen blood vessels.
• (ARBs) such as candesartan, losartan or valsartan work in a similar way to ACE inhibitors.
• (CCBs) such as amlodipine or diltiazem relax and widen your arteries so your heart receives a better blood supply. This means it needs to do less work to pump blood round your body.
• Thiazide diuretics such as bendroflumethiazide and indapamide make your kidneys produce more urine. This reduces the amount of fluid in your blood.

If these aren’t suitable for you or if they don’t work well enough, your doctor may prescribe other medicines to treat your high blood pressure. For instance, sometimes beta-blockers may be suitable. However, these are no longer one of the main treatments for high blood pressure.

Always carefully read the information that comes with your medicines. If you have any questions about taking them, ask your doctor Your doctor may suggest you regularly monitor your blood pressure at home as part of your treatment.

Complications of high blood pressure

Although having high blood pressure does not usually cause any symptoms, it does increase your risk of getting complications. These include:

• coronary heart disease (including angina and heart attack)
• a stroke
• heart failure
• kidney disease
• peripheral artery disease
• problems with your vision
• vascular dementia

These problems usually take many years to develop. With medicines and lifestyle changes, you can reduce the risk of them ever happening.

Special considerations for high blood pressure

Diabetes

High blood pressure is a particular issue if you have diabetes. Both hypertension and diabetes increase the risk of kidney disease and cardiovascular disease. If you have diabetes, you should get your blood pressure measured at least once a year.

Pregnancy

If you’re pregnant, you’ll have your blood pressure checked regularly. Having high blood pressure during pregnancy may cause problems for you and your baby. It may be a sign of a condition called pre-eclampsia.

If you’re on medicines for high blood pressure and you get pregnant, your doctor may suggest changing your medicines.