Hypertension: your questions answered

Measurig blood pressure

Hypertension (high blood pressure) can put a strain on your heart, blood vessels and kidneys. Dr Isla Mackenzie, a Clinical Senior Lecturer and Honorary Consultant Physician at the University of Dundee and Ninewells Hospital, explains that we should all get regular readings to avoid this silent killer.

What is blood pressure?

Blood pressure refers to the level of pressure of blood in your arteries. You need a certain amount of pressure in your arteries to keep blood moving around your body. Your heart and brain need oxygen from your blood to work.

If the vessels that supply your heart muscle or brain with blood (your arteries) get clogged up or blocked with fatty materials, less oxygen can get to them.

What is hypertension?

High blood pressure – or hypertension – means that your blood pressure is consistently higher than the recommended level.

Persistently high blood pressure can damage your arteries, put extra strain on the heart muscle and increase the risk of heart attack or stroke. High blood pressure contributes to more than a fifth of heart attacks and half of all strokes. Lowering your blood pressure reduces these risks.

We believe there are up to seven million people in the UK who have undiagnosed high blood pressure

We believe there are up to seven million people in the UK who have undiagnosed high blood pressure. The vast majority have no symptoms, which is why you may hear it called a ‘silent killer’.

What do the numbers mean?

Today, we usually measure blood pressure using an electronic blood pressure monitor. This presents the readings as two numbers: 120/80mmHg, for example. The top number is the pressure when your heart pumps, and the lower number is the pressure when your heart relaxes between each heartbeat.

How high is high?

Your blood pressure varies throughout the day, and a single reading is not representative of how your blood pressure is. High blood pressure (hypertension) is when your readings are consistently equal to or more than 140/90mmHg.

If you have your blood pressure measured and it is high, your GP or nurse is likely to recheck it several times and may suggest you have 24-hour ambulatory monitoring or home blood pressure monitoring. Severe hypertension is when your systolic blood pressure (the top number) is consistently at or above 180mmHg and/or the diastolic (bottom number) is consistently at or above 110mmHg.

Fast facts

  • The blood pressure measurement mmHg stands for millimetres of mercury.
  • Until recently, blood pressure was measured using a sphygmomanometer with a column of mercury inside it.

Who is most at risk of hypertension?

The cause of most high blood pressure is unknown (‘essential’ or ‘primary’ hypertension), but we know that lifestyle can affect blood pressure. Most people I see with high blood pressure have something in their lifestyle they can improve on. You can help to lower your blood pressure if you:

In a very small number of people, there is a specific cause for their high blood pressure (known as ‘secondary hypertension’). For example, some people are taking a medication or have a hormonal problem that causes high blood pressure.

Certain ethnic groups are more prone to developing high blood pressure – for example, those from African-Caribbean communities. We think they are more sensitive to salt. African-Caribbean people also appear to be more at risk of severe hypertension than other ethnic groups.

Is my family history a factor?

Several genes are involved in regulating blood pressure, and although high blood pressure can appear to run in families, it is not as clear cut as that. Extremely rarely, high blood pressure is caused by a specific gene mutation in a family.

How often should we have our blood pressure checked?

Current guidelines recommend everyone has a blood pressure check at least once every five years. If you have high blood pressure, or it is close to 140/90mmHg, you should have it checked more regularly. Your GP or nurse will be able to tell you how often.

What if I want to monitor my own blood pressure at home?

Current guidelines recommend everyone has a blood pressure check at least once every five years

Blood pressure monitors are widely available to buy. You can read more about choosing a blood pressure monitor and watch our video of how to measure your blood pressure at home. If you're measuring your own blood pressure, it's best to do it at the same time each day, ideally morning and evening.

Will I need to take medication?

Making healthy lifestyle choices can help, but many people still need medicines to lower their blood pressure. There are several types, known as ‘antihypertensives’. Most either dilate (relax) your blood vessels or change how your body handles salt.

Many people need more than one type of medicine to treat their high blood pressure. The most common ones are ACE (angiotensin-converting enzyme) inhibitors, angiotensin-II receptor blockers (ARBs), calcium channel blockers and thiazide (and thiazide-like) diuretics.

Are there side effects?

Most people won’t experience any, but there’s a chance you will feel a little light-headed for a day or two after you first start taking them. This should pass, although if you experience any other side effects or are worried, talk to your GP. If one type of medicine does not suit you, your GP will be able to recommend another type. There are several different options for treatment.

Is low blood pressure a problem, too?

Low blood pressure is a reading of less than 90/60 mmHg. Most people with low blood pressure won’t have any symptoms, but it can cause dizziness and fainting. Your GP will probably suggest further tests to rule out an underlying cause (some neurological conditions and hormonal problems can cause low blood pressure). Many people have naturally low blood pressure and are perfectly healthy.

Dr Isla Mackenzie

Dr Isla MackenzieDr Mackenzie is a Clinical Senior Lecturer and Honorary Consultant Physician at the University of Dundee and Ninewells Hospital, Dundee. She is a Fellow of the British Hypertension Society with special interests in hypertension, cardiovascular disease and safety of medicines. She is involved in the PATHWAY 1, 2 and 3 studies and the Treatment In Morning versus Evening (TIME) study – all funded by the BHF.

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