Symptoms of a serious head injury may include:

• Passing out.
• Becoming more and more drowsy, or hard to wake up.
• Cannot stop crying.
• New eye problems, such as a difference in the size of the pupils of the eyes or a droopy eye or an eye that moves differently than before.
• Unsteady walking or decreased coordination.
• Slurred speech.
• Acting in a way not normal for them, such as acting confused, agitated, or restless.
• Not eating or nursing.
• Ongoing vomiting.

Note: It can be hard right after a head injury to tell the difference between a mild and a more serious injury. It's important to look for any changes in usual behavior or movements.