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19 min read

High blood pressure (hypertension)

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Known as the "silent killer", high blood pressure rarely has obvious symptoms.

The only way of knowing there's a problem is to have your blood pressure measured.

All adults should have their blood pressure checked at least every 5 years. If you haven’t had yours measured, or you don’t know what your blood pressure reading is, ask your doctor to check it for you.

What is high blood pressure?

Blood pressure measures how strongly blood presses against the walls of your arteries (large blood vessels) as it's pumped around your body by your heart. If this pressure is too high it puts a strain on your arteries and your heart, which makes it more likely that you'll suffer a heart attack, a stroke or kidney disease.

Blood pressure is measured in millimetres of mercury (mmHg) and it's recorded as two figures:

  • systolic pressure: the pressure of the blood when your heart beats to pump blood out
  • diastolic pressure: the pressure of the blood when your heart rests in between beats

For example, if your doctor says your blood pressure is "140 over 90", or 140/90mmHg, it means you have a systolic pressure of 140mmHg and a diastolic pressure of 90mmHg.

You're said to have high blood pressure (hypertension) if readings on separate occasions consistently show your blood pressure to be 140/90mmHg or higher.

A blood pressure reading below 130/80mmHg is considered to be normal.

Who's most at risk?

Your chances of having high blood pressure increase as you get older. There's often no clear cause of high blood pressure but you're at increased risk if you:

  • are overweight
  • have a relative with high blood pressure
  • are of African or Caribbean descent
  • eat a lot of salt
  • don't eat enough fruit and vegetables
  • don't do enough exercise
  • drink a lot of coffee (or other caffeine-based drinks)
  • drink a lot of alcohol
  • are over 65 years old

If you fall into any of the groups listed above, consider making changes to your lifestyle to lower your risk of high blood pressure. Also consider having your blood pressure checked more often, ideally about once a year.

Prevention and treatment

You can take steps to prevent high blood pressure by:

  • losing weight if you need to
  • exercising regularly
  • eating a healthy diet
  • cutting back if you drink a lot of alcohol
  • stopping smoking
  • cutting down on salt and caffeine

Find out more about how to prevent high blood pressure.

If your blood pressure is found to be high, it will need to be closely monitored until it's brought under control. Your doctor will usually suggest changes to your lifestyle and, sometimes, medication to achieve this.

High blood pressure symptoms

High blood pressure usually has no obvious symptoms and many people have it without knowing.

Untreated high blood pressure can lead to serious diseases, including stroke and heart disease. The only way to know if you have high blood pressure (hypertension) is to have your blood pressure measured. All adults should get their blood pressure checked at least once every 5 years.

In some rare cases, where a person has very high blood pressure, they can experience symptoms including:

  • a persistent headache
  • blurred or double vision
  • nosebleeds
  • shortness of breath

Visit your doctor as soon as possible if you find that you have any of these symptoms.

Causes of high blood pressure

In over 90% of cases, the cause of high blood pressure (hypertension) is unknown but several factors can increase your risk of developing the condition.

Where there's no specific cause, high blood pressure is referred to by doctors as primary high blood pressure (or essential high blood pressure).

Factors that can raise your risk of developing primary high blood pressure 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 African or Caribbean origin
  • a high amount of salt in your food
  • a lack of exercise
  • being overweight
  • smoking
  • drinking large amounts of alcohol
  • stress

Known causes

About 10% of high blood pressure cases are the result of an underlying condition or cause. These cases are referred to as secondary high blood pressure.

Common causes of secondary high blood pressure include:

  • kidney disease
  • diabetes
  • narrowing of the arteries (large blood vessels) supplying the kidneys
  • 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
  • oral contraceptive pill
  • painkillers known as non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
  • recreational drugs, such as cocaine, amphetamines and crystal methamphetamine
  • herbal remedies, such as herbal supplements

Diagnosing high blood pressure

The only way to know if you have high blood pressure (hypertension) is to have your blood pressure checked.

This can be done by your doctor or another healthcare professional, and you can also check it yourself with a home testing kit.

If you're at an increased risk of high blood pressure, you should have your blood pressure checked more often, ideally once a year.

Getting checked by your doctor

Blood pressure checks are usually available on request at most doctor surgeries and health clinics.

