Fainting (syncope)

Fainting, also called syncope, happens when a person suddenly loses consciousness and then rapidly returns to normal. It is very common and can occur in up to 15% of adolescents.

Signs and symptoms of fainting

Right before fainting, your child might:

• feel dizzy or lightheaded
• feel weak
• see dark spots
• hear muffled sounds
• feel nauseous (want to vomit​)
• feel hot
• feel cold and clammy
• become pale
• start to sweat

Causes of fainting

Fainting can happen for a number of reasons. The most common cause of fainting is a temporary slowing of the heart rate and a drop in blood pressure. This type of fainting is called a “vagal” or “vasovagal” episode.

A child is more likely to have a drop in blood pressure if they:

• are dehydrated (from excessive sweating, diarrhea or vomiting)
• have not been eating
• have been standing still for a long time
• are unwell

Other common causes of fainting

A child might also faint if they

• are frightened
• are in severe pain
• stand up too fast

Fainting may be more likely in a closed setting or one that is hot and humid. It may also happen in response to a stimulus that is noxious (unpleasant or potentially harmful), such as a very bad smell or the sight of blood or a needle.

Conditions that appear similar to fainting

There are some conditions that look like fainting, but the loss of consciousness is actually caused by something else. These mimics of fainting include:

• an underlying heart condition or heart rhythm disturbance
• exposure to a medication, toxin or drug
• hypoglycemia (low blood sugar)
  
• anaphylaxis (allergic reaction)
• seizures
• migraine headaches​
• hyperventilation
• panic attacks
  

Fainting during exercise or exertion (carrying or pushing something heavy) can be a sign of an underlying condition and should be discussed with your child's health-care provider.

How to help your child if they have fainted

• Check to make sure your child is breathing. If necessary, call 911.
• Keep your child lying down or, if possible, sit them forward with their head between their knees.
• Loosen any tight clothing around your child's neck.
• Make an appointment with your child's health-care provider and explain exactly what happened.

When to see a health-care provider

See your child's health-care provider if:

• your child has had repeated fainting episodes
• fainting is accompanied by incontinence
• fainting occurs with exercise

Call 911 right away if your child:

• has stopped breathing
• does not quickly become alert or remains confused after fainting
• has changes in their speech, vision or ability to move

Your child may show physical changes when their condition is serious or when their condition gets worse. Parents and caregivers can learn how to spot these signs in order to seek help from a health-care provider.