Low Blood Pressure (Hypotension): Symptoms, Causes and What to Do When You Feel Faint

Low blood pressure (hypotension) is generally a reading below 90/60 mmHg. For many healthy people, especially young and active adults, low blood pressure causes no problems. It matters when it causes symptoms such as dizziness, light-headedness, blurred vision or fainting, or when it is caused by an underlying problem such as dehydration, bleeding, infection or medicines.

Symptoms

• Dizziness or light-headedness, especially when standing up
• Fainting
• Blurred vision
• Feeling weak, tired or confused
• Nausea

Types

• Postural (orthostatic) hypotension: a drop when standing up, common in older adults and people on blood pressure medicines
• After meals (postprandial): dizziness after eating, mainly in older adults
• Neurally mediated (vasovagal): fainting after standing a long time, heat, pain or the sight of blood
• Shock: dangerously low blood pressure from severe bleeding, infection (sepsis), allergy or heart problems; an emergency

Common causes

• Dehydration, hot weather, vomiting or diarrhoea
• Medicines: blood pressure tablets, diuretics, some antidepressants, Parkinson’s medicines, erectile dysfunction tablets with nitrates
• Pregnancy (especially the first 24 weeks)
• Prolonged bed rest
• Heart problems, endocrine problems (e.g. adrenal insufficiency), diabetes-related nerve damage
• Blood loss and anaemia

What to do if you feel faint

1. Sit or lie down immediately
2. Raise your legs if lying down
3. Drink water once you feel better
4. Stand up slowly: sit on the edge of the bed first

Self-care tips

• Drink enough fluids, especially in hot weather and on long shifts
• Stand up slowly and avoid standing still for long periods
• Eat smaller meals if dizzy after eating
• Limit alcohol
• Compression stockings may help some people
• Ask your healthcare provider to review your medicines; never stop them yourself

Seek emergency help if low blood pressure comes with

• Chest pain or breathlessness
• Confusion, cold clammy skin, fast weak pulse
• Fever and feeling very unwell (possible sepsis)
• Black stools or vomiting blood
• Fainting with injury, or fainting during exercise

For nurses

Measure lying and standing blood pressure when patients report dizziness or falls: a drop of 20 mmHg systolic or 10 mmHg diastolic within 3 minutes of standing suggests postural hypotension. Review fluid balance and medicines, and escalate low blood pressure with other abnormal observations using NEWS2.

Frequently asked questions

Is low blood pressure better than high blood pressure?

Without symptoms, low blood pressure is often a sign of good cardiovascular health. With symptoms, it needs assessment.

What should I eat or drink for low blood pressure?

Fluids help most. Some people are advised to increase salt, but only on medical advice.

Related reading: How to measure blood pressure · Types of shock · Falls prevention

Checked against NHS guidance on low blood pressure. Updated 5 November 2026.