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What is it? Overview Usage Side Effects and Warnings

Electroencephalogram Overview

Written by FoundHealth.


The electroencephalogram (EEG) is a test that uses sensors to evaluate electrical brain activity.

Placement of Sensors for an EEG
Placement of Sensors for an EEG
© 2009 Nucleus Medical Media, Inc.

What to Expect

Prior to Test

Depending on the reason for your EEG, you may be given some of the following instructions:

  • Ask your doctor whether to stop any medicines, such as stimulants, prior to the test.
  • Avoid caffeine for eight hours before the test.
  • Shampoo your hair the day of the test. Do not use hairspray or gel that day.
  • If you are having a sleep-deprived EEG, you may need to stay awake the night before the test. You should also arrange for a ride to and from the test.
  • If you are prone to seizures, arrange for a ride to and from the test.

Description of Test

You will sit in a chair or lie on a cot. Electrodes will be attached to your scalp with special gel or paste. The electrodes will record the brain's electrical activity. You will be asked to close your eyes and be still for most of the test. You may be asked to breathe deeply and rapidly. A strobe light may also be used for a portion of the test. In some cases, the doctor will make a video recording of the test.

After Test

The technician will remove the electrodes, and you will be able to go home.

Talk to your doctor about restarting any medicines you may have stopped.

How Long Will It Take?

About one hour.

Will It Hurt?

No, an EEG is painless.


Your test results will be interpreted by a neurologist. Your doctor will receive a report within 1-2 weeks of your test. Discuss the results with your doctor.



Epilepsy Foundation

National Institutes of Health


Epilepsy Canada

Epilepsy Ontario


EEG (Electroencephalogram). KidsHealth website. Available at: . Updated September 2008. Accessed November 12, 2010.

EEG (electroencephalogram). Mayo Clinic website. Available at: . Updated May 2009. Accessed July 21, 2009.

Harrison TR, Fauci AS. Harrison's Principles of Internal Medicine. 14th ed. New York, NY: McGraw-Hill Company; 1998.

Shevell M, Ashwal S, Donley D, et al. Practice parameter: Evaluation of the child with global developmental delay: Report of the Quality Standards Subcommittee of the American Academy of Neurology and The Practice Committee of the Child Neurology Society. Neurology. 2003;60:367-380.



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