If you get low blood pressure, there may not be enough pressure to pump blood properly around your body. The supply of oxygen to your vital organs, including your brain may be restricted. This can cause symptoms such as dizziness and fainting. Treatment, if you need it, will depend on the cause of your low blood pressure and may just involve some simple lifestyle changes.
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. Your blood pressure changes throughout the day. It’s lower when you sleep, and rises when you wake up.
You’ll see blood pressure shown as two numbers, such as 120/80mmHg. The first number is the pressure when your heart contracts – your systolic blood pressure. The second number is the pressure as your heart relaxes – your diastolic blood pressure. The letters ‘mmHg’ mean millimetres of mercury, the units used to measure blood pressure.
If your blood pressure is too high (hypertension), you may be at greater risk of certain diseases such as coronary heart disease and stroke. The ideal blood pressure for adults is between 90/60 and 120/80mmHg.
There’s no recognised cut-off level for low blood pressure that applies to everyone. For instance, a systolic pressure of 90 may be too low for some people, but normal for many young, healthy adults. Low blood pressure is only considered to be a problem if you’re having symptoms.
When your blood pressure drops below what’s normal for you (hypotension), it can cause symptoms. The main types of hypotension are listed here.
- Postural (orthostatic) hypotension. If you have postural hypotension, your body doesn't respond quickly enough when you stand up, causing blood to stay in your legs. So less blood goes back to your heart and there isn’t as much for it to pump out, causing your blood pressure to fall. Postural hypotension is common, especially in older people, affecting nearly one in three adults over 65. It’s more likely to happen if you’re taking certain medicines, are dehydrated or you have spent a long time in bed or you’ve had a hot bath.
- Postprandial hypotension. Postprandial hypotension happens when blood flows to your digestive system after you eat a meal. Your body doesn't respond in the usual way to maintain blood pressure in the rest of your body. Symptoms may happen within two hours of eating, but usually sooner. This is another common type of hypotension which mainly occurs in older people.
- Neurally mediated hypotension. This is also called reflex syncope (fainting). This is an occasional sudden, temporary drop in blood pressure causing symptoms such as fainting. The medical term for this is syncope. This can happen if you’ve been standing for a long time. It can also be triggered by pain, emotional stress or fear (such as if you have a phobia). Around half of us will get this at some point in our lifetime.
- Severe hypotension (shock). This is a life-threatening condition where your blood pressure drops very low and your vital organs don’t get the blood they need. It can happen in a number of serious medical conditions. These include severe infections, heart attack, severe allergic reactions or major blood loss. If you have severe hypotension, you need immediate medical attention.
There may be an underlying medical condition that’s causing your low blood pressure. Examples include heart disease, Parkinson’s disease and diabetes (see our FAQ ‘Diabetes and hypotesion’ for more information). You may also get low blood pressure during pregnancy.
Your GP will be able to tell you more about the type of low blood pressure you have, and what might be causing it.
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:
- dizziness or light-headedness
- palpitations (you can feel your heart beating more forcefully)
- feeling sick
- blurred vision
- feeling confused or unable to concentrate
You may find that you mainly get these symptoms when you stand up from a sitting position or from lying down. This usually happens 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.
If you have been having symptoms like the above, contact your GP. It might be better to ring them first before making an appointment as it may be they can offer advice over the phone. They may advise that they need to see you to check for any underlying causes.
Your GP will ask about your symptoms and examine you. They’ll measure your blood pressure using a device called a sphygmomanometer. This may be an automated digital device or they may use a manual device.
If you have symptoms of postural hypotension, your GP may also measure the change in your blood pressure while you’re sitting (or lying) and then standing. 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 recommend that you have some blood tests to check your general health. If they think that your low blood pressure may be linked to an underlying problem with your heart, they may offer you further tests. These may include an electrocardiogram (ECG) and an echocardiogram (ultrasound of your heart).
If your GP refers you to a hospital specialist, they may recommend a test called a tilt test to understand what’s causing your symptoms. It involves being slowly tilted from lying down to an upright position on a table as your blood pressure, heart rate and rhythm are monitored. See our FAQ ‘Tilt test’ for more information.
There are some simple steps you can take to help limit the symptoms of common types of low blood pressure.
If you have postural hypotension and get symptoms when you sit up or stand, your GP may suggest some of the actions described below.
- Stand up slowly from sitting or lying down, especially when you first wake up.
- Consider crossing your legs while standing, standing on tip toes and tensing your muscles. This can help your blood flow back to your heart more quickly and reduce symptoms when standing up. However, these actions may not be suitable for everyone – leg crossing and standing on tip toes could be risky for people with poor balance.
- Take care getting out of hot baths or showers.
- Make sure you drink plenty of fluid. If you drink alcohol, stick to the recommended daily limits. This means not regularly drinking more than 14 units over the course of a week. If you do drink as much as 14 units, you should spread it over three days or more, rather than 'saving up' units. Have some alcohol-free days too.
- Raise the head of your bed a little.
Your GP may also suggest that you alter your diet so it includes more salt. However, don't do this unless they advise you to, because increasing your intake of salt needs to be done in a controlled way.
Compression stockings might also be advised by your GP. These can help stop blood staying in your legs.
If you have postprandial hypotension, getting symptoms after eating a meal, your GP may make the following suggestions.
- Eat smaller meals more frequently, with less carbohydrate (that is, less starchy food such as rice, bread and pasta). This may be better than fewer, large meals with lots of carbohydrate.
- Lie down, or at least avoid sudden standing after a meal.
These measures may not be suitable for everyone. Ask your GP about what’s right for you.
