Written by Dr Katie Stephens, GP
Dr Katie graduated from the University of Manchester in 2007 (MBChB) and completed her GP training in the West Midlands in 2012 (MRCGP).
This is quite literally a measure of the amount of pressure that your blood exerts against the walls of the arteries (blood vessels carrying blood away from the heart) it travels through, i.e., the pressure coming from the blood.
A blood pressure reading has two components to it:
This is the higher or ‘top’ number of the two.
It represents the pressure when the left ventricle contracts.
The left ventricle is the main pumping muscle that pushes blood out of the heart and around the body.
This is the lower, ‘bottom’ number, which represents the pressure in your arteries while your heart is filling with blood between beats.
(As the heart is resting and not pushing blood out, it makes sense that the pressure then will be lower.)
Both figures are significant and should be monitored to ensure that they remain within a healthy range.
At the time of writing this guide, raised blood pressure is significantly underdiagnosed and undermanaged in the UK, compared to other countries: only 35% of people in England with hypertension (the medical term for high blood pressure) have their blood pressure under control, compared to 65% in Canada.
And only half of England’s adults know what their blood pressure is, so it isn’t surprising that around 5.5 million people in England alone have hypertension but don’t know about it.
At the same time, high blood pressure is a major cause of serious health issues like heart attacks and dementia, and is even thought to be the number one cause of strokes. It is also very easy and inexpensive to check.
When hypertension is diagnosed, there are effective treatment options, including making simple lifestyle changes.
This is why it is of utmost importance to monitor your blood pressure and ‘Know Your Numbers’.
This depends on where you are taking the readings (we expect them to be a little lower when you are at home and likely to be more relaxed), and if you have any other medical conditions, such as diabetes or kidney disease, that might affect your own individual BP target.
For most people checking their blood pressure at home who don’t have other relevant medical conditions, we would consider an upper limit of ‘normal’ to be a systolic pressure of less than 135 mmHg and a diastolic of less than 85 mmHg*.
Of course, ideally, we wouldn’t want people to sit right at the edge of this cut off if possible.
So, while a blood pressure of 134/84 mmHg is officially acceptable, it would warrant much closer monitoring than something like the textbook 120/80 mmHg, which is more ideal.
Of course, it is also important that blood pressure is not too low, as this can also cause problems such as light-headedness and falls.
*The proper measurement unit of blood pressure is ‘mmHg’. This stands for ‘millimetres of mercury’ as mercury was used in the original blood pressure machines and it’s movement was measured against a ruler-type gauge.
Hypertension is a medical diagnosis given when the blood pressure is persistently found to be raised.
It can lead to damage both to the heart and to other organs in the body, as this article will explore.
Low blood pressure (hypotension) can have several causes, but if it isn’t normal for you, you are likely to feel somewhat lightheaded or dizzy as not enough blood reaches important organs, such as the brain, in time.
Typically, a reading of less than 90/60 mmHg would be considered low. (See Symptoms of Low Blood Pressure for more information.)
Enter your readings here to find out where your blood pressure is compared to where it should be.
Once you’ve entered your results, you’ll be placed on this chart. Provided you don’t have other relevant medical conditions, you should be aiming to get your blood pressure within the green zone.
The hose-pipe analogy when talking about blood pressure has served me well thus far so forgive me for referring to it again now: If you think about the water coming through the hose as your blood, the hose itself represents your artery, and the tap represents your heart.
While not everything that increases blood pressure can be represented by one of these facets misbehaving, there are a number that can:
Turning the tap up higher represents the heart squeezing harder with each pump.
This happens if there is some sort of stimulant acting on the heart, such as caffeine or stress.
For more information on how stress can cause high blood pressure, please read my article here.
Narrowing the diameter of the hose means the water comes out under more pressure.
Hence why popping your thumb on the end of the hose causes the water to squirt out faster and further.
This is more or less what happens with the disease process called atherosclerosis.
Atherosclerosis is the name given to fatty plaques building up on the inner aspects of arteries.
These plaques, in turn, can have multiple causes, such as raised levels of bad cholesterol and smoking.
Raised levels of salt in the blood stream have a local effect in the body of pulling in fluids from surrounding areas through osmosis.
(The hose analogy does fail me somewhat here, unless our hose develops a permeable membrane and is in a pond!).
