Quick answer
What is low blood pressure?
Low blood pressure (hypotension) is a reading below 90/60mmHg. For many healthy people it causes no problems and needs no treatment. It matters when it causes symptoms — dizziness, lightheadedness or fainting, especially on standing — or when it results from dehydration, medicines, or another condition. See a GP if you keep feeling dizzy or faint.
What counts as low blood pressure?
Blood pressure is written as two numbers — the pressure when your heart beats (systolic) over the pressure between beats (diastolic). A reading below 90/60mmHg counts as low. Plenty of healthy people — particularly younger, active people — live at these levels with no symptoms and no ill effects, which is why doctors treat the symptoms, not the number.
Symptoms to watch for
Low blood pressure matters when it causes:
- dizziness or lightheadedness, especially on standing
- blurred vision or feeling faint
- fainting (syncope)
- weakness, tiredness or difficulty concentrating
Symptoms that appear on standing up are called postural (orthostatic) hypotension — the most common pattern, and more frequent with age.
Common causes
- Dehydration — heat, illness, vomiting or diarrhoea, or simply not drinking enough
- Medicines — blood pressure treatments, water tablets (diuretics), some antidepressants and Parkinson’s medicines
- Pregnancy — blood pressure commonly dips in the first and second trimesters
- Heart problems — a slow heart rate, valve problems or heart failure
- Hormone conditions — thyroid or adrenal gland problems
- After meals — blood diverted to digestion can drop pressure in older people
A sudden, severe drop — from major bleeding, serious infection (sepsis) or a severe allergic reaction — is an emergency, but it comes with obvious serious illness.
How it is diagnosed and treated
Your GP will measure blood pressure lying or sitting and again after standing, review your medicines, and may arrange blood tests or an ECG. Treatment targets the cause: adjusting a medicine, treating dehydration or an underlying condition, and practical steps — standing up slowly, avoiding long periods of standing, drinking enough fluids and eating smaller, more frequent meals. Medicines to raise blood pressure are rarely needed.
Common questions about low blood pressure
- What causes low blood pressure?
- Often nothing — some people naturally run low, especially if young and fit. Other causes include dehydration, standing for long periods, pregnancy, some medicines (blood pressure tablets, antidepressants, water tablets), heart problems, and hormone conditions such as an underactive adrenal gland. Blood pressure also naturally dips after meals and on standing quickly, particularly in older people.
- Why do I feel dizzy when I stand up?
- A brief head rush on standing is usually postural (orthostatic) hypotension — gravity pulls blood into your legs faster than your circulation adjusts. It is more common with age, dehydration, and certain medicines. Stand up slowly, sit on the edge of the bed first, and drink enough fluids. If it keeps happening or causes falls or fainting, see your GP.
- Is low blood pressure dangerous?
- Usually not — unlike high blood pressure, it does not damage your heart or arteries over time. The main risk is injury from dizziness, falls or fainting, especially in older people. Sudden, severe drops caused by serious infection, bleeding or allergic reactions are medical emergencies — but these come with obvious illness, not everyday readings.
- How can I raise low blood pressure?
- Drink plenty of fluids, stand up slowly, avoid standing still for long periods, and eat smaller, more frequent meals if pressure dips after eating. If a medicine is the cause, your GP may adjust the dose — never stop a prescribed medicine yourself. Most people need no treatment; salt intake should only be increased on medical advice.