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Symptoms and Signs of Concussion

Doctor's Notes on Concussion

Concussion describes a mild traumatic brain injury that causes functional changes in brain function but does not lead to structural damage to the brain. The loss of function is short-lived and goes away on its own. Trauma to the head from any cause, such as an accident or sports injury, is the cause of a concussion.

Symptoms of a concussion may be severe or very subtle and hard to describe, even by the affected person. These can include headache, loss of consciousness, mild confusion, nausea, dizziness, irritability, slowing of reaction times, and difficult concentrating or feeling that one’s thoughts are “foggy.” Other associated symptoms and signs can include changes in sleep pattern (either being unable to sleep or excessive sleep), and reduced tolerance of bright lights or loud sounds.

Medical Author:
Medically Reviewed on 3/11/2019

Concussion Symptoms

Common signs and symptoms of concussion are:

  • Loss of consciousness after any trauma to the head
  • Confusion
  • Headache
  • Nausea or vomiting
  • Blurred vision
  • Loss of short-term memory (you may not remember the actual injury and the events some time before or after the impact)
  • Perseverating (repeating the same thing over and over, despite being told the answer each time, for example, "Was I in an accident?")

Concussion Causes

A concussion can be caused by any significant blunt force trauma to the head such as:

  • a fall,
  • a car accident,
  • sports injury, or
  • being struck on the head with an object.

Concussions & Brain Injuries Symptoms, Tests, Treatment Slideshow

Concussions & Brain Injuries Symptoms, Tests, Treatment Slideshow

Although the brain is protected by tough bone (skull) and padding (membranes), it can still be injured. Head injuries that are severe enough to affect brain function are termed traumatic brain injuries (TBIs). Damage can range from mild to severe as the brain can affect everything you do.


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