Regardless, this leads to extra water coming through which increases the pressure.
Other important causes which should certainly be mentioned are: obesity, kidney damage, excess alcohol and of course, what you inherit in your genetic makeup.
People groups at increased risk of developing hypertension include those over the age of 65y and those of Black ethnicity.
There are still other causes – for an even more extensive list, please refer to this page.
Typically, when someone is diagnosed with hypertension, it is one of two types:
This makes up the vast majority of cases of hypertension.
By labelling it as ‘Primary’, what we are saying is that it isn’t caused by a second, underlying disease. Instead, it is likely caused by one of the many lifestyle or hereditary factors listed above, such as diet, obesity, and genetics.
Only a small minority of cases are labelled as Secondary Hypertension.
They tend to be due to a significant underlying medical condition. Examples of these are problems with the adrenal gland, such as a tumour (e.g., phaeochromocytoma), other hormonal imbalances (e.g., Cushing’s syndrome), Kidney Disease, Obstructive Sleep Apnoea, and medication (e.g., steroids, anti-inflammatory medication, the Pill).
Most people with high blood pressure don’t have symptoms.
They may find out they have hypertension when they have their blood pressure checked at their healthcare practitioner’s office for another reason, or if the hypertension causes a major problem, such as a stroke.
Therefore it is so important to check your blood pressure proactively rather than rely on being prompted by the appearance of a new symptom, or worse, a major health event like a stroke or heart attack.
However, in some instances, when the blood pressure suddenly shoots up to an emergency level (generally >180/120 mmHg), it may lead to headaches or visual changes.
It causes ongoing damage even when it isn’t this high though, so it’s best to have it checked periodically.
Some people have a naturally low blood pressure.
This might be the case if you are particularly sporty or active or have a slim build.
Usually this doesn’t cause a problem most of the time in these cases.
However, if your blood pressure drops lower than normal for you, you may experience one of the following symptoms:
- feeling light-headed, dizzy or faint
- blurred vision
There are serious medical conditions that can lead to a blood pressure dropping also, such as dehydration, sepsis and other types of shock, and endocrine disorders, not to mention medication side effects.
Depending on the cause and the severity of your symptoms, you may need to seek urgent medical attention.
For more information, pop your reading in our blood pressure tool here, or contact NHS 111.
You can measure your blood pressure at a variety of places – when you next visit your NHS GP Surgery, at your local chemist, at some gyms, or you can take a blood pressure measurement at home with one of our devices.
You can find our full range here.
If you decide to purchase your own machine, it’s important to check that the device is validated by the British and Irish Hypertension Society (BIHS).
We have a selection of machines are not only approved by the BIHS, but also by the European Society of Hypertension.
Generally, machines that use upper arm cuffs are more precise than the wrist monitors.
The advantage of taking your reading at home is that it tends to be a more accurate reflection of your blood pressure level than when it is checked at the doctor’s office.
In fact, the National Institute of Health and Clinical Excellence (NICE) actually recommends that readings taken from home are used when diagnosing someone with hypertension for the first time.
Their ‘gold standard’ advice is to use something called ABPM, which stands for Ambulatory Blood Pressure Monitoring.
This is when you wear a special BP machine for a full 24 hours, which inflates periodically and records your readings throughout.
But they do say that where this isn’t possible, the next best option is Home Blood Pressure Monitoring:
This is where the blood pressure is checked by the user themselves at home, using a BP machine.
It should be done systematically, morning and evening, every day for at least 4 days but ideally 7.
Each time it is done, it should be repeated after at least a minute spent sitting quietly.
The readings from the first day are discarded and the remainder used to work out an average.
Rather than carrying on constantly monitoring readings, this average reading is then used to assess if the person does indeed have hypertension, or not.
The benefit of sticking to a regime like this is that it avoids the ‘let’s put it off for another day’ attitude that can sometimes happen when people check their blood pressure at home and see that it is a bit raised.
If it’s not sky-high, people may be falsely reassured that it’s okay to leave things as they are and carry on just monitoring the situation.
This is actually quite dangerous, as a raised blood pressure that is left untreated and just monitored can still be causing serious damage and could lead to conditions like strokes, heart attacks and dementia, even if it doesn’t appear dramatically above normal levels.
