Our Symptom checker provides clinical advice on what to do next based on your symptoms.
If you have fainted, or if you’re looking after somebody who has fainted, information in 'Fainting treatments’ may be helpful for easing the symptoms.
Fainting is a period of temporary loss of consciousness that happens when the blood flow to the brain is reduced.
Collapsing has a range of causes, often occuring because someone has fainted. You collapse when your brain isn't getting enough oxygen.
A blackout is a temporary loss of consciousness. A common cause of a blackout is fainting, but can be caused by a serious health condition. Treatment will depend on the cause of your blackout. Learn more here.
Have you felt light-headed, unsteady or weak recently? Read on for helpful advice about 'dizzy spells', causes of dizziness and what to do when feeling faint.
Lightheadedness is common in older adults and usually improves if you drink some water and lie down. But it can also be a symptom of something more serious.
This condition can disrupt the rhythm of your heart. It can cause palpitations, fainting or, in serious cases, cardiac arrest.
Bradycardia is a slower than normal heart rate, which can lead to a range of symptoms such as feeling faint, tired or short of breath.
Heart arrhythmias are irregular heartbeats. The heart can beat too fast, too slow or irregularly — learn how to recognise the symptoms here.
Long QT syndrome
Long QT syndrome (LQTS) is a disorder of the heart's electrical system that can cause fast, chaotic heartbeats, called arrhythmias.