About high blood pressure

High blood pressure, also known as hypertension, is usually defined as having a sustained blood pressure of 140/90mmHg or above.

The line between normal and raised blood pressure is not fixed and depends on your individual circumstances. However, most doctors agree that the ideal blood pressure for a physically healthy person is around 120/80mmHg.

A normal blood pressure reading is classed as less than 130/80mmHg.

The heart (blood pump)

The heart is a muscle that is designed to constantly pump blood around the body. It pumps blood that is low in oxygen towards the lungs, through the venous 'pipeline' (veins), where it receives a fresh supply of oxygen.

Once the blood is fully oxygenated, the heart pumps the oxygen-rich blood around the body so that the oxygen can be used by the body’s muscles and cells, through the arterial 'pipeline' (arteries).

How is blood pressure measured?

Blood pressure is defined as the amount of pressure that is exerted on the artery walls as blood moves through them. It is measured in millimetres of mercury, or mmHg.

A more detailed explanation is provided below.

Two measurements are used to measure blood pressure:

  • Systolic pressure - the measure of blood pressure exerted when your heart beats and forces blood around your body.
  • Diastolic pressure - the measure of blood pressure when your heart is resting in between beats.

Both the systolic and diastolic pressures are measured in millimetres of mercury (mmHg).

The figures are usually represented with the systolic pressure first, followed by the diastolic pressure. Therefore, if your GP says that your blood pressure is '120 over 80', or 120/80mmHg, they mean that you have a systolic pressure of 120mmHg and a diastolic pressure of 80mmHg.

More about the diagnosis of high blood pressure

Symptoms of high blood pressure

High blood pressure often causes no symptoms, or immediate problems.

The only way to find out whether you have high blood pressure is to have your blood pressure checked regularly. Ask your GP when you are next due for yours to be checked.

Find out more about the symptoms of high blood pressure

How common is high blood pressure?

High blood pressure is a common condition, it is estimated that 18% of adult men and 13% of adult women have high blood pressure but are not getting treatment for it.

In 90-95% of cases, there is no single identifiable reason for a rise in blood pressure. But all available evidence shows that lifestyle plays a significant role in regulating your blood pressure.

Risk factors for high blood pressure include:

  • age (the risk of developing high blood pressure increases with age. Half of people over 75 years have the condition.)
  • poor diet
  • lack of exercise
  • being overweight
  • excessive alcohol consumption.

Also, for reasons not fully understood, people of Afro-Caribbean and South Asian origin (Indian, Pakistani, and Bangladeshi) are more likely to develop high blood pressure than other ethnic groups.

More about the causes of high blood pressure and how high blood pressure is prevented

What's the impact of having high blood pressure?

High blood pressure is a major risk factor for developing cardiovascular diseases such as:

  • coronary heart disease - where the main arteries that supply your heart (the coronary arteries) become clogged up with plaques (fatty deposits)
  • strokes - a serious condition where the blood supply to your brain is interrupted
  • heart attacks - a serious condition where the blood supply to part of your heart is blocked

Diabetes and kidney disease are also linked to high blood pressure complications.

More about complications of high blood pressure

Treatment and prevention of high blood pressure

High blood pressure can be managed or controlled by making changes to your lifestyle, such as:

  • eating a healthier diet
  • exercising more regularly
  • reducing the amount of alcohol that you drink.

Medication that can help you lower your blood pressure is also available.

More about the treatment of high blood pressure

Symptoms of high blood pressure

High blood pressure does not usually cause any obvious symptoms. Symptoms can occur in rare cases where a person has a very high blood pressure level so it is good to be aware of these.

The symptoms may include:

  • headaches
  • blurred or double vision
  • regular nosebleeds
  • shortness of breath

Visit your GP as soon as possible if you have any of these symptoms.

Regular blood pressure checks for over over 40's

The only way to find out whether you have high blood pressure is to have your blood pressure checked regularly. Ask your GP when you are next due for yours to be checked.

Blood pressure checks are usually available on request at most GP surgeries and health clinics. Some surgeries have home monitoring devices available, which you may be able to use at the time of blood pressure medication start up or change. Many also have a policy of arranging regular checks for you.

Adults who are over 40 and have not been diagnosed with high blood pressure should have their blood pressure checked at least once every five years. However, your blood pressure should ideally be checked more frequently, particularly if you have any contributory risk factors.

Regular blood pressure checks if diagnosed with high blood pressure

If you are diagnosed with high blood pressure, your blood pressure will need to be closely monitored until it is brought under control.

After your blood pressure has been controlled, your GP or practice nurse will measure your blood pressure at agreed regular intervals (at least once a year).

It is important you attend these appointments to ensure your blood pressure is being maintained within an acceptable range.

Blood pressure checks during pregnancy

If you are pregnant, you should have your blood pressure checked on a regular basis, even if it is not high.

Watching your blood pressure while you are pregnant reduces your risk of developing pregnancy-induced hypertension. This can lead to a serious condition called pre-eclampsia where there is a problem with the placenta (the organ that links the baby’s blood supply to the mother’s).

Causes of high blood pressure

There are two types of high blood pressure:

  • Primary high blood pressure (also known as essential high blood pressure) - has no identifiable cause.
  • Secondary high blood pressure - is related to an underlying cause, such as kidney disease, or a particular type of medication that you are taking.

You can find out more about each of these below.

Primary high blood pressure

While the specific cause of primary high blood pressure remains unknown, there is compelling evidence to suggest that a number of risk factors increase your chances of developing the condition. 

These risk factors include:

  • age - the risk of developing high blood pressure increases as you get older
  • a family history of high blood pressure - the condition seems to run in families
  • being of Afro-Caribbean or South Asian origin
  • high-fat diet
  • high amount of salt in your diet
  • lack of exercise
  • being overweight
  • smoking
  • excessive alcohol consumption
  • stress

A number of health conditions, such as diabetes and kidney disease, have also been linked to an increase risk of developing primary high blood pressure.

Secondary high blood pressure

Some cases of high blood pressure (between 5 and 10%) are the result of underlying factors or cause and this is known as secondary high blood pressure. 

Underlying factors include:

  • kidney conditions, such as a kidney infection, or kidney disease
  • narrowing of the arteries (pipeline taking blood round the body from the heart)
  • hormonal conditions, such as Cushing's syndrome (a condition where your body produces an excess of steroid hormones)
  • conditions that affect the body’s tissue, such as lupus (a condition where the immune system attacks healthy tissue)
  • medication, such as the oral contraceptive pill, or the type of painkillers that are known as nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
  • excessive alcohol consumption
  • recreational drugs, such as cocaine, amphetamines and crystal meth

Occasionally, a rise in blood pressure can result from taking herbal remedies, such as herbal supplements.

Diagnosing high blood pressure

The only way to find out whether you have high blood pressure is to have your blood pressure checked regularly. Ask your GP when you are next due for yours to be checked.

Before having your blood pressure taken, you should rest for at least five minutes and empty your bladder. To get an accurate blood pressure reading, you should be sitting down and not talking when the reading is taken.

Having one high blood pressure reading does not necessarily mean that you have high blood pressure. Your blood pressure can change throughout the day. Feeling anxious or stressed when you visit your GP can raise your blood pressure (often referred to as ‘white coat syndrome’).

Therefore, your GP will need to take several readings over a set period of time, usually every month, to see whether your blood pressure level is consistently high.

Blood and urine tests may also be carried out in order to check for conditions that are known to cause an increase in blood pressure, such as kidney infections.

You may also be given a blood pressure device to take home so that you can record your blood pressure level throughout the day. This also helps to identify white coat syndrome and therefore helps to identify the best treatment options for you.


Blood pressure is traditionally measured using a device known as a sphygmomanometer. This device uses an inflatable cuff and has a scale of mercury, like a thermometer.

Your pulse is heard by the health professional taking your blood pressure, through a stethoscope placed on your artery.

Digital sphygmomanometer 

Many GP surgeries now use digital, or semi automatic, sphygmomanometers which measures your pulse using electrical sensors in a cuff that is usually placed around your upper arm.

The cuff is pumped up to restrict the blood flow in your arm, before slowly being released. 

Digital blood pressure device

Digital blood pressure devices are now commercially available. Blood pressure testing kits are also commercially available. 

Treating high blood pressure

Treatment for high blood pressure will depend on your blood pressure levels and your associated risk (after taking account of several factors) of developing a cardiovascular disease, such as a heart attack or stroke.

