22nd January, 20197 min read

High blood pressure: Causes, symptoms and prevention

Last reviewed: 22/01/2019
Medically reviewed

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It’s easy to be complacent about your health, especially if the effects on your body aren’t immediately obvious.

High blood pressure (hypertension) can be caused by an unhealthy lifestyle, but there are rarely any noticeable symptoms.

According to Blood Pressure UK, only one third of people with high blood pressure are aware they have it, even though it affects around one billion people worldwide.

It can put extra strain on your heart and arteries, leading to potentially life threatening conditions like heart attack and stroke.

Low blood pressure, or hypotension, can also damage your body, although it is less common and typically caused by an underlying health condition or a medication you are taking.

In this article, you can learn about blood pressure testing, how to prevent high blood pressure and how it can be treated.

Blood pressure testing

Getting your blood pressure tested by a professional

UK guidelines suggest that all adults over 40 should have their blood pressure checked every five years.

You can request to have your blood pressure tested:

  • By your doctor
  • By a pharmacist
  • In some workplaces

There are a few steps you can take before your test to prevent any spikes in your blood pressure. For example, try to avoid eating, having caffeine, smoking or exercising an hour before the test.

You should also sit upright with your legs uncrossed for about five minutes beforehand, so you are relaxed.

An automatic blood pressure device will probably be used. You will have to roll up one of your sleeves and rest your arm so it is level with your heart. To make this easier, wear short or loose sleeves. The device’s cuff can then be strapped around your upper arm.

The cuff will tighten for a few seconds before it is released. This can feel uncomfortable, but it won’t last long. The results of the test will then be displayed on the device.

If your blood pressure is high, you may have to check a few more times at home, or wear a 24-hour monitor. This is because blood pressure can change throughout the day and you may need more than one test to confirm your results.

Those who are diagnosed with high blood pressure should start checking their blood pressure more frequently.

Testing your blood pressure at home

Automatic blood pressure monitor

Investing in your own blood pressure monitor can be a good idea if you need to test your blood pressure frequently.

Before buying one, it is important that you check it has been clinically approved.

You can find a list of validated blood pressure monitors on the British Hypertension Society (BHS) website.

Blood pressure is measured in millimetres of mercury (mmHg). When you test your blood pressure using one of these monitors, you will see two figures:

  • Systolic pressure (the pressure measured when your heart pumps blood out)
  • Diastolic pressure (the pressure measured when your heart rests in between beats)

Systolic pressure is the higher number of your blood pressure reading, and diastolic pressure is the lower number.

As a general guide:

  • Ideal blood pressure measures between 90/60 mmHg and 120/80 mmHg
  • High blood pressure measures 140/90 mmHg or higher
  • Low blood pressure measures 90/60 mmHg or lower

If you have taken your blood pressure at home and it is high or low then you should see your doctor.

High blood pressure symptoms

Most people with high blood pressure do not have any symptoms. A test is usually required to confirm high blood pressure.

However, in some cases where someone’s blood pressure is very high, they may experience:

  • A headache
  • Blurred or double vision
  • Nosebleeds

See a doctor immediately if you have any of these symptoms.

High blood pressure causes

High blood pressure is generally a reading of 140/90 mmHg or higher.

The main factors that increase your risk of high blood pressure include:

  • Age (the risk increases as you get older)
  • Being of African or Caribbean origin
  • A lack of exercise
  • Being obese
  • Regularly drinking too much alcohol
  • Smoking
  • Regular sleep deprivation
  • Regularly eating a lot of salt (more than 6g a day)
  • A family history of high blood pressure

If you are at a higher risk, you should get your blood pressure checked more frequently. Living a healthy lifestyle can help you prevent high blood pressure.

Less commonly, high blood pressure can be caused by an underlying condition, medication, or recreational drug.

Some conditions that can cause high blood pressure are:

Medications that can cause high blood pressure include:

  • Steroid medication
  • The oral contraceptive pill
  • Hormone replacement therapy
  • Certain herbal remedies (especially those containing liquorice)
  • Some recreational drugs (e.g. cocaine and amphetamines)
  • Some chemotherapy and immunosuppressants (e.g. Tacrolimus and cyclosporin)

If your doctor confirms your high blood pressure is caused by a medication or condition, they will likely change your therapy or treat the condition.

Preventing high blood pressure

High blood pressure: Causes, symptoms and prevention

The best way to prevent high blood pressure is to adopt healthy lifestyle habits, such as:

  • Eating a balanced diet
  • Lowering fat intake
  • Consuming no more than 6g of salt (a teaspoon full) a day
  • Regularly exercising (getting at least 2 hours and 30 minutes of moderate-intensity exercise - like jogging - every week)
  • Losing weight if you are overweight
  • Drinking less alcohol (no more than 14 units per week, spread out over 3 days)
  • Not smoking
  • Avoiding caffeine (which can be found in tea, coffee and energy drinks)
  • Regularly getting a good night’s sleep (at least 6 hours a night)

If you have high blood pressure despite taking these steps, see a doctor.

How to lower high blood pressure

If you have been diagnosed with high blood pressure, you should try to live as healthy a lifestyle as possible, as outlined in the section above.

Your doctor may advise you take medication, which you might have to take indefinitely.

However, If you have an ideal blood pressure for a number of years, your doctor may lower your dose or take you off it entirely. Your blood pressure will continue to be monitored regardless.

Some people experience side effects, but you talk to a doctor about changing your medication if you think it is not right for you.

If high blood pressure is caused by an underlying condition or medication, changing the therapy or treating the condition may help.


Living a healthy lifestyle can help you maintain a normal blood pressure.

This is especially important if you are at a high risk of high blood pressure. Those at a high risk should be checking their blood pressure more frequently than most.

If you ever have symptoms of high or low blood pressure, or the results of a home test are not within the ideal range, speak to your doctor.

They can check whether an underlying condition or a medication you are taking may be the cause.

To treat high blood pressure you will probably have to make some changes to your lifestyle. A doctor may also advise you take medication.

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