Fainting

Symptoms

The symptoms that precede blood flow—related fainting depend on the underlying cause. People who faint as a reaction to stress or fear often describe a preceding sense of warmth, nausea, upset stomach, or a cold sweat.

People whose fainting is a result of heart disease experience palpitations, shortness of breath, constriction, or pressure in the chest before fainting.

The timing of symptoms that precede fainting is determined by the underlying cause. When fainting is brought on by stress or fear, the symptoms usually last a few minutes before loss of consciousness. When underlying heart disease is responsible, symptoms usually occur only a few seconds before loss of consciousness.