There are seven main risk factors for developing a cardiovascular disease. These are:

  • age
  • high blood pressure
  • smoking (or a previous history of smoking)
  • obesity
  • lack of exercise
  • having a high level of cholesterol in your blood
  • having a family history of cardiovascular disease (conditions of the heart or blood vessels).

If your blood pressure is slightly high

If your blood pressure is slightly higher than the ideal level (120/80mmHg), and your GP feels that the risks of cardiovascular disease are low, then you should be able to lower your blood pressure by making simple lifestyle changes (see more below).

If your blood pressure is moderately high 

If your blood pressure is moderately high (140/90mmHg or higher), or your GP feels that your risk of developing cardiovascular disease in the next 10 years is more than one in five, then you will be advised about changing your lifestyle and may also be prescribed medication.

If your blood pressure is very high 

If your blood pressure is very high (180/110 mmHg or above) you should be referred to a hypertension specialist (a doctor who specialises in treating high blood pressure). 

Lifestyle changes

The following lifestyle changes are known to reduce high blood pressure:

  • regular exercise of at least 30 minutes a day, a minimum of five times a week (e.g. walking, cycling or swimming)
  • cutting your alcohol intake to recommended levels (less than 21 units a week for men, and less than 14 units a week for women)
  • eating a healthy, low-fat, balanced diet, and restricting your salt intake to less than 6g (0.2oz) a day
  • losing weight if you are overweight or obese
  • restricting your caffeine consumption to less than five cups of coffee or tea a day
  • relaxation therapies, such as yoga and meditation

Even if you achieve a relatively low decrease in your blood pressure, it can still have significant health benefits.

More about preventing high blood pressure


A number of medications can be used to treat high blood pressure. You may need to take more than one type of medication to lower your blood pressure because a combination of treatments is sometimes needed to successfully treat the condition.

If you have high blood pressure, you may need to take blood pressure-lowering medication for the rest of your life. However, if your blood pressure levels stay under control for several years, you should ask your GP if you could come off your treatment and have your blood pressure monitored.

Most medications that are used to treat high blood pressure have some side effects (see below for details of the specific side effects of each type of medication). Consult your GP immediately if you have any of the following common side effects while taking medication for high blood pressure:

  • feeling drowsy
  • pain around your kidney area (on the side of your lower back)
  • a dry cough
  • dizziness, faintness or light-headedness
  • a skin rash

Research has shown that different blood pressure lowering medications work better for different ethnic groups. For example, ACE inhibitors are more effective as a first-choice medication for treating high blood pressure in white people, whereas calcium channel blockers, or thiazide diuretics, tend to work better for black people.

It is thought that this is because black people tend to have a lower level of renin in their blood. Renin is an enzyme that helps to regulate blood pressure. ACE inhibitors are most effective when there is a high amount of renin in the blood, so they are not as effective in treating black people with high blood pressure.

Therefore, your GP will consider your ethnic background when making a treatment plan.

The most widely used medications for treating high blood pressure are described below:

  • Angiotensin-converting enzyme (ACE) inhibitors 
  • Calcium channel blockers
  • Thiazide diuretics
  • Alpha-blockers
  • Beta-blockers

Angiotensin-converting enzyme (ACE) inhibitors 

Angiotensin-converting enzyme (ACE) inhibitors work by blocking the actions of some of the hormones that help to regulate blood pressure. 

By stopping these hormones from working, the medication helps to reduce the amount of water in your blood, and it widens your arteries, decreasing your blood pressure.

ACE inhibitors are not suitable for:

  • pregnant or breastfeeding women
  • people with conditions that affect the blood supply to their kidneys

ACE inhibitors have been known to reduce the blood supply to the kidneys, which can reduce their efficiency. Therefore, blood and urine tests may be carried out before you start taking ACE inhibitors to make sure that there are no pre-existing problems with your kidneys.

You may need to have annual blood and urine tests if you continue to use ACE inhibitors.

Side effects of ACE inhibitors include:

  • dizziness
  • tiredness or weakness
  • headaches
  • a persistent dry cough

Most of these side effects should pass in a few days, although some people find that they continue to have a dry cough.

If side effects become particularly troublesome, a medication that works in a similar way to ACE inhibitors, known as an angiotensin-2 receptor antagonist, may be recommended.

ACE inhibitors can cause unpredictable effects if taken with other medications, including some over-the-counter (OTC) ones. Therefore, as with any prescribed medication always check with your GP or pharmacist before taking any 'over the counter' medication in combination with those prescribed for you.

