Why do children faint?

Fainting, also known as syncope, occurs when there is a sudden drop in blood pressure, or heart rate, that results in brief loss of consciousness. It is more common than many realize, affecting up to 30% of children, particularly adolescents. It is more than twice as common in females than in males.

Fainting can be scary for parents to witness, but most of the time it is not a cause for concern. However, there are some situations when you would want to discuss fainting with your child's doctor. Parents should be aware of why fainting happens and what to look out for.

What causes fainting?

Most of us don't think about our autonomic nervous system, which controls our heart rate and blood pressure in response to sensors all over the body. As children and adolescents grow, this system is still developing and sometimes overreacts – causing them to faint when their blood pressure or heart rate suddenly drops.

Fainting in teens can occur in common situations, such as after they step out of a hot shower. They may feel sick or dizzy, and it is common for them to appear pale and sweaty before they faint.

Some reasons that might cause fainting include:

• Situational triggers, such as prolonged standing in hot or crowded environments. These events are more likely with dehydration.

• Physical triggers, such as seeing needles or receiving a shot. Another common trigger is hair brushing.

• Emotional stress, such as fear or anxiety

• Hyperventilation

• Low blood sugar

It is unusual for children to faint before the age of 6 unless they have seizure disorders, heart conditions or have been holding their breath.

Fainting and sports

While fainting after exercise is usually not concerning. However, fainting during exercise — such as while running or playing sports — is more concerning and should be evaluated by a doctor,  as it can signal an underlying heart condition. Other warning signs include unusually fast or irregular heart rates.

Sudden cardiac arrest in children is rare. But it's important to know your family's medical history and discuss it with your child's doctor because symptoms of heart conditions may not show up until children get older and start to participate in competitive sports. If you have a relative who died suddenly at a young age, that is something to discuss with your pediatrician before your child plays sports. In some cases, a pediatrician may recommend further evaluation by a cardiologist.

Some organizations offer heart screening tests, such as electrocardiograms or echocardiograms, for young athletes. These tests are not recommended for every child and cannot detect all heart conditions, but they may be considered in certain situations or for families seeking additional reassurance.

In addition to fainting, parents should tell their child’s doctor if a young athlete experiences chest pain during physical activity, unusual shortness of breath, or becomes tired more easily than before.

What to do if your child faints

If your child faints, check to see if he or she is breathing OK. Position the child on their back and look for any injuries. If the child doesn't recover fully in a few minutes, take him or her to the emergency room.

In the very rare circumstance the child is unresponsive, begin CPR and call 9-1-1. Every parent should know CPR and know that an AED (portable defibrillator) is available wherever children participate in sports.

If your child faints outside of exercise and does not appear to have any physical injuries, it may not be as urgent. Call your child's doctor to assess the urgency of the situation. Full recovery usually occurs within a minute, but the child may feel tired the rest of the day. For most children who faint, a detailed account of the event is very informative, and no tests are needed.

Learn more

The nationally renowned team of pediatric cardiologists and subspecialists at Children's Health treat the whole spectrum of pediatric heart problems, with a commitment to excellence. Learn more about our programs and treatments.