Which symptom would raise concern for a life-threatening cause of headaches in children?

The symptom that raises significant concern for a life-threatening cause of headaches in children is a headache that awakens one from sleep. This particular symptom can indicate increased intracranial pressure or other serious conditions such as a brain tumor or a serious vascular event. Headaches that disrupt sleep are often more alarming because they can suggest something critical occurring within the central nervous system, warranting immediate medical evaluation.

In children, normal headaches are usually linked to common etiologies such as tension or migraine, which typically do not lead to awakening from sleep. Symptoms that occur at night and interfere with a child's ability to rest are out of the ordinary and may point to deeper underlying issues that require urgent assessment to rule out potentially drastic health concerns.