Blood pressure is often measured using a sphygmomanometer, a device which consists of a stethoscope, arm cuff, dial, pump and valve.

The cuff is placed around your arm and pumped up to restrict the blood flow. The pressure is then slowly released as your pulse is checked using the stethoscope.

Hearing how your pulse beats after the cuff is released allows a measurement to be taken on the mercury scale, giving an accurate reading of your blood pressure.

Many doctors surgeries now use digital sphygmomanometers, which measure your pulse using electrical sensors.

Before having your blood pressure taken, you should rest for at least 5 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.

Blood pressure readings

Having one raised blood pressure reading does not necessarily mean you have high blood pressure. Blood pressure can fluctuate throughout the day. Feeling anxious or stressed when you visit your doctor can raise your blood pressure.

You'll probably be given a blood pressure kit to take home so you can monitor your blood pressure level throughout the day. This will confirm whether you have consistently high blood pressure.

You may also have blood and urine tests to check for conditions that are known to cause an increase in blood pressure, such as kidney disease.

Home testing kits

Portable testing kits that measure your blood pressure at home or on the move can be a useful way of getting a more accurate reading.

This is because some people become anxious in medical clinics, which can cause the blood pressure to rise. This is a condition called white coat hypertension.

Home or portable blood pressure monitoring kits may show that your blood pressure is in fact normal when you are relaxed.

You can buy a variety of testing kits so you can monitor your blood pressure at home or while you're out and about.

It is important to buy a blood pressure monitor that's reliable and gives accurate readings.

Understanding your reading

Blood pressure measures how strongly blood presses against the walls of your arteries (large blood vessels) as it's pumped around your body by your heart.

It's measured in millimetres of mercury (mmHg) and it is recorded as two figures:

  • systolic pressure: the pressure of the blood when your heart pushes blood out
  • diastolic pressure: the pressure of the blood when your heart rests in between beats

For example, if your doctor says your blood pressure is "140 over 90" or 140/90mmHg, it means you have a systolic pressure of 140mmHg and a diastolic pressure of 90mmHg.

Ideally, your blood pressure reading should be below 120/80mmHg. However, anything under 130/80mmHg is generally considered normal.

You're said to have high blood pressure if readings on separate occasions consistently show your blood pressure to be 140/90mmHg or higher.

If you have kidney disease, diabetes or a condition that affects your heart and circulation, your target blood pressure should be below 130/80mmHg.

Treatment for blood pressure

You can take effective steps to lower your blood pressure with changes to your lifestyle and by taking medication.

Your choice of treatment will depend on your blood pressure level and your risk of developing a cardiovascular disease, such as a heart attack or stroke.

  • if your blood pressure is slightly above 130/80mmHg but your risk of cardiovascular disease is low, you should be able to lower your blood pressure by making some changes to your lifestyle
  • if your blood pressure is moderately high (140/90mmHg or above) and you're at risk of cardiovascular disease in the next 10 years – treatment will involve medication and lifestyle adjustments
  • if your blood pressure is very high (180/110mmHg or above) you will need treatment soon, possibly with further tests, depending on your health

Lifestyle changes

Below are some changes you could make to your lifestyle to reduce high blood pressure. Some of these will lower your blood pressure in a matter of weeks, others may take longer.

  • cut your salt intake to less than 6g (0.2oz) a day
  • eat a healthy, low-fat, balanced diet, including plenty of fresh fruit and vegetables
  • be active – being physically active is one of the most important things you can do to prevent or control high blood pressure
  • cut down on alcohol
  • stop smoking. Smoking greatly increases your chances of getting heart and lung diseases
  • lose weight
  • drink less coffee, tea or other caffeine-rich drinks such as cola. Drinking more than 4 cups of coffee a day may increase your blood pressure
  • try relaxation therapies, such as yoga, meditation and stress management

The more healthy habits you adopt, the greater effect there's likely to be on lowering your blood pressure.

In fact, some people find that by sticking to a healthy lifestyle, they don't need to take any medicines at all. Find out more about preventing high blood pressure.


There's a wide range of blood-pressure-lowering medicines to choose from. You may need to take more than 1 type of medication because a combination of drugs is sometimes needed to treat high blood pressure.

In some cases, 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 might be able to stop your treatment.

