Concussion: Symptoms & Signs

Medically Reviewed on 9/10/2019

A concussion is a form of minor brain trauma in which the function of the brain becomes altered but no abnormalities can be detected by imaging tests such as CT scans. Symptoms of a concussion are typically short-lived and go away on their own. The symptoms may be obvious or may be so subtle that the affected person does not realize they have suffered a concussion. Some of the more common symptoms of concussion include

  • headache,
  • feeling foggy, or that one's thinking is slowed or altered,
  • nausea,
  • lightheadedness,
  • dizziness,
  • irritability or emotional changes,
  • problems concentrating or remembering new information.

Sometimes people with a concussion will lose consciousness (pass out), but this does not happen in most cases. Not all symptoms of concussion will occur in every case; sometimes the symptoms differ depending on the location and extent of the injury. For example, some people suffering from a concussion may sleep excessively while others have insomnia. Symptoms of concussion can last for days, weeks, or occasionally even longer.

Concussion causes

Concussion is caused by a traumatic injury to the head. Concussion injuries are particularly common in those (including children and teens) who participate in athletic events.

Other concussion symptoms and signs


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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.

United States. Centers for Disease Control and Prevention. "Facts About Concussion and Brain Injury." <>.