Children's responses to medical trauma are often more related to their subjective experience of the medical event rather than its objective severity. Reactions vary in intensity and can be adaptive or may become disruptive to functioning. The majority of pediatric patients and their families are resilient and do well.

Many ill or injured children and their families (up to 80%) experience some traumatic stress reactions following a life-threatening illness, injury, or painful medical procedure. Between 20 - 30 % of parents and 15 - 25% of children and siblings experience persistent traumatic stress reactions that impair daily functioning and affect treatment adherence and recovery. When they persist, traumatic stress reactions can:

• Impair day-to-day functioning
• Affect adherence to medical treatment
• Impede optimal recovery

There are three main types of traumatic stress reactions:

• Re-experiencing. Re-experiencing means that the child keeps thinking a lot about the trauma, even when he does not want to. Some re-experiencing is normal and natural. Thinking a lot about what happened, especially at first, is part of how we help ourselves recover from a scary experience.Too much re-experiencing can be very distressing. A child might have nightmares or “flashbacks” that make her feel like she is going through the trauma all over again. She may feel really upset or even have physical symptoms when something – a sight, a sound, a smell – reminds her of what happened.     
• Avoidance. Avoidance symptoms can start by trying not to think or talk about the trauma, or anything connected with it. Sometimes kids want to stay away from people, places or activities because these reminders upset them. And children sometimes develop new fears or worries. Of course, it can be good common sense to be more cautious after an injury. Children may become more aware of safety - remembering to wear a seat belt, not running into the street after a ball, or staying away from dogs they do not know. But extreme avoidance or fears can become a real problem. Avoidance can interfere with daily life and stop a child from getting back to enjoying things that she usually likes to do.
• Hyper-arousal. Hyper-arousal also starts with a natural and normal response to danger, the “fight or flight response.” After an injury or accident, this “fight or flight” response might not turn off, even when the child is safe. After a scary situation like being injured, a child might have the feeling that something bad could happen again at any time, or he might jump at any loud noise. The physical feelings that go along with hyper-arousal (e.g., heart racing) can feel scary themselves.