Calcium channel blockers

Calcium channel blockers work by relaxing the muscles that make up the walls of your arteries. This widens your arteries and reduces your blood pressure.

Examples of calcium channel blockers include:

  • Diltiazem
  • Verapamil
  • Amolodipine
  • Nifedipine

Every calcium channel blocker acts differently. Common side effects of calcium channel blockers should pass within a few days once your body gets used to the medication, these include:

  • flushed face
  • headaches
  • swollen ankles
  • dizziness
  • tiredness
  • skin rashes
  • abnormally fast, slow or uneven heart rate

Certain brands of calcium channel blocker may also cause constipation in some people.

Do not drink grapefruit juice if you are taking calcium channel blockers because it can lower your blood pressure.

Thiazide diuretics

Thiazide diuretics, work by reducing the amount of water in your blood and widening the walls of your arteries. They are not recommended for pregnant women, or people who have gout (a type of arthritis where crystals develop inside the joints).

Thiazide diuretics have been known to reduce the level of potassium in your blood, which can interfere with your heart and kidney functions. They can also raise the level of sugar in your blood, which could lead to diabetes.

Therefore, you will probably be recommended to have blood and urine tests every six months so that your potassium and blood sugar levels can be monitored.

Example of thazide diuretics include: 

  • Bendrofluazide
  • Furosemide
  • Torasemide

The side effects of thiazide diuretics include:

  • dizziness
  • nausea
  • muscle cramps
  • going to the toilet more during the day and possibly night

A few people have reported that they could not get or maintain an erection while taking thiazide diuretics. However, this particular side effect was resolved once the medication was withdrawn.

There are two other types of diuretic available which you may be prescribed these are:

  • Loop Diuretics
  • Potassium-sparing diuretics


Alpha-blockers are effective in reducing high blood pressure. However, they are not usually prescribed unless you are already taking other medication and your blood pressure is still high.

Alpha-blockers, work by preventing the muscles that line your blood vessels (alpha receptors) from being activated and tightening the muscles in the walls of your blood vessels. This enables the blood vessels to relax and open, making it much easier for blood to flow through them and lower your blood pressure.

Examples of alpha-blockers include: 

  • Tolazoline
  • Doxasosin
  • Trazodone

Common side effects of alpha-blockers include:

  • fainting spells when you first start the treatment
  • dizziness
  • headache
  • swollen ankles
  • tiredness


Beta-blockers used to be a popular treatment for high blood pressure, but now they only tend to be used when other treatments have not proved successful. This is because beta-blockers have more potential side effects than the other medications that are used to treat high blood pressure.

Beta-blockers, work by slowing down your heart rate and the force of your heart. This reduces the pressure at which the blood is pumped out of your heart and around your body.

Examples of beta-blockers include: 

  • Atenolol
  • Bisoprolol
  • Carvedilol
  • Sotolol
  • Propranolol.

Common side effects of beta-blockers include:

  • tiredness
  • nausea
  • cold hands and feet
  • slow heartbeat
  • diarrhoea

Less common side effects of beta-blockers include:

  • sleep disturbances
  • nightmares
  • impotence

Although beta-blockers are not the preferred method of treatment for high blood pressure, they may be considered for younger people if:

  • other treatments, such as ACE inhibitors, have not been effective
  • a woman is fertile (can become pregnant)

Beta-blockers can also interact with other medications, causing possible adverse side effects. Therefore, as with any prescribed medication always check with your GP or pharmacist before taking any 'over the counter' medication in combination with those prescribed for you 

Do not suddenly stop taking beta-blockers without first consulting your GP. Stopping this medication suddenly will lead to serious side effects, such as a rise in blood pressure or chest pain caused by reduction in oxygen to your heart muscle (angina).

Complications of high blood pressure

If left untreated, high blood pressure can cause many different types of cardiovascular disease. 

For example:

  • stroke - a serious condition where the blood supply to the brain is interrupted
  • heart attack - a serious condition where the blood supply to part of the heart is blocked
  • blood clot (thrombosis) - a serious condition that is caused by blood clots within the blood vessels
  • aneurysm - a serious condition that is caused by a weakness in the blood vessel wall, which forms a bulge in the blood vessel

Kidney disease

High blood pressure can damage the small blood vessels in your kidneys and stop them from working properly. 

