Which of the following can be a sign of a head, neck, or spinal injury?

Nausea or vomiting can indeed be a sign of a head, neck, or spinal injury. These symptoms may indicate increased pressure within the skull, which can occur due to a concussion, traumatic brain injury, or other serious conditions affecting the brain or spinal cord. When there is a disruption in normal brain function due to injury, it can lead to various physical responses, including gastrointestinal upset, which commonly manifests as nausea or vomiting.

In contrast, flu-like symptoms, headache alone, and redness around the head do not specifically indicate a head, neck, or spinal injury. Flu-like symptoms can result from various infections unrelated to physical trauma, while a headache might also arise from many non-traumatic causes, such as tension or dehydration. Redness around the head might suggest an external injury but does not provide sufficient information to determine the possibility of internal injuries to the head, neck, or spine. Hence, nausea or vomiting stands out as a more significant indicator of potential serious injury in these areas.