The American Academy of Family Physicians lists the following warning signs of concussion, which should be evaluated as soon as possible by a doctor:

• Headache.
  
  
• Difficulty seeing.
  
  
• Dizziness.
  
  
• Difficulty concentrating, memory loss or confusion.
  
  
• Problems retaining balance.
  
  
• Nausea.
  
  
• Ringing in the ears.