The words "high blood pressure" and "hypertension" mean the same thing and both terms are used throughout this site

What is high blood pressure?

There is no such thing as the ideal or normal blood pressure reading. Some heart specialists say that – if you are on hypertension or blood pressure treatment – then your target level (or the “best” reading to aim for) - is the lowest level you can tolerate without feeling light headed, faint or dizzy.

At least one cardiologist I know aims to have his high BP treatment patients feel “just a little light headed” if they get up quickly from a chair. He knows that if they feel like this their blood pressure reading is low enough to improve their cardiovascular health. But if the actual BP reading was any lower they would be at risk of blacking out or falling over – so take care if you feel like this on your treatment!

What is high blood pressure measurement
The machine used to measure high BP is called a sphygmomanometer.

Old-fashioned versions of these machines were filled with a column of liquid mercury – a bit like the sort of thermometer that your grandmother might have used under your tongue or under your arm to check your temperature. Because of this historical measuring method, BP measurements are still given today in millimetres of mercury or mmHg for short (Hg is the chemical symbol for mercury).

Two numbers are always used to describe your BP reading. The first number refers to the Systolic Blood Pressure and the second number relates to the Diastolic Blood Pressure. A typical reading might be written in your doctors notes as BP = 145 / 75 mmHg. This means that the systolic reading is 145 millimetres of mercury and the diastolic reading is 75 millimetres of mercury. When speaking about these numbers your doctor might say “one hundred and forty five over seventy five” – using the word “over” in place of the slash between the numbers

If you are interested in measuring your own level at home then take a look at the blood pressure monitor section of this website.

What is a blood pressure symptom?

This question is often asked. Does high blood pressure cause any particular symptom or pattern of symptoms. Often the answer is no - and the lack of any predictive high BP symptom is one reason why many people who have high BP live for years without having it detected.

However, while it's true that there is no one single symptom of a high blood pressure, there are a group of symptoms that might indicate that you need a BP check. These are shown in the table at the foot of this page.

Systolic Pressure

The systolic pressure measures the force that the heart uses when it contracts and pushes the blood round the arteries of the body. The systolic level is the higher of the two numbers recorded.

Diastolic Pressure

The diastolic pressure measures the force that is needed to fill up the heart as it relaxes and gets ready for its next contraction. The diastolic level is the lower of the two numbers recorded.

Pulse Pressure

Pulse pressure is calculated by subtracting the diastolic reading from the systolic reading. So with a BP reading of 145 / 70 then the pulse pressure would be equal to 145 minus 70 or 75.

Many experts worldwide now regard pulse pressure as an important predictor of hypertension related problems in later life. Pulse pressure can be used as a measurement of how “stiff” or inflexible the artery blood vessel walls are. Healthy arteries have flexible and elastic walls – diseased arteries are stiff and inflexible.

Some studies suggest that - if the pulse pressure increases by 10 mmHg in people over 45 years old then:

•  the risk for stroke increases by 11%

•  the risk for heart disease increases by 10%

•  and overall mortality increases by 16%

So, again: What is High Blood Pressure?

High blood pressure is officially defined as a systolic reading of more than 140 mmHg or a diastolic reading of more than 90 mmHg – or both systolic more than 140 and diastolic more than 90.

There is now good evidence that those with BP readings above these levels are at risk of stroke or heart disease.

Please don't get complacent however if your reading is below 140 / 90. Blood pressure exists along a spectrum and can vary throughout life. 135 / 85 is acceptable but 115 / 70 is better and 110 / 60 better still. Some very fit individuals may have a BP reading of around 90 / 60 – but any lower than this is likely to cause symptoms related to low BP, typically dizziness or fainting.

Blood pressure also varies during the day and will normally drop a bit after you have been sitting for a while – it should drop a lot when you are asleep at night. Some hypertension patients do not seem to show this “night time dipping” or dropping in their levels. These people are at high risk of complications.

Try not to get too confused with all of this. Just keep gradually reading around the subject and you'll eventually develop a deep understanding of how high BP can affect your health.

The table below shows the different levels of blood pressure and what they mean for you.

High Blood Pressure Symptoms

The symptom list in this table is drawn from the commonest type of high BP symptom that people experience. By its nature it can never be comprehensive. If you feel unwell in any way you should see your doctor. A regular check up on your health and your BP is always a good idea. Remember - the commonest high blood pressure symptom is "no symptom at all" !!

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