Dizziness (lightheadedness) is a common symptom that’s not usually a sign of anything serious, but should be investigated by a doctor.
The term "dizziness" means different things to different people – some use it to describe feeling lightheaded or off balance, while others use it to describe a feeling that their surroundings are spinning.
Because the symptom is quite vague and can be caused by a wide range of things, it may not always be easy to identify the underlying cause.
This page explains what you should do if you feel dizzy for no apparent reason, and outlines the most common causes.
When to seek help
Your GP will want to establish exactly what you mean by dizziness, and check that you're not actually describing vertigo – a severe type of dizziness, where you feel your surroundings are spinning or moving.
They’ll also want to know:
- whether the dizziness started for no apparent reason, or if it followed an illness
- whether you have repeated episodes of dizziness and, if so, when you tend to experience these
- how long the dizziness lasts
Dizziness can sometimes be caused by an ear condition. A simple way of distinguishing between ear-related dizziness and dizziness due to other causes is to determine whether it occurs only when you're upright or also when you're lying down.
If feeling dizzy occurs when you're upright is probably not related to the ear. Dizziness that happens when you're lying down is usually caused by a viral ear infection, which can't be treated with antibiotics.
It’s a good idea to keep a diary recording when and where you experience dizziness and take it with you to your GP appointment. It's helpful to note:
- what you were doing at the time you felt dizzy
- how long it lasted and how bad it was
- whether you had any other symptoms – such as fainting, vomiting, nausea, blurred vision, headache, hearing loss or tinnitus
If you're taking prescription medicine, your GP will probably review this to check whether dizziness is a possible side effect. If necessary, they can prescribe a different medication for you to try.
You may be referred to a specialist for further tests and investigations.
Common causes of dizziness
The most common causes of dizziness are:
- labyrinthitis – an inner ear infection that affects your hearing and balance, and can lead to a severe form of dizziness called vertigo
- migraine – dizziness may come on before or after the headache, or even without the headache
- stress or anxiety – particularly if you tend to hyperventilate (breathe abnormally quickly when resting)
- low blood sugar level (hypoglycaemia) – which is usually seen in people with diabetes
- postural hypotension – a sudden fall in blood pressure when you suddenly sit or stand up, which goes away after lying down. This is more common in older people
- dehydration or heat exhaustion – dehydration could be due to not drinking enough during exercise, or illness that causes vomiting, diarrhoea or fever
- vertebrobasilar insufficiency – decreased blood flow in the back of the brain, which may be caused by the blood vessels that lead to the brain from the heart being blocked (known as atherosclerosis)
Less common causes of dizziness
Less common causes of dizziness include: