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Fainting
Category: Brain & Nerves · All brain & nerves symptoms
What it can feel like
Fainting (syncope) is a brief loss of consciousness caused by a temporary drop in blood flow to the brain — you go limp, fall, and recover quickly and completely, usually within a minute or two, often after warning sensations of warmth, nausea, sweating and tunnel vision.
Possible causes
A symptom can have many causes, and most are not serious. The lists below group conditions this symptom can be associated with — common causes first. They are possibilities to discuss with a clinician, not a diagnosis.
Common causes
Fainting can be associated with pain, fear, the sight of blood, standing for long periods in heat, dehydration, and straining — the common reflex (vasovagal) faint. Blood pressure medicines and low blood sugar also contribute.
Other possible causes
Fainting can also be associated with heart rhythm problems and structural heart disease (notably fainting during exertion or while lying flat, or with palpitations or chest pain), with blood loss, and with seizures when the episode includes prolonged shaking, tongue biting or confusion afterwards.
Red flags — when to seek help promptly
- Fainting during exercise, or while lying down
- Fainting with chest pain, palpitations or breathlessness
- Fainting with no warning at all, causing injury
- Fainting in someone with known heart disease or a family history of sudden death at a young age
- An episode with prolonged shaking, tongue biting or confusion lasting more than a few minutes
What a clinician may do
A clinician will take a careful witness history (what bystanders saw is gold), check blood pressure lying and standing, and arrange an ECG and blood tests. Selected cases get heart rhythm monitoring, an ultrasound of the heart, or tilt-table testing.
Watch: related videos
Examination and clinical videos from the MedicalVideos.com library relevant to this symptom. Some clinical footage is graphic — that is the nature of a medical video library.
Related guides on MedicalVideos.com
Frequently asked questions
How is a faint different from a seizure?
Faints are brief, with quick, clear recovery and usually clear triggers and warnings. Seizures more often have prolonged rhythmic shaking, tongue biting (especially the side), incontinence and minutes to hours of confusion or exhaustion afterwards. Witness descriptions separate them best.
Can I drive after fainting?
That depends on the cause and your local licensing rules — a simple reflex faint with a clear trigger often has no restriction, while unexplained, exertional or recurrent syncope usually does until assessed. Ask your clinician and check your licence authority's guidance before driving.
Related symptoms — Brain & Nerves
Browse the F section of the A–Z list or return to the Symptoms A–Z hub.