Hello, Thanks for posting your query in HCM The severity of head injury can be judged by the presence of accompanying symptoms. These symptoms are vomiting, loss of consciousness, convulsion, visual complaints, and weakness of legs and worsening of headache with posture. In the absence of these symptoms the chance of having a serious brain injury is highly unlikely; though cannot be excluded completely without through clinical and neurological assessment. As you said your son is getting his CT scan done today, it will help us know if here is any major problem or not. If CT head is normal, it is reasonably safe to fly. He may take simple analgesics for the control of headache. His treating doctor will guide him through tests and treatment Hope this helps