Scan preparation
Smoking, Alcohol and Caffeine — Before a PET-CT Scan
Smoking, chewing tobacco, alcohol and caffeine all change how the radiotracer spreads through your body. If they are not stopped in time, the scan may show false results or miss something real — and it may need to be repeated.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed September 2026
- All four substances matter — Smoking, chewing tobacco, caffeine and alcohol each affect the scan differently. Stopping one but not the others is not enough.
- Gutka and khaini count — Chewing tobacco contains nicotine and often added sugar. Both distort how the tracer is absorbed — the same as cigarettes.
- Tell your team everything — If you have had any of these closer to the scan than instructed, say so at check-in before the injection is given.
- Your centre confirms the timing — Preparation instructions vary slightly by scanner and protocol. Confirm the exact timing with your centre when you book.
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Smoking, chewing tobacco, caffeine and alcohol all change where the radiotracer goes in your body and how brightly it shows on a PET-CT. This can create false bright spots or hide real ones. EANM and SNMMI guidance requires you to avoid all of them before your scan. Your booking team will tell you exactly how early to stop each one.
CION's PET-CT scans in Hyderabad start at Rs 10,499 — among the lowest published prices in the city, with no hidden charges. Indicative price, as of September 2026.
How long before a PET-CT scan should you stop smoking, caffeine and alcohol?
| Substance | Why it affects the scan | When to stop — confirm at booking |
|---|---|---|
| Cigarettes and bidis | Nicotine causes muscles to absorb the tracer, creating false bright areas that can look like tumour activity. | Most centres ask you to stop the morning of your scan at minimum. Some ask for longer. Confirm when you book. |
| Gutka, khaini, paan masala | Contains nicotine and often added sugar. Nicotine causes muscle uptake. Sugar raises blood glucose and changes tracer distribution across the whole body. | Stop at the same time as cigarettes. Always tell your team you use it, even if you have already stopped. |
| Alcohol | Alters how the body handles glucose, which is closely linked to how the radiotracer works. | Stop the day before your scan at minimum. |
| Tea, coffee, energy drinks, cola | Caffeine affects tracer distribution. The effect is most significant in heart scans, where caffeine can block the medication used to stress the heart. | Stop the day before your scan unless your team tells you otherwise. |
| Nicotine patches and nicotine gum | Still delivers nicotine to muscles. The scanner cannot tell this apart from a cigarette. The same effect on uptake applies. | Do not use on the day of your scan without asking your team first. |
Does gutka or khaini affect a PET-CT the same way cigarettes do?
Yes. Gutka, khaini, paan masala and other chewing tobacco products all contain nicotine. Nicotine affects the scan in exactly the same way regardless of how it enters the body.
Many of these products also contain sugar or sweeteners. A raised blood glucose level at the time of the scan changes how the tracer is absorbed across the whole body, not just in one area.
There is no need to feel embarrassed about telling your team you use any of these. They need to know so they can read the images correctly — and so they can advise you on when to stop before your appointment.
If you use these products daily and are worried that stopping suddenly before the scan is not safe for you, say so when you book. Your team will advise.
PET-CT Partner Centres
PET-CT Scan Centres in Hyderabad
CION offers PET-CT scans through 4 trusted partner PET-CT centres across Hyderabad, so you can choose the one closest to you. Call 18002028726 and we’ll guide you to the earliest available appointment.
PET-CT Centre — Punjagutta
PET-CT Centre — Himayatnagar
PET-CT Centre — Narayanaguda
These are partner diagnostic centres within the CION network. Toll-free booking: 18002028726.
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What do you need to do before your PET-CT scan?
Get your preparation instructions in writing when you book
Ask the centre to confirm the fasting time, what you can drink, and exactly when to stop smoking, tobacco, alcohol and caffeine for your specific scan. Keep the instructions with you.
Stop alcohol the day before your scan
This is the minimum. Do not assume a small amount is acceptable — alcohol alters glucose metabolism and will distort the result.
Stop caffeine the day before
This includes tea, coffee, energy drinks and cola. If you take caffeine in any other form, tell your team when you book.
Stop all tobacco products as instructed — the morning of the scan at minimum
This includes cigarettes, bidis, gutka, khaini, paan masala, nicotine patches and nicotine gum. Ask your centre whether they need you to stop the night before.
Fast from food as instructed, and drink plain water freely
Most PET-CT protocols require you to fast from food for several hours before the scan. Plain water is encouraged and helps flush the tracer through. If you have diabetes, speak to your care team before the scan — standard fasting instructions may not apply to you.
Tell the team at check-in about anything you have had
If you smoked, had a coffee or ate something accidentally, say so before the injection. The team can then decide whether to proceed or reschedule, and the radiologist will note it when reading the images.
Did you know?
On FDG PET-CT, nicotine causes increased uptake in the neck and shoulder muscles. This can appear as bright spots in areas where lymph nodes sit.
The pattern is distinguishable — but only when the radiologist knows you use tobacco. Declaring gutka, khaini or bidis at check-in protects the accuracy of your scan in exactly the same way as declaring cigarettes.
Source: EANM Procedure Guidelines for Tumour Imaging with FDG PET/CT
A whole-body PET-CT at CION is Rs 10,499 — among the lowest published prices in Hyderabad — with a free Rs 950 oncologist consultation to talk through your report. Indicative price, as of September 2026.
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Scan Day: What Actually Happens
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Common questions
Frequently asked questions
I accidentally had a cup of tea this morning. Will my scan still go ahead?
Tell the team at check-in before anything else — before the injection is given. They will ask when you had it, how much, and whether you have eaten. In some cases the scan can go ahead and the radiologist notes the deviation. In others it is safer to reschedule so the result is reliable. The worst outcome is saying nothing and having a result that is quietly misleading. Do not wait until after the injection to mention it.
Can I smoke as soon as the scan is over?
Yes. The restriction applies before and during the scan only. Once the scan is complete and the team confirms nothing more is needed, you can resume. If you would like to use the preparation period as a starting point to cut down or stop, tell your oncologist — they can point you toward support.
I use gutka every day. Is it safe to stop suddenly before the scan?
For most people, stopping gutka for one day before a scan does not cause a medical problem. If you are concerned because you use it very heavily, or because you have other health conditions, say so when you book. Your team will advise on what is safe. Do not avoid telling them because you think they will judge you — they need the information to read your scan accurately, and this comes up regularly.
I use a nicotine patch to help me stop smoking. Do I have to remove it before the scan?
Yes, for the day of the scan. Nicotine patches deliver nicotine continuously, and the scanner cannot tell this apart from cigarette use. The same muscle uptake effect applies. Tell your team when you book that you use a patch, and they will advise exactly when to remove it before your appointment.
Does it matter whether I am having a heart scan or a cancer scan?
Both are affected, but in slightly different ways. Caffeine restriction is especially important for cardiac PET-CT, because caffeine blocks the medication used to stress the heart during the test. For oncology FDG scans, the main concerns are blood glucose and nicotine affecting tracer distribution. Your booking team will give you protocol-specific instructions. Always follow those over any general guidance you read online.