High blood pressure - causes and symptoms

Blood pressure explained

What is blood pressure?

Blood pressure is the pressure of blood in your arteries. Your arteries are the vessels (tubes) that carry blood from your heart to your brain and the rest of your body. You need a certain amount of pressure to get the blood moving around your body.

Blood pressure is measured using 2 numbers:

• Systolic pressure: this is the higher of the 2 numbers. It’s the pressure against your arteries when your heart is pumping blood around your body.
• Diastolic pressure: this is the lower of the 2 numbers. It shows how much pressure is in your arteries when your heart relaxes between beats.

Your blood pressure naturally goes up and down throughout the day and night, and it’s normal for it to go up while you’re moving about.

Learn what normal blood pressure readings look like. 

What is high blood pressure?

High blood pressure is when your overall blood pressure is always high, even when you are resting. 

High blood pressure is a serious condition. If you do not get treatment, high blood pressure can cause complications like loss of vision and sexual dysfunction.

Your arteries are normally stretchy, so they can cope with your blood pressure going up and down. But with high blood pressure, your arteries lose their stretchiness, becoming stiff or narrow.

This narrowing makes it easier for fatty material (atheroma) to build up. This narrowing and damage to the arteries lining your heart or brain could trigger a life-threatening heart attack or stroke.

If left untreated, high blood pressure can also lead to conditions such as:

• kidney failure
• heart failure
• vascular dementia.

Causes

What causes high blood pressure?

In most cases, there is not a specific reason for the cause of high blood pressure, but there are things that can increase your risk. These include:

• getting older
• having a family history of high blood pressure
• smoking
• drinking too much alcohol
• eating too much salt and not enough fruit and vegetables
• not getting enough exercise
• being overweight, especially around your mid-section
• ethnicity, people who are of Black African or Black Caribbean descent are at a higher risk of having high blood pressure.

For some people, a cause of high blood pressure is found. This is known as ‘secondary hypertension’.

Examples of secondary hypertension include:

• kidney disease
• diabetes
• a condition called obstructive sleep apnoea, which can lead to disturbed sleep
• some medicines, such as oral contraceptives
• some over-the-counter and herbal medicines.

If you are worried that any medicine or remedy might affect your blood pressure, ask your doctor or pharmacist about it.

• Read more information about secondary hypertension.

Can pregnancy lead to high blood pressure?

Around 1 in 10 women develop high blood pressure during pregnancy. It is often caused by a condition known as pre-eclampsia. This increases the risk of long-term high blood pressure.

Research funded by the BHF found that lowering the blood pressure of birth mothers within 6 weeks of giving birth reduced their long-term risk.

Symptoms

What are the symptoms of high blood pressure?

Most people do not know they have high blood pressure because there are no obvious symptoms. That's why it's so important to get your blood pressure checked regularly.

Rarely, it can cause symptoms like blurred vision, headaches and nosebleeds.

Blood pressure readings

What's a healthy blood pressure reading?

There are 2 categories of normal blood pressure:

• Normal blood pressure is usually considered to be between 90/60 mmHg and 130/85 mmHg. For people over 80 years old, because it’s normal for arteries to get stiffer as we get older, the ideal blood pressure is under 150/90 mmHg (or 145/85 mmHg at home).
• High-normal or slightly raised blood pressure, sometimes called ‘pre-hypertension’, is when your blood pressure is high but it is not yet diagnosed as hypertension. It’s usually considered to be above 130/85 mmHg to 139/89 mmHg.

What's a high blood pressure reading?

There are 3 different stages of high blood pressure:

• Stage 1: this is when your blood pressure is between 140/90 mmHg and 159/99 mmHg in the clinic, or 135/85 mmHg to 150/95 mmHg at home.
• Stage 2: this is when your blood pressure is between 160/100 mmHg and 180/120 mmHg in the clinic, or over 150/95 mmHg at home.
• Stage 3: this is when your systolic blood pressure is over 180 mmHg or your diastolic blood pressure is over 120 mmHg in the clinic. This may also be called ‘severe hypertension’, and your GP will need to assess you urgently for further investigations.

