What happens if you eat before a CT scan?

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What happens if you eat before a CT scan?

Cancer, they say!

Eating before a CT scan can increase your risk of having cancerous growth beneath the skin, especially when you have a CT scan with contrast dye. At that time, you are not allowed to eat anything solid before a CT scan nearly for three to six hours! However, you are encouraged to drink clear liquids before a CT scan; not those sugary drinks, beware!

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How does eating before a CT Scan increase the risk of cancer? – You must be wondering!


It is a myth!


The American Cancer Society recommends you not eat for at least two hours before a CT scan.

But it has got nothing to do with eating before a CT scan, to be honest! The risk of cancer comes from the process of a CT scan, and eating can make you feel like vomiting due to the effect of contrast dye if any, but nothing otherwise!

The amount of radiation you receive in a CT scan is, indeed, higher than that of any other imaging test like an X-Ray scan or Mammogram. But, the amount is still less to stimulate cancer on one stroke! Today, the rate of cancer detected after a CT scan is only 1 out of 2000!


Hence, a CT scan is yet worthy to be pursued for an early diagnosis of what’s bothering you from inside, structurally or functionally, despite such radiation risk!

Yet again,

Although the chances of getting cancer through a CT scan are quite low, you cannot eradicate its possibility!

The process of CT scan or Computed Tomography involves X-rays or ionizing radiation; that when transgressed in dose, can encourage & help cancerous growth. Do you know how? They do it by damaging the DNA in your cells and reducing the immunity to resist abnormal cell growth. You never know what may go wrong!

So, what is the best way is only what the doctor asks you to follow. Refer to her!

Why do medical experts say you need to fast for two hours before a CT scan?

Perhaps, this is the question worth answering at this stage! Eating before a CT scan has a setback;  it is not a medical condition that may arise out of the blue but it may turn out to be harmful to the body if the test is contrast-enhanced.

Why so?

It is because the reaction of the contrast dye in interaction with food particles inside your body can culminate sensation of vomiting or nausea. Sometimes, you can also witness dizziness & fatigue, or abdominal pain, as post-CT side effects!

Dr. Yoshito Tsushima, Gunma University, Department of Diagnostic Radiology & Nuclear Medicine, states, “Instructions to fast for several hours before administration of contrast media were considered essential and this policy has traditionally been kept due to concerns about vomiting and its potential to cause aspiration…”

Other allergic reactions may emerge after a CT scan if you intake solid food before the test. However, over-fasting is simultaneously discouraged. You would have to eat a healthy meal the day before your CT scan.

4 Ways to avoid eating before a CT Scan – See-through!

  • You have to avoid eating solid foods, you know. But consider the loophole and intake as many clear fluids as you want. Maybe some green tea?
  • If you are too hungry & you know there are more than 6 hours in hand before the CT scan appointment, try some healthy snacks. Avoid a large meal! Your healthy snacks can be some dark chocolate, what say?
  • Stay away from alcohol or caffeine and compensate for that with a green smoothie! Trust me; it does not taste bad!
  • Have a large meal on the day before the CT scan. This shall keep you standing until your test is complete.

What should you eat before a CT scan?


First & foremost,

You need to consult with your doctor about the timing. Some doctors suggest you stay on fast for six hours, some suggest 2-3 hours, and some suggest that you can eat even before an hour of your CT scan, but not a heavy one.

If you have a meal 24 hours before your CT scan, the diet must include –

  1. Enough proteins maybe like chicken or egg, fish, nuts & seeds, but no red meat, please! That is too many calories and can cause indigestion if you have a contrast-enhanced CT scan.
  2. Non-starchy vegetables, plenty of them; those broccolis, spinach, cauliflower, mushrooms, cucumber. You can have it as a salad dish or soup!
  3. Green tea or some zero-calorie drink.
  4. Ample amount of water to keep yourself hydrated!

What should you avoid eating before a CT scan?

There is a lot of food in your diet that you need to quit for a day, at least, before you pursue a CT scan, and they are as follows!

  1. Cereals & Rice,
  2. Dry Beans,
  3. Plates of pasta & Pizzas, Slices of bread,
  4. Corns & Peas,
  5. Potatoes,
  6. Jams, Syrups & Jellies,
  7. Ketchup,
  8. Cheese, Butter, & Ghee,
  9. Milk or Milk-based drinks,
  10. Processed Meat, those salamis & sausages, hams & bacon,
  11. Honey, Candy, Cakes, Pastries,
  12. Savories like Patis or Rolls,
  13. Fruit & Fruit juices,
  14. Mints,
  15. Chewing gums,
  16. Wine, Beer, & Alcohol.

Make sure to not include these in your meal before the CT scan else indigestion may become a big problem!

Concluding Remarks:

Are you satisfied with the answer to your question? Did you find the appropriate solution? If not, connect with us and share your doubts at Mrichandigarh.com.

If yes, make sure you still take approval about how to prepare for your CT scan and when to eat before a CT scan!

Signing off for today! Stay safe & pursue your CT scan safely!

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About author
Hi, I am Alka Tiwari, Founder & Patient Care Executive at MRIChandigarh.com. Helping you get the diagnostics scans services like MRI, CT Scan, UltraSound & PET Scan, etc at the best price. At MRIChandigarh's blog, I will be writing to create awareness and to educate you about how and where to get diagnostic scans done in Chandigarh at the best price with best-in-class services.
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Edward Houghton-Ward
Edward Houghton-Ward
1 year ago

Thanks, Alka, most informative. I liked the acknowledgment of the 1:2000 cancer risk, slight, and hard to pin down. Nevertheless, if one already has cancer would it not be wise to advise clients of the risks associated with additional radiation?

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