Low Blood Pressure (Hypotension)
Low blood pressure (hypotension) overview
Blood pressure is the force of blood against the artery walls. It is written as two numbers, for example 120/80 mmHg. Blood pressure is generally considered low when it is below 90/60 mmHg. Many healthy people, particularly young, slim or very fit people, have a naturally low reading and feel completely well. Low blood pressure matters when it causes symptoms, falls suddenly, or is a sign of another problem.
Common types
- Postural (orthostatic) hypotension: a fall in blood pressure on standing, causing light-headedness.
- Post-meal (postprandial) hypotension: a fall after eating, more common in older people.
- Reflex (neurally mediated) hypotension: a sudden fall linked to triggers such as standing for long, heat or emotion, often leading to a faint (vasovagal syncope).
- Severe hypotension (shock): a dangerous fall with organ under-perfusion, which is a medical emergency.
Low blood pressure symptoms and signs
Many people with low blood pressure have no symptoms. When they occur, they are caused by too little blood reaching the brain and other organs.
Possible symptoms
- light-headedness or dizziness, particularly on standing (see dizziness)
- fainting or near-fainting (see fainting)
- blurred or greying vision
- weakness, fatigue and difficulty concentrating
- nausea
- palpitations (see palpitations)
Warning signs of severe hypotension
Cold, clammy or pale skin, rapid shallow breathing, a rapid weak pulse, confusion, chest pain or collapse need emergency care. Call 999.
Causes and risk factors of low blood pressure
Low blood pressure has many causes, from normal variation to serious illness.
Common causes
- dehydration, hot weather, prolonged standing or heavy alcohol intake
- medicines: blood pressure tablets, diuretics, nitrates, some antidepressants, medicines for prostate symptoms, and medicines for Parkinson’s disease
- heart conditions: a slow heart rate (see bradycardia), heart valve disease (see heart valve disease), heart failure and heart attack
- hormonal conditions: an underactive thyroid, low cortisol (adrenal insufficiency) and low blood sugar
- blood loss, anaemia, infection and pregnancy
- problems with the autonomic nervous system, including in diabetes and Parkinson’s disease, and conditions such as POTS
Who is at higher risk?
Older people, those taking several medicines, people with diabetes, and those who are dehydrated or have been unwell or in bed for a long time have a higher risk of postural hypotension.
When to see a doctor about low blood pressure
Call 999 if you collapse, have chest pain, severe breathlessness, confusion, cold clammy skin, or black or bloody stools or vomit.
Arrange an assessment if you:
- often feel dizzy or faint, particularly on standing
- have fallen or injured yourself after feeling faint
- have low readings and have been started on new medicines
- have symptoms with a heart condition, diabetes or Parkinson’s disease
- are unsure whether your low readings are normal for you
How low blood pressure is diagnosed
The assessment looks for the cause and for any heart problem.
1. History and medicines review
Your doctor will ask when symptoms occur, what medicines and fluids you take, and about any illness, bleeding or diabetes.
2. Lying and standing blood pressure
Blood pressure and pulse are measured after lying for 5 minutes, then at 1 and 3 minutes of standing. Postural hypotension is diagnosed when systolic pressure falls by 20 mmHg or more, or diastolic by 10 mmHg or more, within 3 minutes of standing. In POTS, the heart rate rises sharply on standing without a big fall in pressure.
3. Tests for a heart or other cause
A 12-lead ECG, an echocardiogram, blood tests (blood count, kidney function, glucose, thyroid and cortisol if indicated), home or 24-hour blood pressure readings, and heart rhythm monitoring may be needed. For unexplained fainting, a tilt table test may be considered.
Low blood pressure treatment options
Treatment depends on the cause. Low blood pressure without symptoms needs no treatment.
1. Treating the cause
Medicines are reviewed and, where possible, changed or reduced by the doctor who prescribed them. Please do not stop medicines yourself. Heart rhythm, valve problems, anaemia and hormonal causes are treated directly.
