A hard blow to the head can cause a condition known as traumatic brain injury (TBI).
The U.S. National Institute of Neurological Disorders and Stroke mentions these possible symptoms of a TBI:
- Losing consciousness.
- Feeling confused, lethargic or tired.
- Developing a headache, or feeling lightheaded or dizzy.
- Having blurry vision or feeling that your eyes are tired.
- Hearing a false ringing sound in the ears.
- Having a bad taste in the mouth.
- Having changes in patterns of sleep, behavior, memory or concentration.