Side Effects of a — PET-CT Scan

There is a small radiation dose from both the radiotracer and the CT component. Regulatory bodies including the IAEA and WHO consider this level acceptable for diagnostic use, and your oncologist requested the scan because the information it provides is expected to outweigh that risk for you specifically. If you are pregnant, trying to conceive, or breastfeeding, tell your team before any scan — the calculation is different in those situations.

Most people feel nothing at all. A small number notice mild nausea, a brief warm sensation, or light-headedness at the time of injection, and these settle within a minute or two. If you feel unwell at any point during your appointment, tell the radiographer immediately rather than waiting.

Yes, with simple precautions for the rest of the day. Avoid prolonged close contact with pregnant women and children under five, and use your own bathroom rather than sharing with them. Normal social contact — talking, sitting at a table, hugging older children and adults — is fine immediately. By the following morning there are no special precautions needed.

In most cases, yes. The scan itself does not affect your ability to drive. If you were given a sedative or anti-anxiety medicine before the scan, you should not drive — your team will have advised this before the appointment. If you are unsure, ask at the scanning centre before you leave.

A rash, swelling, difficulty breathing, chest tightness, or any symptom that is getting worse rather than better is a reason to call the scanning centre immediately or go to the nearest emergency department. Do not wait until your next oncology appointment.

Mild soreness or a small bruise at the cannula site is normal and usually settles within a day or two without treatment. If the area becomes significantly swollen, warm, red, and is getting worse after 48 hours, or if you develop a fever alongside it, contact your treatment team.

The radiotracer is designed to clear quickly. Most of it leaves through your urine within a few hours of the scan, and drinking water helps this along. By the following day the level remaining in your body is very low. The specific tracer your team used determines the exact timeline — you can ask at the scanning centre.

No. The radiotracer does not interfere with chemotherapy, immunotherapy, or other treatment you are having. Your oncologist will tell you how long to wait before the scan results are formally reviewed, and how those results will shape decisions about your treatment plan going forward.