What causes fainting?

Fainting, or syncope, is very common among children and particularly among teenagers. The most common cause is the "common faint" (vasovagal syncope), which is related to low blood pressure, and can be triggered by many causes including:

  • Standing up too quickly or prolonged standing
  • An upsetting, unpleasant or painful experience
  • A hot shower
  • Dehydration (not drinking enough fluids)
  • Urinating
  • Having the hair combed or brushed
  • Breath-holding spells are a special case of fainting that occurs in infants or small children after a painful or frustrating experience and follows a very vigorous scream (or "silent scream" if no sound comes out).

Other causes of fainting include low blood sugar, migraines, overexertion, hyperventilation, abnormal heart rhythms, some types of heart problems and a variety of other conditions.

When shuold my child see a doctor about their experience with fainting?

Only a small percentage of young people with fainting turn out to have a serious problem, but warning signs that should prompt immediate evaluation by a physician include fainting associated with:

  • Exercise (fainting with exercise should prompt evaluation by a cardiologist)
  • No clear trigger or warning
  • Triggered by a surprise (such as a loud or sudden noise)
  • Congenital deafness (deafness since birth)
  • Difficulty breathing
  • Fever
  • Palpitations (the sensation of a fast or irregular heartbeat)
  • Chest pain
  • Known heart problems or a history of heart surgery
  • A family history of heart disease or sudden death
  • A history of drug abuse
  • The use of certain medications, including tricyclic antidepressants and some others

How do doctors treat children who experience fainting?

The most effective treatment of the "common faint" involves two components: 1) recognize the symptoms that come before a faint (dizziness, seeing spots, sweatiness) and lie down right away to prevent a faint; and 2) increase the amount of fluid intake to 6-8 glasses per day (2 liters) for an adult-sized person, especially during hot weather or in the setting of vigorous exercise. These two measures should, in most cases, prevent a faint from occurring. If fainting continues, or if any of the factors in the second list above occur, it is important to have a medical evaluation.

Who can I contact if I have questions?

Please don’t hesitate to contact Pediatric Cardiology at MassGeneral Hospital for Children at 888-644-3248 if you have any additional questions about your child’s heart.

Rev. 8/2018. MassGeneral Hospital for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.