Minor head trauma may result in transient disturbance in brain functions for few seconds; so you may experience dizziness, confusion, headache and nausea. Despite most cases of minor head trauma pass without complications, but it may cause damage later over time as we don't know exactly the effect of this trauma.  

Anyway, according to doctors' recommendations and medical guidelines, it's advised to see the doctor after minor head trauma if the patient develops one or more of the following warning signs: 

1. Recurrent vomiting. 

2. Loss of consciousness (for minutes). 

3. Persistent headache. 

4. Numbness or tingling in the extremities. 

5. Persistent blurring of vision or vision loss. 

6. Marked neck pain or stiffness of cervical spine. 

7. Deterioration of neurological functions. 

8. Defect in concentration and memory functions. 

9. Feeling lethargy. 

10. Photophobia. 

11. Noise intolerance.