This can cause a number of symptoms, including:

  • tiredness
  • swollen ankles, feet or hands (due to water retention)
  • shortness of breath
  • blood and/or protein in your urine
  • urinating more often, particularly at night (nocturia)
  • itchy skin

Kidney disease can be treated using a combination of medication and dietary supplements. Cases that are more serious may require dialysis (a treatment where waste products are artificially removed from the body) or a kidney transplant.

More about chronic kidney disease

Preventing high blood pressure

The best ways to prevent high blood pressure and the associated risks of cardiovascular disease are to:

  • eat a healthy diet
  • maintain a healthy weight
  • exercise regularly
  • drink alcohol in moderation only
  • drink caffeine in moderation only
  • avoid smoking.

You can find out more about each of these below.

Eat a healthy diet

A low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day) and whole grains.

Limit the amount of salt that you eat to no more than 6g (0.2oz) a day. Too much salt will increase your blood pressure (6g of salt is about one teaspoonful).

Avoid foods that are high in saturated fat as this will increase your cholesterol level, which is another risk factor for cardiovascular disease.

Foods that are high in saturated fat include:

  • meat pies
  • sausages and fatty cuts of meat
  • butter
  • ghee (a type of butter that is often used in Indian cooking)
  • lard
  • cream
  • hard cheese
  • cakes and biscuits
  • foods that contain coconut or palm oil

However, eating some foods that are high in unsaturated fat can actually decrease your cholesterol level.

Foods that are high in unsaturated fat include:

  • oily fish
  • avocados
  • nuts and seeds
  • sunflower oil, rapeseed oil and olive oil

More about eating a healthy balanced diet

Maintain a healthy weight

Being overweight is a risk factor for having high blood pressure, and your risk increases further if you are obese.

There are two ways to check if you are overweight:

  • Body Mass Index (BMI) - This is your weight in kilograms divided by your height in metres squared. In the UK, people with a BMI of between 25 to 30 are overweight, and those with an index above 30 are classed as obese. People with a BMI of 40 or more are morbidly obese. 
  • Waist size - Using a measuring tape place the tape round your waist between the bottom of your ribs and the top of your hip bone. The table below indicates how much your health might be at risk, your ethnicity should also be taken into account. 
Sex Ethnicity Waist size (increased risk) Waist size (severe risk)
Male   Over 94 cm (37 inches) Over 102 cm (40 inches)
Male South Asian   Over 90 cm (35.5 inches)
Female   Over 80 cm (32 inches) Over 88 cm (35 inches)
Female South Asian   Over 80 cm (32 inches)

The best way to tackle obesity is by reducing the amount of calories that you eat, and taking regular exercise. Your GP can provide you with further information and advice on how you can do this.

More about having a healthy weight


Exercise can raise your blood pressure at time of doing it but regular exercise at the right level for you can help to reduce your blood pressure and maintain a lower level.

The following information provides general advice about blood pressure and exercise:

  • Below 90/60 - You may have low blood pressure, speak to your doctor or nurse before starting any new exercise
  • 90/60 to 140/90 - It is safe to be more active, and it will help to keep your blood pressure in this the ‘ideal’ blood pressure range
  • 140/90 to 179/99 - It should be safe to start increasing your physical activity to help lower your high blood pressure
  • 180/100 to 199/109 - Speak to your doctor or nurse before starting any new exercise
  • 200/110 or above - Do not start any new activity, speak to your doctor or nurse.

More about keeping active

Drink alcohol in moderation

Drinking excessive amounts of alcohol will increase your blood pressure and raise the cholesterol levels in your blood.

Sticking to the recommended amounts of alcohol consumption is the best way to reduce your risk of developing high blood pressure.

The recommended daily limits of alcohol consumption are:

  • 3 to 4 units of alcohol for men
  • 2 to 3 units of alcohol for women.

A unit of alcohol is equal to about half a pint of normal-strength lager, a small glass of wine or a pub measure (25ml) or spirits.

More about drinking alcohol responsibly

Drink caffeine in moderation

It is important to restrict your daily intake of coffee or drinks that contain caffeine, such as soft drinks and cola.

Your blood pressure may increase if you drink more than four cups of coffee a day.

Stop smoking

If you smoke, there is plenty of help and support available to help you quit.

Find out some effective ways to stop smoking

Last updated:
14 April 2023