Skip to Content

Computed Tomography Scan


A computed tomography (CT) scan

uses x-rays to take pictures of your blood vessels, tissues, bones, or organs. It is also called a computerized axial tomography (CAT) scan.

How to prepare for a CT scan:

Your healthcare provider will tell you which medicines to take or not take on the day of your CT scan. He or she may tell you not to eat or drink anything for 2 to 4 hours before your CT scan. Tell your provider if you know or think you are pregnant.

What will happen during a CT scan:

Your healthcare provider will ask you to lie on your back on a table. He or she may give you medicine to help you feel calm and relaxed. Contrast liquid may be used to help a body part show up better. The table will be moved into an open space in the middle of the machine. You will need to lie still during the CT scan.

Risks of a CT scan:

The contrast liquid may cause an allergic reaction. You may have a rash, itching, or trouble breathing. If you are pregnant, a CT scan may be harmful to your unborn baby. Contrast liquid may cause kidney problems that lead to kidney failure. The radiation from a CT scan may increase your risk for cancer.

Call your local emergency number (911 in the US) if:

  • You have any signs of an allergic reaction to the contrast liquid, such as trouble breathing, swelling of your mouth or face, or fainting.

Seek care immediately if:

  • You are dizzy or feel faint.
  • You have a rash, itching, or swollen skin.
  • You have nausea or are vomiting.
  • You are suddenly urinating less than usual.

Call your doctor if:

  • You have questions or concerns about your condition or care.

Drink liquids as directed:

Liquids will help flush the contrast liquid out of your body. Ask how much liquid to drink after your CT scan, and which liquids to drink.

Follow up with your doctor as directed:

Write down your questions so you remember to ask them during your visits.

© Copyright IBM Corporation 2021 Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or IBM Watson Health

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.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.