CT Scans for Headache and Migraine Diagnosis

Medically Reviewed by Arefa Cassoobhoy, MD, MPH on March 28, 2023
3 min read

A CT scan uses X-rays and computers to make images of the body. It can sometimes help doctors diagnose headaches and their causes.

You might need one if you have headaches daily or almost every day or have a sudden onset severe headache. Doctors can’t diagnose migraines with the test, though.

The test can help your doctor rule out other causes of your pain, such as:

The test is painless. To get the scan, you'll lie on a table. You may get a shot of "contrast material" into one of your veins, which will help doctors see parts of your brain more clearly on the image.

Be sure to tell the doctor or nurse if you've had an allergic reaction to contrast material in the past. Your doctor will also need to check your kidney function before using contrast. The dyes have iodine, which can cause a reaction in some people.

The CT scanner uses X-rays, but the amount of radiation you get from them is kept to a minimum. But if you are or think you may be pregnant, let the doctor know -- X-rays can be harmful to a growing baby. A child who needs to have a CT scan should get it at a facility that often works with children, so that the lowest possible dose of radiation can be used.

  • Don’t eat anything 4 hours before your CT with contrast.
  • Keep taking your medications as usual after you check with your doctor.
  • Plan for your test to take at least an hour. Most scans take from 15 to 60 minutes.
  • Ask your doctor any questions you have before the scan.
  • You may get a drug that will make you feel relaxed and drowsy.
  • You may need to change into a hospital gown, because snaps and zippers in street clothes can interfere with the scan. You also may need to take off your watch, rings, or jewelry. It's a good idea to leave your valuables, including jewelry, at home.
  • If you get a shot of contrast material, you may feel flushed, or you may have a metallic taste in your mouth. These are common reactions. If you have shortness of breath or any unusual symptoms, tell the person who's giving you the test -- the technologist.
  • The technologist will help you lie in the correct position on the examining table. The table will then automatically move into place for imaging. It’s very important that you lie as still as possible during the procedure. Movement could blur the images.
  • The technicians may ask you to hold your breath briefly at some points when they're taking the X-ray images.

You can go back to your usual activities and eating habits right after a CT scan.