What is high blood pressure?

Lesley Dobson / 20 March 2017

Find out what high blood pressure is, what causes it and what you can do to lower your blood pressure.

Your blood pressure is measured using two figures. These show your blood pressure when your heart is pumping your blood around your blood vessels, and your blood pressure when your heart is between heart beats.

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Blood pressure guide

Our blood pressure changes often, depending on what we are doing. It is higher if you are doing something strenuous, like walking up a hill, and lower if you are sitting down and relaxing.

If your blood pressure is 140 over 90mmHg, or more, over the space of a few weeks, you’ll be seen as having high blood pressure. The readings your doctor would like to see when they take your blood pressure are between 90/60mm/Hg and 120/80mm/Hg. This is regarded as being the ideal range for blood pressure.

Diastolic vs systolic blood pressure – what do the two numbers mean?

‘High blood pressure is when your blood pressure is persistently above 140/90. Your blood pressure can fluctuate over the course of a day, and a week,’ says Julie Ward, senior cardiac nurse at the British Heart Foundation. ‘It’s when your blood pressure is persistently high that it’s a problem.’

 ‘We advise patients to keep a diary of their blood pressure readings, because our blood pressure does fluctuate over the course of 24 hours, and over a week, so it’s much better to get an average.’

 ‘If you have a history of high blood pressure in your family, or there are other reasons why you might be at risk, it’s a good idea to buy a blood pressure machine, and keep a diary of your results. A one-off reading doesn’t tell you as much as a series of readings taken over a week or so.’

 ‘High blood pressure is when the pressure of blood in your arteries is persistently at a high level, and so damages the lining of the arteries. And it makes you more predisposed to the furring up of the arteries, which is atherosclerosis, which can lead to coronary heart disease. It can also make you more at risk of heart attack and stroke.

 ‘So, it’s the persistently high pressure of your blood going through the arteries – and some of the veins as well – that damages the wall of the vessels, and then makes you predisposed to heart attacks and strokes.’

How many people have high blood pressure?

About 16 million people in the UK have high blood pressure. And because high blood pressure hardly ever causes any symptoms, many people don’t realise that they have this condition. In fact, out of the 16 million people in the UK with this condition, about seven million aren’t aware that they have high blood pressure, because there are no signs to warn them.

How is blood pressure measured?

Blood pressure is usually measured by a doctor or nurse, using something called a sphygmomanometer. First, you’ll have a fabric cuff wrapped around your upper arm. The control box, that displays your blood pressure readings, will pump air into the cuff that will expand until it feels quite tight around your arm.

Your blood pressure reading will be displayed on a digital display attached to the cuff. Your doctor or nurse may take a couple of readings to check them, especially if they are higher or lower than ideal readings of are between 90/60mm/Hg and 120/80mm/HG.

You may also come across older blood pressure monitors that work in a similar way, but aren’t electronic, and involve the doctor using a stethoscope to listen to your pulse instead of the equipment doing this automatically.

How to monitor your blood pressure

Who gets hypertension, or high blood pressure?

Hypertension – the medical term for high blood pressure – can affect different people for different reasons.

One of the main causes is age. As you grow older, your chances of developing high blood pressure increase.

Other risk factors include your ancestry. People with families who have South Asian or African-Caribbean origins are genetically more likely to develop high blood pressure. This also applies to people who have family members who have had high blood pressure.

If you haven’t taken the best care of yourself, you are likely to be at greater risk of having high blood pressure. There are a number of unhealthy habits that are known to increase your likelihood of having high blood pressure.

10 lifestyle changes to help lower blood pressure

Diet and high blood pressure

These unhealthy habits include having a high risk diet – consuming too much salt, too much alcohol and/or coffee, and not eating enough fruit and vegetables. This may lead to you being overweight, which can also increase your risk of high blood pressure. And not doing enough exercise also pushes your risk up.

10 foods that may help lower blood pressure

Stress and high blood pressure

Having a lot of stress in your life can also increase your risk of having high blood pressure. This may be harder to change than reducing salt in your diet, and doing more exercise. If stress is really affecting your life, it’s worth making a list of all the problem areas, and looking at ways of reducing your stress. You could also talk to your GP and see if you could be referred for Cognitive Behavioural Therapy (CBT).

How stress affects your body and mind

What are the signs and symptoms of high blood pressure?

One of the reasons why we need to have our blood pressure checked regularly is that high blood pressure doesn’t usually cause any symptoms or signs. This is the only way that you can find out whether you have high blood pressure. Having said that, having a high blood pressure reading one day doesn’t mean that you’ll have an equally high blood pressure reading the following week or month.

If your GP finds that you have high blood pressure having checked you on one occasion, they won’t automatically decide that your blood pressure is high all the time. They are likely to ask you to come in for at least one or two more blood pressure checks.

There is one symptom that is sometimes mentioned by people who are found to have very high blood pressure, and that is headache. However, that doesn’t mean that everyone who suffers with headaches has high blood pressure.

12 types of headache and what they mean

If you wear glasses and have your eye-sight checked, it’s possible that your ophthalmologist may be able to see damage that high blood pressure has caused to your optic nerve. If this happens you should have your blood pressure checked by your GP as soon as possible.

Is it time for an eye test?

One of the serious health issues connected to high blood pressure is stroke. If you suddenly feel dizzy, and have trouble keeping your balance, seek medical help straight away, as these signs could mean that you are having a stroke.

Stroke: signs, symptoms and risk factors

Saga Health Insurance offers a range of health plans which provide cover if you develop high blood pressure (hypertension). If you've already been diagnosed they can often still cover your hypertension anyway, subject to some simple health questions and an additional premium. Find out more.

What causes high blood pressure – essential hypertension

Also known as primary or idiopathic hypertension, this means that your GP is referring to high blood pressure that can’t be pinned down to a particular cause. This is generally regarded as being 140/90mmHG or higher, when your blood pressure is taken in your GP’s surgery.

This level of high blood pressure may generally be regarded as the point at which giving medication to lower blood pressure, makes a clear difference to the patient’s health. In other words, when someone has this blood pressure reading, giving him or her treatment to reduce it will make a difference to their health.

5 new blood pressure treatments

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What causes high blood pressure – secondary hypertension

Secondary hypertension is blood pressure that has been caused by another health problem.

Kidney disease is the leading trigger for secondary hypertension.

Endocrine diseases come next in terms of causing secondary blood pressure.

Endocrine diseases include:

  • Cushing’s syndrome
  • Cohn’s Syndrome
  • thyroid disfunction
  • hyperthyroidism

Other possible causes include:

  • obstructive sleep apnoea
  • some medications
  • alcohol
  • some antidepressants
  • some herbal remedies

How to deal with sleep apnoea

If you are concerned that any medicines or herbal remedies you take could increase your risk of high blood pressure, talk to your pharmacist or GP.

If you haven’t had your blood pressure taken recently, ask your pharmacist or GP about having it checked.


The opinions expressed are those of the author and are not held by Saga unless specifically stated.

The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.