Another benefit is that it means there isn’t an onus on checking a blood pressure daily, indefinitely.
For some people this daily checking can actually cause anxiety which then raises the blood pressure further, leading to a vicious cycle.
If your blood pressure is above your target (for those under 80y with no other medical conditions, your target is likely to be less than 135 mmHg on the top and less than 85 mmHg on the bottom), provided it isn’t at an immediately dangerous level like >180/120 mmHg (in which case, please attend A&E!), I would recommend making sure that your machine is an accurate one, then following the NICE steps for Home Blood Pressure Monitoring described above, and contacting your GP with the results.
Make sure you make a plan with your GP if you are at a ‘borderline’ level that doesn’t need medication yet, which includes agreeing what lifestyle changes you will make and when you will repeat your week’s HBPM and follow up with them again.
One of the most important instructions is to make sure that you sit quietly for at least a minute before taking your blood pressure.
As the heart is a dynamic organ, it will beat harder to pump blood around the body in response to the body’s demands.
Even a slow walk around the room increases the energy and oxygen consumption in the muscles of the legs, meaning they need more blood pumping to them compared to when they are at rest.
The heart responds to this by pumping harder (raised blood pressure) and faster (raised heart rate).
Sitting still has the opposite effect – the muscles of the body are at rest and so don’t need as much blood pumping to them so the heart can take the pressure off by beating less hard (lower blood pressure) and slower (lower heart rate).
If you have just been particularly active, or if you’ve smoked a cigarette or had a caffeinated drink, you may need closer to 30 minutes for your heart to ease off to a ‘resting’ level. Once you are ready, open the instructions that came with your machine.
These will vary somewhat depending on whether you are using an upper arm cuff or wrist machine.
However, apart from being mindful of sitting quietly for an appropriate length of time before, the other important steps to follow for both types of machine include:
- Sitting still and quietly throughout the process. Even talking while the cuff inflates increases the body’s need for oxygen and tends to raise the blood pressure.
- The cuff of the machine should ideally be worn directly on the skin or potentially through only very thin clothing. Thick sleeves can affect the accuracy.
- Your arm should be supported at the level of your heart (roughly in line with your breastbone).
- Your back should also be supported.
- Both feet should be on the ground (legs uncrossed).
Once you have a reading, write it down and repeat the process after another minute or two of sitting quietly.
If the second reading is similar to the first, this is likely to be accurate.
If it is much lower, it is likely that the first reading is the inaccurate one. In that case, write the result down and repeat your reading a third time after another minute or two of sitting quietly.
Once you have two readings that are somewhat similar, take an average of them. Pop your average in our blood pressure tool or record it somewhere safe to refer to later if you are following the Home Blood Pressure Monitoring plan.
An important point to note here – if you have an irregular heart rhythm (an example of this is Atrial Fibrillation, or AF), this may cause inaccuracies when using home blood pressure monitors.
The most reliable way to get your blood pressure checked in these instances is with one of the manual machines where the practitioner inflates the device by squeezing the pump and listens for your pulse with a stethoscope on your arm.
All of Kinetik’s blood pressure machines come with an irregular heartbeat detection alert to warn you if this may be the case for you.
If the alert shows, it’s important that you do get this looked at somewhat urgently, as this can be a serious medical condition of its own accord.
And, as is always the case, if you also have life-threatening symptoms such as chest pain, shortness of breath, or lightheadedness, and the alert is showing, please do seek immediate medical attention at your nearest A&E department.
For someone who has been diagnosed with hypertension for the first time, there are certain tests that your GP will want to have done to establish what damage may have already been inflicted on your body, and how much risk you have of further damage.
These include the following:
- An ECG (heart tracing done by popping sticky electrodes on the chest and limbs, not painful): To check for possible heart damage, such as left ventricular hypertrophy (enlargement of the left ventricle, or main heart chamber, linked to having had to pump harder for a prolonged period. Can cause serious problems – see Enlarged Heart.)
- Blood tests: Assessing cholesterol levels (lipid profile), average sugar levels (HbA1c), how well the kidneys are filtering the blood (eGFR, creatinine).
- Urine tests: Checking for blood and raised protein levels in the urine – a sign that the kidneys have been damaged and are leaking things from the bloodstream to the urine.
