by EBSCO Medical Review Board
(Anoxic Brain Injury; Hypoxic Brain Injury)


Anoxic brain damage (ABD) is harm to the brain due to a lack of oxygen. Brain cells without enough oxygen will start to die after about 4 minutes.

Progression of Anoxic Brain Damage
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Oxygen is carried to the brain in the blood. ABD is when:

  • Blood flow is blocked or slowed due to:
  • Blood flow is normal, but the blood doesn’t have enough oxygen due to:
    • Lung disease
    • A lack of oxygen in the air, which may happen at high altitudes
    • Being around certain poisons, such as carbon monoxide
    • An event that is stopping breathing, such as drowning, choking, or suffocation

Risk Factors

Problems that may raise the risk of ABD are:


Problems may be:

  • Headache
  • Problems with thinking and focus
  • Mood swings
  • Loss of consciousness
  • Seizures
  • Clumsiness
  • Coma
  • A decline in brain function days or weeks after the event (rare)


You will be asked about your symptoms and health history. A physical exam will be done. You may need to see a doctor who treats brain problems.

These tests may be done to find out more about problems with brain function:

  • CT scan
  • MRI scan
  • Electroencephalogram (EEG)—a test that measures the electricity in the brain
  • Single-photon emission computed tomography (SPECT) scans—a type of CT scan that looks at parts of the brain
  • Evoked potential tests—tests used to check the senses


Initial Treatment

Treatment will depend on the cause. Choices are:

  • Oxygen to raise the amount of oxygen in the blood
  • Medicine to help get enough blood with oxygen to the brain
  • Cooling the brain to limit problems


Recovery can take months or years. It depends on how long a person went without oxygen. Many people can get back most of the abilities they lost.

These therapies may be needed:

  • Physical therapy to retrain motor skills, such as walking
  • Occupational therapy to relearn daily skills, such as dressing and going to the bathroom
  • Speech therapy to work on language problems
  • Counseling for behavior and emotional issues


ABD is often caused by accidents. These cannot always be prevented.


Brain Injury Association of America 

National Institute of Neurological Disorders and Stroke 


Ontario Brain Injury Association 

Public Health Agency of Canada 


Cerebral hypoxia information page. National Institute of Neurologic Disorders and Stroke website. Available at: Accessed June 18, 2018.

Rubinos C, Ruland S. Neurologic complications in the intensive care unit. Curr Neurol Neurosci Rep. 2016;16(6):57.

Revision Information

  • Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
  • Review Date: 09/2020
  • Update Date: 05/21/2021