Discuss your readings with your healthcare team and ask any questions you have. Together, you might want to set a target blood pressure that’s right for you and your health goals.

These are just guidance ranges. Speak to your doctor about what blood pressure range to aim for.

Where can I get my blood pressure checked? 

As many as 5 million adults in the UK have undiagnosed high blood pressure and do not know they are at risk. The only way to know whether you have high blood pressure is to have it measured. You can measure your blood pressure at home.

• Learn how to measure your blood pressure at home.

You can also get your blood pressure checked at:

• GP surgeries
• some pharmacies
• some workplaces.

If you’re a healthy adult aged 40 to 74, and live in England, you’re likely to be invited to a free NHS Health Check every 5 years, which will include a blood pressure check.

You can also check your blood pressure at home. In England, a scheme called Blood Pressure @home is in place to support people with this, which you can ask your GP about. There is also a similar scheme in Scotland called the Scale-Up BP initiative. Ask your doctor about similar arrangements in other parts of the UK.

How often should I check my blood pressure?

If you’re a healthy adult aged 40 to 74, it’s a good idea to get your blood pressure checked every 5 years. You may be invited for an NHS Health Check in England once you turn 40. There may be other services available in Scotland and Wales. Ask your GP about how you can get your blood pressure checked.

If you have been diagnosed with high blood pressure and it's under control, you’ll normally be monitored yearly, along with reviewing any medicines you take. When you start new medicines or have dose changes to existing ones, your blood pressure will need to be checked more than once a year.

Check with your healthcare team how often to measure your blood pressure at home if you have your own monitor. Try keeping a diary of your readings. This will help your healthcare team spot patterns, and it might be motivating to see how your blood pressure improves over time.

Diagnosis

How is high blood pressure diagnosed?

Your blood pressure will usually need to be checked more than once to confirm a diagnosis of high blood pressure.

This is because blood pressure can go up and down a lot during the day. When people have their blood pressure checked in the clinic it can be higher than expected, especially if they feel nervous or anxious.

If your blood pressure is high in the clinic, you might be told to monitor it at home for a few days so they can calculate an average to see if you have high blood pressure. If it is dangerously high, you should seek urgent medical help.

You may also be given a 24-hr monitor to wear to check your BP. This is called ambulatory blood pressure monitoring, or ABPM.

By looking at all your blood pressure readings over a few days, your GP can work out what your 'average’ blood pressure is. 

• Try our free blood pressure diary to help keep track of your readings.

In some cases, your GP might want to run other tests as well. For instance, they might want to do blood tests to check your cholesterol levels and kidney function or check your heart rhythm with a test called an electrocardiogram (ECG).

Managing high blood pressure

How do I lower my blood pressure?

There are lots of things you can do to help lower your blood pressure, such as:

• Eat a healthy balanced diet that includes a variety of foods like fruits, vegetables, whole grains and oily fish. Limit salt and ultraprocessed foods like cakes, sweets, crisps and fried foods.
• Try to be more active. For example, you could commit to walking every day at lunchtime, try a new hobby or swap a short drive for a walk or cycle.  
• Reduce the amount of alcohol you drink each week. For example, you could swap one drink for a non-alcoholic version or swap a pint for a half pint of beer.  
• Stop smoking. You can get support from your local pharmacy or GP to reduce and eventually stop smoking.
• Medicines. Your GP might recommend medicines that can help you lower your blood pressure. These usually include beta blockers, diuretics, ACE inhibitors, angiotensin receptor blockers and calcium channel blockers.

Your GP can help you create a plan to reduce your blood pressure. By making lifestyle changes, you can lower your blood pressure and keep it at a healthy level.

This useful tool developed by the NHS helps you make a plan that you can discuss with your GP.

Your GP may also offer you medicine to lower your blood pressure if it’s high or very high.

• Read Joyce’s story to learn how she managed to lower her blood pressure with help from her GP.

Get support

• Speak to our cardiac nurses by phone, callback, email or online chat on Heart Helpline (Monday to Friday, 9am to 5pm).
• Sign up to our Heart Matters magazine for online tips, support and recipes to look after your heart health.
• Join our online HealthUnlocked community to speak to other people going through the same experience.

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