Most medications used to treat high blood pressure can produce side effects but the large choice of blood pressure medicines means that these can often be resolved by changing treatments.

Let your doctor know 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

Below are the most widely used medications for treating high blood pressure. Different high blood pressure treatments work better for different ethnic groups. Your doctor will consider your ethnic background when making a treatment plan.

ACE inhibitors

Angiotensin-converting enzyme (ACE) inhibitors reduce blood pressure by relaxing your blood vessels. The most common side effect is a persistent 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 ones. Check with your doctor or pharmacist before taking anything in combination with this medication.

Calcium channel blockers

Calcium channel blockers keep calcium from entering the muscle cells of the heart and blood vessels. This widens your arteries (large blood vessels) and reduces your blood pressure.

Drinking grapefruit juice while taking some types of calcium blockers can increase your risk of side effects. You can discuss the possible risks with your doctor or pharmacist.


Sometimes known as water pills, diuretics work by flushing excess water and salt from the body through urine.


Beta-blockers work by making your heart beat more slowly and with less force, thereby reducing blood pressure.

Beta-blockers used to be a popular treatment for high blood pressure but now they only tend to be used when other treatments haven't worked. This is because beta-blockers are considered to be less effective than the other medications used to treat high blood pressure.

Find out more information about beta-blockers.

Beta-blockers can also interact with other medications, causing possible side effects. Check with your doctor or pharmacist before taking other medications in combination with beta-blockers.

Don't suddenly stop taking beta-blockers without first consulting your doctor. Stopping suddenly will lead to serious side effects, such as a rise in blood pressure or an angina attack.


Alpha-blockers are not usually recommended as a first choice for lowering high blood pressure unless other treatments haven't worked. Alpha-blockers work by relaxing your blood vessels, making it much easier for blood to flow through them.

Common side effects of alpha-blockers include:

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

Andy's story

Andy Jones liked to eat a lot of salt with his food. Whatever he ate, whether it was a Chinese takeaway or fish and chips, Andy would always add plenty of seasoning.

Although he didn’t consider himself unhealthy, Andy didn’t exercise and was overweight, which earned him the nickname Chunky.

The excessive salt Andy was adding to his food had raised his blood pressure to dangerous levels. High blood pressure caused his arteries to fur up and put extra strain on his heart.

Most people with high blood pressure don’t have any symptoms, but the condition sharply increases the risk of having a stroke.

In December 2003, Andy, who ran a courier business in Warwick, collapsed on someone’s doorstep during a delivery.

“I had a feeling like vertigo and I felt dizzy,” he says. “I knocked on the door and I told the person who answered that I was feeling unwell. I collapsed moments later.”

He had lost the use of his right side and his speech was slurred. Hospital tests confirmed he had had a stroke caused by a blood clot.

Cholesterol control

Andy was in hospital for a week, where he was given physiotherapy and speech therapy. He took medication to control his blood pressure and cholesterol.

“I was home for Christmas Eve,” he says. “I was walking again by then, but it took me 3 months to regain the use of my hand and arm.

“My speech and my ability to swallow came back within 24 hours. However, even now I struggle with tying shoelaces and using keys.”

He says his family were crucial in his recovery. “They helped with my determination to get better,” he says. “My mother walked with me every day.”

Having a stroke at 40 was a big shock for Andy. “I thought strokes didn’t happen to people my age,” he says.

In fact, out of the 150,000 people who have a stroke in the UK each year, 31,000 are under 60.

“It took me a long time to come to terms with my stroke,” Andy says. “I still suffer bouts of anxiety and depression.”

Returning to work

Andy says the stroke has left few traces, but its less obvious effects include moments of extreme tiredness.

“It’s a hidden disability that’s hard to explain,” he says. “It’s a fatigue I’ve never experienced before and it’s quite debilitating.”

He lost his business soon after the stroke, but was keen to get back to work as soon as possible, to rebuild his self-esteem. After working as a driver in the voluntary sector, Andy now works part-time in a betting shop.

Cutting out salt

He's now a lot more careful about what he eats, has cut down on takeaways and greatly reduced the amount of salt in his diet.

“I don’t add salt to my food,” he says. “If I feel like a snack, I’ll have fruit.”

He says he eats his meals more slowly, which leaves him more satisfied. “I always aim to be the last to finish,” he says. “It means I eat less but feel fuller.”

