Electroencephalogram

Medically reviewed by Drugs.com. Last updated on Mar 10, 2025.

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What do I need to know about an electroencephalogram (EEG)?

An EEG is a test that measures the electrical activity in your brain. It can help healthcare providers decide what treatments you need. An EEG can also help diagnose or monitor any of the following:

• Seizures
• Sleep disorders
• Brain infection, disease, or injury
• Brain activity during brain surgery or a coma

Drugs used to treat this and similar conditions

How do I prepare for an EEG?

Your healthcare provider will talk to you about how to prepare for an EEG. The provider will tell you which medicines to take or not take on the day of your test. Do not drink or eat foods with caffeine on the day of your test. Do not put oils or lotions on your scalp or hair for 24 hours before your test. This includes conditioner, hair spray, hair cream, or hair gel. Your provider may tell you to sleep less than usual the night before your test.

What will happen during an EEG?

• You will not feel pain during the test. Healthcare providers will ask you to lie still, and not talk during the test. A provider will put gel or cream on your scalp. Small discs will be placed in different places on your head. The discs will be connected to wires and a monitor. The monitor will show healthcare providers your brain's electrical activity.
• During the test you may be asked to change how fast you breathe. You may also be asked to look at pictures or a flashing light. You may also hear loud noises.
• Bright lights or loud noises may cause you to have a seizure during the test. Healthcare providers may give you medicine to control or stop your seizure. They will also protect you from injury.
• You may be given medicine to help you sleep during the test. You may also be videotaped during the test. The videotape will help providers look for signs of a seizure.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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