- Eye exam: Raised blood pressure can cause damage at the back of the eye which can then affect vision. This is something that can be checked in detail by an optician.
- Other tests: If the GP is suspecting that this is one of those rare cases of Secondary Hypertension, they may arrange for a variety of other tests, depending on the underlying suspicion. This may be imaging, a 24-hour urine collection, or other blood tests.
The reason for checking the kidneys with both urine and blood tests is due to how the kidneys and heart normally work very closely together.
The kidneys filter the blood stream to make urine.
If there is damage to the kidneys and they aren’t able to filter the blood fast enough, the heart responds by pumping harder to push the blood through them faster, resulting in a rise in your blood pressure.
However, if your blood pressure stays high, this in itself can also damage the kidneys.
So, kidney damage can both cause raised blood pressure, and be a result of raised blood pressure.
Establishing your baseline level of current damage from hypertension, and risk of further damage (e.g., if your sugar levels or bad cholesterol levels are raised), can both help form a picture of how aggressive you may need to be in getting your raised blood pressure under control.
For those interested, you can work out your individual risk score by popping your demographics and blood results into the calculator that GPs use here.
The GP will then evaluate this data in the context of any other medical conditions you have, and what severity of hypertension you have, in order to suggest the best course of treatment.
The severity of hypertension is split into stages in the UK:
Average home readings of >135/85 mmHg or clinic readings of >140/90 mmHg, but less than Stage 2.
Typically, medical treatment would be offered in addition to lifestyle advice if the person is less than 80 years old and have any of the following: established damage in the body from hypertension, known to be at increased risk of damage, or if they have kidney disease, diabetes or cardiovascular disease.
For those 80y or older, it is important to consider potential frailty and the associated risks of causing more harm by treating (e.g., lowering the blood pressure by so much that they fall and break a hip, or risks from the medication itself).
Average home readings of >150/95 mmHg or clinic readings of >160/100 mmHg but less than Stage 3. Generally, all ages would be offered treatment in addition to lifestyle advice.
Those under 40 years old may be referred for further investigations into a possible underlying cause.
A clinic reading of 180/120 mmHg (this means either the top reading is above 180 mmHg or the bottom reading is above 120 mmHg – they don’t both need to be above this level).
Usually these patients need to be seen in A&E, especially if there are any other concerning signs or symptoms such as new confusion, chest pain, ankle swelling, shortness of breath, or visual changes.
Of course, this is something that should be agreed with your doctor, as they will have access to your individual details, and therefore have the best idea of your risk and what treatments are safe and best for you.
However, for educational purposes, I will go through some of the main treatment options below.
If you refer to the list of causes of hypertension, you won’t be surprised to see the following are included in ways to reduce a raised blood pressure:
- Reducing salt in your diet (provided you aren’t pregnant – this can be dangerous for your baby).
- Reducing any excess caffeine or alcohol (including having at least 1 – 2 days/week that are alcohol-free).
- Reducing intake of foods high in ‘bad cholesterol’ (bacon, sausages, cakes, anything fried).
- Increasing heart-healthy foods such as oats, brown carbohydrates (bread, rice, pasta), seeds, nuts, oily fish, fruit and vegetables. For more information, see this helpful leaflet from the British Dietetic Association.
- If your BMI is raised (pop your height and weight in our calculator to check it), try reducing portion sizes a little, or make other modifications to your diet that can be sustainable. I’d avoid against any fad diets or restricting to just a few ‘superfoods’. Making healthy swaps that you are happy with tends to lead to longer-lasting changes. For more information on healthy ways to lose weight, visit this article from patient.info.
- Quitting smoking. Not only does this lower your blood pressure, but it also reduces your risk of some of the serious complications of having raised blood pressure (hence it’s inclusion in the calculator tool that GP’s use). If you try out the calculator, have a go at changing your smoking status to see what difference it makes to your risk.
- Increasing exercise. If you are after one lifestyle change that can reap a whole host of benefits (apart from quitting smoking), increasing your exercise may be it: Not only can it reduce high blood pressure, it also has a direct effect on boosting the health of the heart and the blood vessels. What’s more, it can also help to improve your cholesterol, reduce stress, and can burn more calories, therefore helping reduce excess weight. Ideally, aim for 30 minutes/day of moderate to vigorous activity. If this is a big jump up from your current activity levels, please don’t be put off from starting – make small, achievable goals that you can adjust every 2 – 4 weeks. Any increase in movement towards the end goal of 30 minutes/day is a metaphorical and literal step in the right direction.
