SYMPTOMS

What are the specific symptoms of syncope?

Syncope, also known as "fainting" or "passing out," is a sudden, temporary loss of consciousness, often resulting in a fall from a standing or sitting position. The episode typically lasts for a very short duration, usually within seconds^[1].

Syncope is primarily caused by a reduction in blood flow to the brain. When cerebral blood flow decreases, the oxygen supply to the brain also diminishes, leading to temporary brain dysfunction.

What is the difference between syncope and dizziness?

Syncope is a transient loss of consciousness due to a temporary reduction in cerebral blood supply. During an episode, the patient loses muscle tone and collapses, unable to maintain a normal posture.

Dizziness, on the other hand, is a subjective sensation of imbalance, often described as a spinning or swaying of oneself or the surrounding environment. It is related to abnormalities in sensory nerve function and usually does not involve loss of consciousness^[1].

TREATMENT

How to relieve fainting?

Generally, fainting resolves on its own within seconds without additional intervention. When fainting occurs, the following steps can help prevent potential harm:

• Family or friends should immediately lay the person flat, ensure the airway is clear, elevate the legs slightly, and loosen any tight clothing.
• After regaining consciousness, the person should avoid standing up immediately to prevent another episode.

If fainting lasts too long (e.g., over 1 minute), seek medical attention promptly to identify the cause and receive targeted treatment.

DIAGNOSIS

What to do if you faint?

If you have no prior history of fainting and suddenly experience severe headache, rapid heartbeat, or dizziness that makes it difficult to stand, these may be warning signs of fainting. Immediately find support, such as leaning against a wall or pillar, and slowly squat or lie down. If no support is available, sit or lie down on the spot to avoid falling. Seek medical attention as soon as possible after regaining consciousness.

If you have a history of fainting and recent episodes have increased in frequency or duration, or if you notice blood in your stool, seek medical evaluation for a clear diagnosis.

What to do if someone else faints?

If you notice someone showing signs of fainting, such as unsteadiness but quick recovery, it may be orthostatic hypotension. Assist the person to prevent a fall.

If fainting is accompanied by any of the following symptoms or conditions, seek immediate medical attention:

• The person hits their head during fainting, with clear signs of head injury (e.g., bleeding).
• The person experiences double vision, difficulty speaking, numbness, or inability to move arms or legs.
• The person is unresponsive or unconscious.
• The person complains of chest pain (possibly clutching their chest) or has difficulty breathing.
• The person vomits red or coffee-ground-like material.

POTENTIAL DISEASES

What are the possible causes of fainting?

Fainting is primarily caused by a temporary insufficient blood supply to the brain. This condition may be related to impaired vasoconstriction or vasodilation, as well as heart diseases, brain disorders, or abnormal blood components^[1].
Common causes include the following (for reference only):

• Impaired vasoconstriction/vasodilation: Such as a rapid drop in blood pressure after changing body positions (e.g., from lying to sitting or standing); breath-holding during urination; or severe coughing due to lung diseases.
• Heart diseases: Such as arterial stenosis, sick sinus syndrome, Adams-Stokes syndrome, tachycardia, or atrial fibrillation.
• Brain disorders: Such as medulla oblongata lesions or fourth ventricle space-occupying lesions.
• Abnormal blood components: Such as severe anemia, hypoglycemia, severe dehydration, hyperventilation (excessively rapid breathing), or crying (common in children—crying followed by breath-holding, leading to cerebral hypoxia).