2. Self-help measures
- drink enough fluid, usually 1.5 to 2 litres a day unless you have been told to limit fluids
- stand up slowly, and pause sitting on the bed edge before standing
- avoid hot baths, long standing, large heavy meals and excess alcohol
- eat smaller, more frequent meals if you feel faint after eating
- raise the head of the bed slightly if you are prone to morning symptoms
- use physical counter-manoeuvres, such as crossing the legs and tensing the thighs, if you feel faint
3. Compression and medicines
Waist-high compression stockings or abdominal binders can help some people. Extra salt should only be used on medical advice, particularly if you have heart disease or high blood pressure. In selected people with severe postural hypotension, specialists may prescribe medicines such as fludrocortisone or midodrine.
Living with low blood pressure
Most people manage low blood pressure with simple measures.
Practical steps
- Keep a diary of symptoms, home blood pressure readings and triggers.
- Carry water in hot weather and when travelling.
- Sit or lie down at the first sign of faintness to avoid falls.
- Review your medicines with your doctor at least once a year.
Driving and work
If you have had a faint, the DVLA may need to be told, depending on the cause and circumstances. See DVLA cardiac assessment.
Low blood pressure prognosis and outlook
The outlook depends on the cause. A naturally low blood pressure without symptoms is not harmful. Postural hypotension caused by dehydration or a medicine usually improves when the cause is corrected. When it is caused by a long-term condition, it can be managed but may need continuing treatment. Falls are the main practical risk, particularly in older people.
Low blood pressure key facts
- Low blood pressure is generally defined as below 90/60 mmHg.
- Many healthy people have naturally low readings.
- It needs attention if it causes symptoms such as dizziness or fainting.
- Postural hypotension is a fall of 20/10 mmHg or more on standing.
- Medicines, dehydration and heart conditions are common causes.
Guidelines and sources
This page follows the 2018 ESC guidelines for the diagnosis and management of syncope, the consensus definition of orthostatic hypotension (Freeman et al., 2011) and NHS patient information.
Low blood pressure questions and answers
Is low blood pressure bad for the heart?
A naturally low reading with no symptoms is not harmful. It matters when there are symptoms or an underlying cause.
Should I stop my blood pressure tablets if my reading is low?
Please do not stop them yourself. Tell the doctor who prescribed them about your readings and symptoms.
Can low blood pressure cause fainting?
Yes. A sudden fall in blood pressure or heart rate is a common cause of fainting.
Can I raise my blood pressure with salt?
Only on medical advice. Extra salt can be harmful if you have heart disease, kidney disease or high blood pressure.
Is low blood pressure the same as POTS?
No. In POTS the heart rate rises sharply on standing, often without a fall in blood pressure.
Can I have this assessed privately?
Yes. A face to face consultation can include blood pressure lying and standing, an ECG and an echocardiogram.
Questions to ask your cardiologist about low blood pressure
- Is my blood pressure low for me, or is it a sign of a problem?
- Could any of my medicines be responsible?
- Do I need a heart scan, rhythm monitoring or other tests?
- Could a heart rhythm problem or a heart valve condition be contributing?
- Should I check my blood pressure at home, lying and standing, and how?
- Should I change how much fluid, salt, alcohol or caffeine I have?
- What can I do to prevent symptoms and falls?
- Is it safe to drive and exercise?
- Is it likely to improve or change over time, and when should I be reviewed again?
- When should I seek urgent help?
If you feel dizzy or faint, particularly on standing, or have a repeatedly low blood pressure reading. You can book a video consultation or telephone consultation from anywhere in the UK, or a face to face consultation in Peterborough or Corby. A 12-lead ECG and echocardiogram can be arranged to look for a heart cause.
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Medically reviewed by Dr Salam Salloum, Consultant Cardiologist. Last reviewed: . This page is for general information and does not replace personal medical advice.