- Reducing stress. How this is achieved will probably look somewhat different for each person reading this guide. You may well already know what works best for you, but if not, here are some ideas to get you started: breathing exercises, yoga, prioritising good sleep hygiene, staying connected with others, analysing sources of stress (e.g., workload) for possible changes.
There are a variety of medications that can be used.
The one that your GP recommends will vary depending on your age, ethnicity, pregnancy status/risk, and any other health conditions you have or medication you may already be taking.
The potential side effects of the options and monitoring regimes are summarised in NICE’s patient leaflet, but here is a brief run-down of the more common options.
These are often recommended for people aged <55 years (who are not of Black ethnicity), or for those of any age and ethnicity with Type 2 Diabetes. Common examples are Ramipril and Lisinopril.
A common side effect is a dry, night-time cough.
‘Angiotensin II-Receptor Blockers’ are sometimes used when an ACE-Inhibitor isn’t tolerated. Examples include Irbesartan and Losartan.
These tend to be first line for those over 55y, or for people of Black ethnicity (provided they don’t have Type 2 Diabetes).
Commonly used examples include amlodipine and felodipine. They can lead to ankle swelling.
These are particularly useful for those people who also have heart failure – a condition that can cause fluid to accumulate.
Indapamide is the most commonly started diuretic for treating hypertension now, but there are others that are used too, such as Bendroflumethiazide.
As guessed from their mode of action, they can cause extra trips to the loo, which means they usually aren’t taken right before bed.
If the blood pressure doesn’t improve enough with one of the above medications on their own, your GP may advise adding in a second (with certain exceptions – e.g., ACE-Inhibitors and ARBs shouldn’t be used together).
Rarely, three or more medications may be used.
Why does it matter so much whether someone’s blood pressure is raised?
Well, we know that hypertension can cause major issues around the body, if it isn’t kept under control.
The opposite is also true – getting your blood pressure down to optimal levels reduces your risk of the following.
According to the WHO, hypertension is responsible for about half of all Strokes and Heart Attacks.
Both of these fall under the umbrella term of ‘cardiovascular disease’ – meaning a problem with the heart or blood vessels. Hypertension causes atherosclerosis – a build-up of fatty tissue inside an artery, which reduces the blood flow through it and can even block it off completely.
When this happens to a blood vessel in the brain, it causes a stroke.
When it happens to a blood vessel supplying the muscular walls of the heart itself (coronary artery), it causes a heart attack.
If it happens to a blood vessel further away, it is termed Peripheral Artery Disease. A classic example of the latter is Intermittent Claudication – a painful and limiting condition where calf pain occurs on walking.
Raised blood pressure can cause an increase in the size of the main pumping chamber of the heart, the left ventricle (left ventricular hypertrophy).
This happens in a third to half of people with hypertension and typically happens more in those whose blood pressure is more severely raised18.
While usually muscular size increases sound positive, this is actually very much a negative thing.
If the left ventricle grows larger, the heart becomes less efficient and coordinated in its pumping.
This in itself can cause a host of problems, including Heart Failure.
This is when the heart pumps less efficiently, leading to something of a traffic jam of blood not getting through.
This can cause pooling of fluid in the legs, causing mobility issues, and in the lungs, leading to breathing difficulties.
Also known as arrhythmias.
This basically describes when there is an interruption to the normal ‘lub dub… lub dub’ pattern of your heart beating.
There are a variety of abnormal rhythms that can happen as a result of hypertension.
One of the more well-known ones is Atrial Fibrillation, or AF.
This is when the smaller two chambers at the top of the heart (the left and right atria, who normally make up the ‘lub’ portion of ‘lub dub’) contract erratically and frantically.
AF can (but doesn’t always) cause a life-threatening disruption in the way the heart beats which may present with symptoms of shortness of breath, chest pain or feeling lightheaded.
Regardless of whether this happens, it always also causes turbulent blood flow.
The latter increases the risk of a clot developing, which, if it gets lodged in an artery in the brain, causes a stroke.
Other types of arrhythmia, while potentially being less common, can also be life-threatening. An example of this is Ventricular Tachycardia, or VT.
