PET-CT emergencies
When a PET-CT Scan Reaction — Needs Emergency Care
Reactions to a PET-CT scan are rare, but a few are serious and need immediate care. Knowing which symptoms to act on — and what to do — can make a real difference.
Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed September 2026
- Reactions are rare but real — Most people have no reaction at all. A small number develop a response to the tracer or contrast agent.
- Breathing problems are an emergency — Throat tightening or difficulty breathing after a scan means go to hospital now, not a call-back tomorrow.
- Timing matters — Serious reactions usually start within minutes of the injection. If you feel unwell, say so before you leave the imaging centre.
- Tell them it was a PET-CT — The emergency team needs to know what was injected and when. Say so as soon as you arrive.
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Serious reactions to a PET-CT scan are rare, but they happen. Throat tightening, difficulty breathing, face or tongue swelling, or collapse after the tracer injection are emergencies — go to hospital immediately. A spreading rash, faintness, or severe pain at the injection site needs same-day review, not a wait-and-see approach.
If a symptom below applies to you, do not wait for a callback. Call 1800-202-8726 or go to your nearest emergency department.
Is this a mild reaction or something serious?
| Symptom | Mild — call your scan team | Serious — go to hospital now |
|---|---|---|
| Typically starts | During or shortly after the injection | Minutes to an hour after the injection |
| Skin | Small patch of redness or hives that settles | Widespread hives, fast-spreading rash, or visible swelling |
| Breathing | Normal | Tight, noisy, wheezing, or laboured |
| Throat | Mild scratchy feeling | Tightening or a feeling of obstruction |
| Face or tongue | No swelling | Visible swelling of lips, face, or tongue |
| Consciousness | Fully alert | Faint, lightheaded, or collapsed |
| Injection site | Mild ache or small bruise | Severe pain, firm swelling, or discoloured skin |
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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Not sure whether this counts as an emergency?
Call the helpline. It is always better to check than to wait.
What do you tell the emergency team when you arrive?
Tell them you had a PET-CT scan, the name of the imaging centre, and the approximate time of your injection.
If you were also given an intravenous contrast agent, say so. It is a different substance from the radiotracer, and the team needs to know exactly what you received.
Bring any paperwork the imaging centre gave you. Your appointment letter or consent form will name the tracer and the contrast agent if one was used.
What should I take with me to the emergency department?
- Ask someone to drive you — do not drive yourself if you feel unwell.
- Take your appointment letter or scan consent form if it is within easy reach.
- Tell the triage nurse the time and location of your injection as soon as you arrive.
- Bring your allergy record or medical alert card if you have one.
- Let your oncology team at CION know you were seen in emergency, even if everything resolved quickly.
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.
Explore 62 more Family Support, Myths, Follow-Up and Emergencies topics
Emergencies & Red Flags
- Accidental Radiation Exposure: Pregnancy Discovered After a Scan
- Breathing Difficulty During or After a Scan
- Delayed Contrast Reaction Hours After the Scan
- Emergencies Around a PET-CT Scan: What Needs Immediate Care
- Fainting or Collapse at the Scan Centre
- Low Blood Sugar (Hypoglycaemia) During Fasting
- Panic Attack During the Scan
- Severe Contrast Reaction: Recognising It
- What to Do If the Cannula Site Swells or Hurts After
- When to Call the Centre After Your Scan
Caretaker & Family Guide
- A Printable PET-CT Day Checklist for Families
- After the Scan: What the Family Should Know
- Collecting and Storing the Report and Images
- Coordinating a Scan for a Parent in Another City
- Explaining a Parent's Scan to Children
- Explaining the Scan to an Anxious Patient
- Getting an Elderly Parent to and From the Scan
- Helping Someone Fast Before a PET-CT
- Managing Cost and Payment as a Family
- Preparing Questions for the Post-Scan Consultation
- The Family's Complete Guide to a PET-CT Scan Day
- What the Attendant Can and Cannot Do During the Scan
Follow-Up & Surveillance Scanning
- Can You Refuse a Follow-Up PET Scan?
