The signs and symptoms of a concussion can be subtle and may not be immediately apparent. Symptoms can last for days, weeks or even longer.

Common symptoms after a concussive traumatic brain injury are headache, loss of memory (amnesia) and confusion. The amnesia, which may or may not follow a loss of consciousness, usually involves the loss of memory of the event that caused the concussion.

Signs and symptoms of a concussion may include:

• Headache or a feeling of pressure in the head
• Temporary loss of consciousness
  
• Confusion or feeling as if in a fog
  
• Amnesia surrounding the traumatic event
  
• Dizziness or "seeing stars"
  
• Ringing in the ears
  
• Nausea
  
• Vomiting
  
• Slurred speech
  
• Delayed response to questions
  
• Appearing dazed
  
• Fatigue
  

Some symptoms of concussions may be immediate or delayed in onset by hours or days after injury, such as:

• Concentration and memory complaints
  
• Irritability and other personality changes
  
• Sensitivity to light and noise
  
• Sleep disturbances
  
• Psychological adjustment problems and depression
  
• Disorders of taste and smell
  

Symptoms in children

Head trauma is very common in young children. But concussions can be difficult to recognize in infants and toddlers because they may not be able to describe how they feel. Nonverbal clues of a concussion may include:

• Appearing dazed
  
• Listlessness and tiring easily
  
• Irritability and crankiness
  
• Loss of balance and unsteady walking
  
• Crying excessively
  
• Change in eating or sleeping patterns
  
• Lack of interest in favorite toys
  

Other symptoms include:

• Seizures
  
• Vision or eye disturbances, such as pupils that are bigger than normal (dilated pupils) or pupils of unequal sizes
  
• Lasting or recurrent dizziness
  
• Obvious difficulty with mental function or physical coordination
  
• Symptoms that worsen over time
  
• Large head bumps or bruises on areas other than the forehead in children, especially in infants under 12 months of age