This factsheet is for people who have low blood pressure (hypotension), or who would like information about it including the symptoms, causes and treatments.
If you have low blood pressure, this means that it’s lower than would usually be expected for a particular person and may cause symptoms such as fainting. Although it's usually good for health to have as low a blood pressure as possible, when it becomes too low it can cause a reduction in blood flow around your body.
Your blood pressure is a measure of the force that your blood puts on the walls of your arteries as it's pumped around your body by your heart. This is affected by the strength with which your heart pumps, and the size and flexibility of your arteries that carry the blood.
Blood pressure is expressed as two numbers, such as 120/80mmHg (millimetres of mercury). The first number shows the maximum pressure when your heart contracts – this is your systolic blood pressure – and the second number shows the minimum pressure as your heart relaxes – this is your diastolic blood pressure.
If your blood pressure is too high, you will be at greater risk of certain diseases, such as coronary heart disease and stroke. Therefore, it's usually good to have as low a blood pressure as possible, as this can reduce your risk of getting these conditions. The ideal blood pressure for adults is between 90/60 and 120/80mmHg.
However, if your blood pressure falls below what is usual for you, it may be that there isn’t enough blood being pumped around your body. This may mean that the flow is restricted to organs including your brain, which can lead to symptoms such as fainting.
There is no recognised level for low blood pressure. If your systolic blood pressure is lower than 90, your GP may consider it to be low. However, a blood pressure below this may be normal for some people, whereas others may develop symptoms of low blood pressure at a level above this. It also depends on other factors – for example blood pressure is lower in young women and especially in pregnant women. It's therefore only considered to be a problem if you’re having symptoms.
If your blood pressure is naturally low, you’re unlikely to have any symptoms and it's not something you should be concerned about.
However, if your blood pressure becomes lower than usual for you, it can cause symptoms such as:
You may find that you mainly get these symptoms when you stand up from a sitting position or from lying down, usually within the first few seconds or minutes. This is called postural (orthostatic) hypotension. If you tend to get symptoms after eating a meal, it's called postprandial hypotension.
Seek medical advice as soon as possible if you have any of the symptoms of low blood pressure.
If your blood pressure has been described as low but you don't have any symptoms, there is unlikely to be any underlying problem, and this is a healthy blood pressure for you.
Anyone can occasionally get a sudden, temporary drop in blood pressure that causes symptoms, such as fainting. A number of things can cause this, for example:
However, if you have low blood pressure that is regularly causing symptoms, it may mean that the mechanisms that control blood pressure in your body aren’t working as they should be, causing your blood pressure to drop.
If you have postural hypotension, your body doesn't respond quickly enough when you stand up, causing blood to pool in your legs. This means that less blood goes back to your heart so there isn’t as much for it to pump out, causing blood pressure to fall. Postprandial hypotension happens when blood flows to your digestive system after you eat a meal but your body doesn't respond in the usual way to maintain blood pressure in the rest of your body. Both of these conditions are more common in older people.
There may be an underlying condition that is causing your low blood pressure. These include:
Your GP will ask about your symptoms and examine you. He or she will measure your blood pressure using a device called a sphygmomanometer. This is usually an automated, digital device, consisting of a monitor attached to a cuff, which is wrapped around your upper arm. Your GP will press a button to inflate the cuff, and then it will automatically slowly deflate. A sensor in the cuff detects your pulse when the cuff is fully inflated and as it deflates, and converts this into a measurement of blood pressure – the result is shown on the display screen.
If you have symptoms of postural hypotension, your GP may also measure the change in your blood pressure as you stand up after sitting. If it’s much lower when you stand up compared with when you’re sitting down, this suggests you have postural hypotension. Your GP may also refer you for a tilt test. This happens in hospital and involves being slowly tilted from lying down to an upright position on a table as your blood pressure and heart rate and rhythm are monitored. See our frequently asked questions for more information.
You’re unlikely to need any treatment if your blood pressure is naturally low and you don't have any symptoms.
If you have symptoms, your treatment will depend on the cause of your low blood pressure. For example, if you’re taking medicines to treat high blood pressure and these are causing your blood pressure to drop too much, your GP may suggest stopping or changing your medication. He or she will also check that you’re receiving the right treatment for any other underlying conditions, such as diabetes or Parkinson's disease.
There are several self-help measures that can help if you have either type of hypotension.
If you have postural hypotension, your GP may advise you to:
Your GP may advise you to alter your diet so it includes more salt. However, don't do this unless your GP advises you to as it needs to be done in a controlled way.
If you have postprandial hypotension, your GP may advise you to:
These measures may not be suitable for everyone. Ask your GP about what is right for you.
Occasionally, your GP may prescribe medicines if self-help measures don’t stop your symptoms of low blood pressure. These may include medicines that:
Your GP may refer you to a specialist for further tests before prescribing these medicines, or if they are not helping.
Produced by Polly Kerr, Bupa Health Information Team, September 2012.
For answers to frequently asked questions on this topic, see FAQs.
For sources and links to further information, see Resources.
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This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.
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