A Clear Liquid Diet Before a CT Scan

A computerized tomography, or CT, scan is a diagnostic testing procedure that involves taking X-rays to create cross-sectional images of an area of the body. For many CT scans, a contrast material, or dye, is swallowed or injected to emphasize certain structures on the X-rays. When CT scans are used to diagnose stomach or intestinal diseases, your doctor may recommend a clear liquid diet prior to the CT scan so the contrast is more visible and the CT picture is clear.

A technician standing next to a CT scan machine. Credit: nimon_t/iStock/Getty Images

Diet Basics

Clear liquids are easily digested and leave minimal residue in the digestive tract. Because of this, they are often prescribed for diagnostic testing, such as CT scans, which require an empty digestive tract. According to the University of California San Diego Health System, you generally need to follow a clear liquid diet for about four hours prior to a CT scan. You should be able to take medications as usual, with the exception of certain diabetic medications.

What to Consume

While on a clear liquid diet, you can generally have anything that you can see through. Drink apple juice, grape juice, plain tea, black coffee, water, soda water, ginger ale and lemon-lime soda. You can also consume plain ice pops and any gelatin that does not contain fruit. To incorporate a little variety, add spices to plain broth to replace a lunch or breakfast meal. Although beer, white wine and some spirits are clear, alcohol is not permitted on a clear liquid diet.


In most cases, you can resume your normal diet directly after the CT scan. The University of California San Diego Health System notes that you should drink at least five to six 8-ounce glasses of water per day for at least two days following the CT scan. This helps flush out your system, removing media used during the procedure.


While a clear liquid diet keeps you hydrated, it does not provide you with the vitamins, minerals and nutrients you need to stay healthy for the long term. Because of this, you should only follow a clear liquid diet for the recommended amount of time. The Maine Medical Center notes that you may need a nutritional supplement if required to follow a clear liquid diet for more than three days prior to a CT scan -- this may be the case if you're gearing up for an intestinal surgery. Work closely with your doctor or dietitian to determine the proper diet plan. It is important to precisely follow a clear liquid diet before a medical procedure, such as a CT scan. Cheating can lead to inaccurate readings and the need to reschedule the procedure.

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