PET Scan Myths
The PET Scan Injection — Is Not Chemotherapy
Many people delay or refuse a PET scan because they believe the injection is a form of chemotherapy. It is not. Knowing what is actually in the injection removes that fear.
Medically reviewed by Dr. Bharati Devi Gorantla, Medical Oncologist, MBBS · MD · DM (Adyar, Chennai) · ECMO · MRCP SCE (UK) · Last reviewed September 2026
- Not a cancer drug — The injection is a radioactive tracer — a tiny amount of sugar tagged with a short-lived radioactive atom.
- Clears within hours — The radioactive element decays quickly. Most of it is gone before you leave the scanning centre.
- No cancer treatment — The tracer does not kill cells or affect your cancer. It only shows where cells are using energy.
- Side effects are rare and mild — Most people feel nothing. The tracer does not cause nausea, hair loss, or fatigue.
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The injection you receive before a PET scan is not chemotherapy. It is a radioactive tracer — a tiny amount of a sugar-like substance tagged with a short-lived radioactive atom. It shows how your cells use energy so the scanner can build a detailed picture. It does not treat cancer, and it clears from your body within hours.
PET-CT at CION starts from Rs 10,499 — among the lowest published prices in Hyderabad, with no hidden charges. Indicative price, as of September 2026.
Is the PET scan injection the same as chemotherapy?
The injection is a form of chemotherapy.
It is a radioactive tracer, not a cancer drug. Chemotherapy kills fast-dividing cells throughout the body. The tracer does none of that — it maps how cells use energy and leaves your body within hours.
I will feel sick after it, the way people do on chemo.
Most people feel nothing after the tracer injection. A very small number notice brief warmth or a metallic taste for a few seconds. Nausea, fatigue and hair loss are side effects of chemotherapy — this injection does not cause them.
I will be dangerously radioactive and cannot go near my family.
The radioactive element has a very short half-life and clears quickly. By the time you leave the scanning centre the level is already very low. Your team will give you any brief precautions before you go.
The injection could spread my cancer or make it worse.
The tracer does not affect cancer cells. It collects where cells use glucose rapidly — which includes many tumours — but it maps them, it does not alter them.
What do words like tracer and FDG actually mean?
- Radioactive tracer
- A substance tagged with a short-lived radioactive atom. When injected, it travels through the body and emits signals the scanner detects. It is used in very small amounts and clears from the body quickly.
- FDG (fluorodeoxyglucose)
- The most commonly used tracer for cancer PET scans. It behaves like glucose — the sugar cells use for energy — so it gathers in cells working hardest, including many tumours. That is how the scanner identifies areas of concern.
- Half-life
- The time it takes for half the radioactive material to decay naturally. The tracer used in most PET scans has a short half-life, which is why the radioactivity clears from your body within a few hours.
- Radiation dose
- The amount of ionising energy your body receives. PET scans involve a small, carefully calculated dose. Nuclear medicine specialists weigh the benefit of an accurate diagnosis against this dose before recommending the scan.
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 actually happens when you go for a PET scan?
- You fast for several hours before the scan — usually from midnight the night before. Water is allowed.
- A small amount of tracer is injected into a vein, usually in your arm.
- You rest quietly for about an hour while the tracer distributes through your body.
- The scan takes 20 to 40 minutes. You lie still on a flat table.
- You can eat and drink normally as soon as the scan is over.
- Drink extra water afterwards to help clear the tracer through your kidneys.
- You can travel home and be with family as usual.
What is in the injection, and does it cause side effects?
The injection contains a radioactive tracer — most often FDG, a form of glucose with a short-lived radioactive atom attached. The amount injected is very small, far less than a therapeutic drug dose.
Serious reactions to the tracer are rare. Allergic reactions occur in a very small proportion of patients, according to nuclear medicine guidance, and are usually mild. Your team asks about allergies when booking as a precaution.
The tracer does not cause the side effects of chemotherapy. There is no effect on your bone marrow, no hair loss, and no nausea from the injection itself.
Why do so many people think the PET scan injection is chemotherapy?
Both the tracer injection and chemotherapy are given at a cancer centre, often by the same team. That overlap is enough to blur the two together when you are frightened.
The distinction matters because this fear stops some people from accepting a scan that would give their treating team crucial information. A PET scan is a diagnostic tool — it shows where the cancer is and how it is behaving, which shapes every treatment decision that follows.
If you or a family member have been putting off a scan for this reason, tell your oncologist. The conversation takes a few minutes and removes a fear with no basis in what the injection actually contains.
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
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
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
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
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?
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
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Common questions
Frequently asked questions
How long does the tracer stay in my body?
The radioactive element decays quickly because it has a short half-life. Most of it has decayed or left your body in your urine within a few hours of the scan. Drinking extra water afterwards helps clear the remainder through your kidneys. By the following morning there is effectively none left. Your nuclear medicine team can give you the exact timing for the specific tracer used in your scan.
Is the injection safe if I am diabetic?
Diabetes requires special preparation because FDG, the tracer, behaves like glucose — high blood sugar at the time of the scan affects how well it works. Tell the team you are diabetic when the scan is booked, not on the day. They will give you specific instructions about food, insulin and diabetes medication beforehand. With the right preparation, people with diabetes have PET scans routinely and safely.
Can I be around children or pregnant family members after the scan?
There is a brief period after the scan when it is sensible to keep some distance from young children and pregnant women — typically a few hours. Your team will give you specific instructions before you leave. By the evening of the scan, this restriction is usually no longer needed. These instructions are standard and apply to every patient.
Will the injection affect my blood test results?
The tracer is present in the body in a very small amount and does not affect routine blood test results. It is metabolised and cleared quickly. If you have blood tests scheduled around the same time as your PET scan, let both teams know — in most cases there is no conflict, but it helps everyone coordinate.
Does the injection hurt?
The injection is no different from any other intravenous injection — a brief sharp sensation when the needle goes in, and occasionally a slight coolness as the tracer enters the vein. There is no burning and no pain afterwards. If you are anxious about needles, tell the team beforehand so they can take steps to make it easier.