Vasovagal Syncope: This is the most common cause of syncope in children and adolescents, often triggered by stress, pain, or prolonged standing. It is characterized by a sudden loss of consciousness due to a temporary decrease in blood flow to the brain.

Dehydration: Dehydration can lead to a decrease in blood volume, reducing blood flow to the brain and causing syncope. This is particularly common in children who may not drink enough fluids or have increased fluid loss due to vomiting or diarrhea.
Anxiety or Panic Attacks: Anxiety and panic attacks can cause symptoms that mimic syncope, including dizziness and fainting, especially in adolescents.
Orthostatic Hypotension: This condition is characterized by a significant drop in blood pressure when standing up, which can lead to syncope. It can be due to various factors, including dehydration, medication, or autonomic nervous system dysfunction.

Cardiac Conditions (e.g., Hypertrophic Cardiomyopathy, Long QT Syndrome): Although less common, cardiac conditions can cause syncope and are potentially life-threatening if not diagnosed and treated promptly.
Neurological Conditions (e.g., Seizures, Migraines): Certain neurological conditions can present with symptoms of syncope, and missing these diagnoses could lead to inappropriate treatment and potential harm.
Subarachnoid Hemorrhage: Although rare in children, a subarachnoid hemorrhage is a medical emergency that can present with sudden loss of consciousness and must be ruled out.

Pulmonary Embolism: Extremely rare in children but can occur, especially with underlying conditions such as thrombophilia or after significant trauma.
Endocrine Disorders (e.g., Hypoglycemia, Adrenal Insufficiency): Certain endocrine disorders can lead to syncope due to metabolic imbalances or hormonal deficiencies.
Infectious Diseases (e.g., Meningitis, Encephalitis): Infections affecting the central nervous system can cause a range of symptoms, including syncope, and require prompt diagnosis and treatment.