As described earlier, the heart and kidneys work closely together.
To recap, sometimes hypertension is caused by a problem with the kidneys. Other times, hypertension leads to a problem with the kidneys, known as Chronic Kidney Disease (chronic meaning something that has built up over time rather than happening suddenly).
Think of the kidneys a bit like a sieve.
The things caught in the sieve stay in the blood, and what is let through escapes in the urine.
Hypertension puts too much pressure on the sieve and can cause bigger holes to appear, meaning things get filtered through that shouldn’t, such as proteins.
(Hence why GPs often check for protein in the urine when hypertension is first diagnosed.)
Damage to the blood vessels in the kidney (atherosclerosis again!) means that they just can’t filter as well as they should, and a lot of fluid that should go in the urine actually stays in the blood.
This extra fluid in the blood vessels can make the blood pressure rise higher, causing a vicious cycle. When this gets particularly bad, it might be labelled as Kidney Failure.
We know that hypertension increases the risk of developing Dementia.
It is thought that this occurs when a rise in pressure damages the barrier between the blood and the brain.
This then leads to protein leaking into the brain, which can damage and kill brain cells.
Multiple studies have shown that hypertension is linked with volume reduction in the brain.
The medical term for this is hypertensive retinopathy – opathy meaning ‘disease of’, retina referring to the back of the eye.
If this is present, and the blood pressure isn’t treated, it can sadly lead to loss of vision ‘within a short period of time’.
While Erectile Dysfunction can have a variety of causes, it is not uncommonly due to problems with the blood supply to the penis.
Raised blood pressure can cause damage to the arteries here (atherosclerosis), just like elsewhere in the body, meaning less blood can get through.
Assessing and treating ED properly should therefore include checking the blood pressure and cholesterol, not just taking Viagra.
While it may feel somewhat depressing or overwhelming to read through a list of possible complications, it’s important to remember that the risk of getting these conditions is hugely reduced by getting your blood pressure under control.
Hopefully, that’s a somewhat motivating thought. Of course, once diagnosed with hypertension, it is useful to check your blood pressure periodically to see how well controlled it is.
And of course, if it remains above the target you set with your GP (again, for those without other medical conditions, under the age of 8yo, you typically want it well below 135/85 for home readings – ideally closer to 120/80), it’s important to speak to your GP about it and review your management plan together.
There are other things that should be monitored periodically alongside your blood pressure control. These include:
- Monitoring for damage from hypertension: checking annual urine samples and kidney blood tests to check for protein leaking through the kidneys, checking the back of the eyes, etc.
- Monitoring for other risk factors of the complications mentioned. A common theme of the disease mentioned in the above list is those fatty deposits inside the blood vessels, atherosclerosis. Raised cholesterol and sugar levels increase the chance of atherosclerosis happening and should be assessed regularly. Your GP will have done this when you were first diagnosed with hypertension, and likely annually thereafter but if you were curious in-between tests, you can use our Healthy Heart home blood test kit.
- Monitoring for damage from medication. Some of the medicines used to treat hypertension carry their own risks of damage. Generally, these risks are thought to be much lower than the risk of not treating a raised blood pressure, but typically they will require periodic blood tests. For instance, when someone is first starting an ACE-Inhibitor, or increasing their dose, they should have their kidney function blood tests done prior to starting, then repeated after about 1-2 weeks, then done regularly afterwards.
Hypertension is a major risk factor for several serious, life-threatening and life-altering conditions.
Half of the people with it don’t know they have it, as it doesn’t typically give symptoms.
It is easy to check and there are effective ways to lower it and reduce the risk of developing a major complication if it’s raised. If you have any questions about your own blood pressure, please do speak to a GP or visit BPassoc.org.uk.
|ABPM||Ambulatory Blood Pressure Monitoring|
|Artery||Blood vessel carrying blood away from your heart|
|Atherosclerosis||Fatty deposits on the inside wall of an artery|
|Blood Vessel||Generic term for arteries and veins (typically used in this article to mean artery)|
|Cardiac||To do with the heart|
|HBPM||Home Blood Pressure Monitoring|
|Hypertension||High blood pressure|
|Hypotension||Low blood pressure|
|NICE||National Institute of Health and Clinical Excellence|