- Follow-Up Scanning During Long-Term Treatment
- How Often Will You Need a PET-CT After Treatment?
- Is Routine Surveillance PET Actually Recommended?
- Keeping a Personal Scan Log
- Reducing Radiation Across Years of Surveillance
- Scan-Based vs Symptom-Based Follow-Up
- Surveillance Scanning by Cancer Type: A Reference Table
- The Annual Cost of Cancer Surveillance Scanning
- Transferring Surveillance to a Centre Closer to Home
- What Happens If a Surveillance Scan Shows Something?
- When Can You Stop Having Scans?
Myths & Misinformation
- Ayurvedic and Alternative Alternatives to a PET Scan
- Myth: A Normal PET Scan Means You Are Cured
- Myth: A PET Scan Can Cause Cancer
- Myth: A PET Scan Detects Every Cancer
- Myth: A PET Scan Spreads or Worsens Cancer
- Myth: A Positive PET Scan Means You Definitely Have Cancer
- Myth: A Scan From a Cheaper Centre Will Not Be Accepted
- Myth: An Expensive Scan Is Always a Better Scan
- Myth: Eating Sugar Before a Scan Will Show Up Cancer
- Myth: PET Scans Are Only for Terminal Cancer
- Myth: The Tracer Injection Is a Kind of Chemotherapy
- Myth: You Should Avoid Water After a PET Scan
- Myth: You Should Get a PET Scan Every Year to Be Safe
- Myth: You Stay Radioactive for Days After a PET Scan
Scanxiety & Emotional Impact
- Fear of What the Scan Will Find
- Getting Bad News From a Scan Report
- Getting Good News: Why Relief Is Complicated
- Living Between Scans: The Six-Month Rhythm
- Making the Most of Your Post-Scan Consultation
- Recurring Scanxiety in Long-Term Surveillance
- Scanxiety: The Fear Before and After a PET-CT
- Should You Look Up Your Results Online Before the Consult?
- Supporting Someone Through Scan Day
- Telling Family About Scan Results
- The Night Before a PET-CT Scan
- Waiting for PET-CT Results: How to Get Through It
- When a Patient Refuses to Have the Scan
- When to Seek Counselling Around Scans
Your next step
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Common questions
Frequently asked questions
Can the PET-CT tracer cause an allergic reaction?
Yes, though it is uncommon. The FDG radiotracer used in most PET-CT scans can, rarely, trigger a reaction ranging from mild skin redness to a serious response. If contrast dye is also used, that carries its own small additional risk. The ACR advises imaging centres to observe patients for a period after injection for this reason. Tell the scan team before your appointment if you have had any previous reaction to an injection or contrast agent — they can monitor you more closely.
How soon after the injection would a serious reaction appear?
Most serious reactions appear within the first hour after the tracer is injected, and many happen within minutes. This is why imaging centres ask you to remain nearby rather than leaving immediately. If you leave and develop throat tightening, difficulty breathing, or a spreading rash on the way home, go to the nearest emergency department rather than returning to the imaging centre.
Is the radiation from the PET-CT scan something to worry about in the days after?
No. The radiotracer decays quickly and is cleared from your body mainly through urine over a few hours. It does not cause symptoms in the days after the scan. If you feel unwell after your scan, it is far more likely to be related to your cancer treatment or another cause than to the scan itself. Tell your oncology team about any new symptoms so they can assess what is causing them.
What if I feel a bit unwell but I am not sure it is an emergency?
Call the imaging centre that did your scan first. If they are closed, call your CION oncology team. If you cannot reach either and you are worried, go to the nearest emergency department and explain that you had a PET-CT scan that day. Feeling unwell after any medical procedure is worth acting on promptly, even when you cannot name exactly what is wrong. If your symptoms are worsening rather than settling, go now.