Remember – if you feel faint, you should immediately sit or lie down if you can do so safely. Put your feet up so that they are higher than the level of your heart. If your symptoms don’t go away, seek medical attention.
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, there are usually simple things you can do to help yourself. See our section ‘Self-help for low blood pressure’.
Sometimes, low blood pressure can be caused by the medicines you’re taking. Your GP may review your medicines to see if there are any that could be making your symptoms worse or bringing them on. They may suggest stopping or changing your medication to see if that helps. It’s important that you don’t stop or change any of your medicines without discussing it with your GP first.
Occasionally, your GP or a specialist may prescribe medicines if self-help measures don’t stop your symptoms of low blood pressure. These may include medicines that:
- increase how much salt is in your body
- make your veins constrict
A tilt test can help to find out what may be causing symptoms such as fainting and dizziness. During the test, you lie on a special table and are slowly tilted upwards. This is so a doctor can monitor your blood pressure and heart rate as you move from lying down into an upright position.
A tilt test is usually done as an outpatient appointment. This means you’ll go to hospital to have the test but you won't need to stay overnight.
When you go for the test, you’ll be asked to lie down on the tilt table, which has a footrest at the bottom. Safety belts will be placed around your body to keep you secure. Wires, called electrodes, will be attached with sticky patches to your chest so that your heart rate and rhythm can be monitored. A small cuff will be placed around your arm to monitor your blood pressure.
Your blood pressure and heart rhythm are recorded while you’re lying down on the table. The table will then be gradually tilted until you’re almost in an upright position. You’ll probably stay like this for up to 45 minutes while your blood pressure and heart rhythm are monitored. You may also be given a medicine to help improve the accuracy of the test.
At the end of the test, you’ll be lowered back down into a lying position.
You may start to get symptoms during the test, such as sweating or feeling light-headed or sick. It’s also possible that you may faint during the test. If this happens, the bed will be returned to a flat position to allow you to recover.
The results of your test will be reported to your doctor so they can discuss them with you at your next appointment.
Having diabetes can cause damage to your nerves. When this affects the nerves in the part of the nervous system that regulates blood pressure, it can cause postural hypotension. This is a drop in blood pressure when you stand up.
When you stand up, your body has to make some changes to stop your blood staying in the lower half of your body. These are quite normal and include an increase in your heart rate and constriction (narrowing) of the blood vessels in your legs. If the nerve supply to the blood vessels in your legs isn’t working properly, they can’t constrict as well as they should. This means that blood pools (stays) in your legs, reducing the amount that reaches your brain and causing symptoms such as fainting and dizziness. This is postural hypotension.
Both type 1 and type 2 diabetes can damage your nerves, which carry signals from your brain to all parts of your body. This is called diabetic neuropathy. One type of diabetic neuropathy can affect the nerves to your blood vessels, so preventing them from constricting when you stand. So, if you have diabetes, you may be more likely to get the symptoms of postural hypotension.
Doctors don't fully understand why diabetes damages nerves – there are probably several factors involved. If you have diabetes which isn’t well controlled, you will have high levels of glucose (sugar) in your blood. This can cause chemical changes in your nerves, affecting how they transmit signals.
This is one of the reasons why it's important that you take care to control your diabetes properly.
Having blood pressure which is too high is a risk to your health. High blood pressure puts an increased strain on your arteries which can lead to serious conditions such as stroke, coronary heart disease and kidney failure. The lower your blood pressure, the less likely you are to suffer from these problems.
However, if your blood pressure becomes too low, which means lower than is normal for you, then it can cause problems. You may become unsteady and even faint.
There are a lot of things you can do to help keep your blood pressure in a healthy range. These include:
- keeping physically active
- stopping smoking
- limiting how much salt you eat
- eating a healthy diet
- drinking only moderate amounts of alcohol
It’s best to have your blood pressure checked regularly (at least every five years) and follow your GPs advice about how to keep it at a healthy level.
It’s not unusual to have low blood pressure during early and mid pregnancy. This may make you feel faint, especially when you stand up quickly. By itself, low blood pressure doesn’t harm your baby, and it usually stops after your baby is born. It’s always best to tell your midwife or doctor about any new symptoms you have.
Your midwife will check your blood pressure at each antenatal appointment. This is just part of making sure you and your baby are healthy.
It’s important for your midwife and your doctor to know if you’re developing high blood pressure. That’s because high blood pressure in pregnancy can lead to the medical conditions pre-eclampsia and eclampsia. These may be harmful to you and your baby.
It’s normal for your blood pressure to become lower during pregnancy. This is mainly because your hormones relax the walls of your blood vessels. Your blood pressure may fall very early in your pregnancy and reach its lowest point during your second trimester (around 24 weeks). It then starts to rise again, returning to normal by about 36 weeks.
If you have low blood pressure during pregnancy, you may feel faint and dizzy suddenly when you get up from lying or sitting. This is called postural hypotension. See our section ‘Types and causes of low blood pressure’ for more information.
You can help relieve your symptoms of postural hypotension by making sure you get up slowly from lying or sitting. If you feel you’re going to faint, it’s important to sit or lie down right away. See our section ‘Self-help for low blood pressure’ for more tips on coping with low blood pressure.
Towards the end of your pregnancy when your baby is quite large, you may feel faint when lying on your back. This is because then your baby presses on the main vein returning blood to your heart. You can help prevent this by lying on your side.
By itself, having low blood pressure during pregnancy doesn’t seem to cause any harm to your baby. The symptoms usually go away after your baby is born.
Occasionally, symptoms of low blood pressure are caused by other underlying health conditions affecting your pregnancy. Always tell your midwife about your symptoms. Seek medical help if you have dizziness or fainting, or any other symptom that you’re worried about.
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