Andy believes his excessive consumption of salt helped lead to his stroke. “My diet and lack of exercise contributed greatly to my stroke,” he says.

“I wish I had known I had high blood pressure. I would have done something about it and would probably have prevented the stroke.”

Some good has come out of Andy's experience: he may have saved his younger brother from a stroke.

“After my stroke, he went to have his blood pressure checked and found it was too high. Now he’s addressing that.”

Complications of high blood pressure

High blood pressure (hypertension) puts extra strain on your heart and blood vessels.

If untreated, over time this extra pressure can increase your risk of a heart attack, stroke and kidney disease.

Cardiovascular disease

High blood pressure can cause many different diseases of the heart and blood vessels (cardiovascular diseases), including:

  • stroke – occurs when the blood supply to part of the brain is cut off
  • heart attack – happens when the supply of blood to the heart is suddenly blocked
  • embolism – occurs when a blood clot or air bubble blocks the flow of blood in a vessel
  • aneurysm – occurs when a blood vessel wall bursts causing internal bleeding

Kidney disease

High blood pressure can also 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 in your urine
  • urinating more often, particularly at night
  • itchy skin

Kidney disease can be treated using a combination of medication and food supplements.

More serious cases may require dialysis (a treatment where waste products are artificially removed from the body) or a kidney transplant.

Find out about how to prevent high blood pressure.

Preventing high blood pressure

Having high blood pressure can be prevented by eating healthily, maintaining a healthy weight, taking regular exercise, drinking alcohol in moderation and not smoking.


Cut down on the amount of salt in your food and eat plenty of fruit and vegetables.

Salt raises your blood pressure. The more salt you eat, the higher your blood pressure. Aim to eat less than less than 6g (0.2oz) of salt a day, which is about a teaspoonful.

Eating a low-fat diet that includes lots of fibre (for example, wholegrain rice, bread and pasta) and plenty of fruit and vegetables has been proven to help lower blood pressure. Fruit and vegetables are full of vitamins, minerals and fibre that keep your body in good condition. Aim to eat 5 80g portions of fruit and vegetables every day.


Regularly drinking alcohol above what the NHS recommends will raise your blood pressure over time. Staying within the recommended levels is the best way to reduce your risk of developing high blood pressure.

It's recommended:

  • Men should not regularly drink more than 3 to 4 units a day.
  • Women should not regularly drink more than 2 to 3 units a day.

Alcohol is also high in calories, which will make you gain weight. This will also increase your blood pressure.


Drinking more than 4 cups of coffee a day may increase your blood pressure. If you're a big fan of coffee, tea or other caffeine-rich drinks (such as cola and some energy drinks), consider cutting down. It's fine to drink tea and coffee as part of a balanced diet but it's important that these drinks are not your only source of fluid.


Being overweight forces your heart to work harder to pump blood around your body, which can raise your blood pressure. If you do need to shed some weight, it's worth remembering that just losing a few pounds will make a big difference to your blood pressure and overall health.


Being active and exercising regularly lowers blood pressure by keeping your heart and blood vessels in good condition. Regular exercise can also help you lose weight, which will also help lower your blood pressure.

Adults should do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity (i.e. cycling or fast walking) every week. For it to count, the activity should make you feel warm and slightly out of breath. Someone who's overweight may only have to walk up a slope to get this feeling. Physical activity can include anything from sport to walking and gardening.

Relaxation therapies

Relaxation therapy and exercise can reduce blood pressure. These therapies include:

  • stress management, meditation or yoga
  • cognitive behaviour therapy (CBT), which focuses on how thoughts and beliefs can affect the way you feel and how you cope with problems. CBT is increasingly available so check with your doctor about accessing this type of therapy
  • biofeedback, where a small monitor constantly shows you your heartbeat or blood pressure, and is used to help you try to control your blood pressure. Referrals for biofeedback can be made through a doctor


Smoking doesn't directly cause high blood pressure but it puts you at much higher risk of a heart attack and a stroke. Smoking – like high blood pressure – will cause your arteries to narrow. If you smoke and have high blood pressure, your arteries will narrow much more quickly and your risk of a heart or lung disease in the future is dramatically increased.

Content supplied byNHS
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