The short answer
This page walks you through a bone scan step by step, from preparation and the tracer injection to the wait, the scan, and results. It is general education, not individual medical advice.
A bone scan uses a small amount of radioactive tracer to find abnormal areas in bone, including cancer that has spread.
For cancer staging, pictures are usually taken 3 to 4 hours after the injection, and the scanning itself lasts about 1 hour.
The needle stick is the only painful part; the scan itself does not hurt, though holding still can be uncomfortable.
The tracer amount is very small, and all the radiation is gone from your body within 2 to 3 days.
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The full explanation.
A bone scan is a two-part imaging test: a quick injection of a radioactive tracer, then pictures taken hours later once the tracer has settled into your bones. Knowing how to prepare for a bone scan, and what the waiting is for, takes most of the stress out of the day. Here is what to expect, step by step, based on MedlinePlus and the National Cancer Institute.
What is a bone scan and why is it done?
A bone scan is a nuclear medicine test. NCI explains that a small amount of radioactive material, called a tracer, is injected into a vein. As it circulates, the material collects in abnormal areas of bone. A special camera then takes pictures, and the areas where tracer gathers show up as "hot spots."
Doctors use bone scans to check for abnormal areas or damage in the bones. In cancer care, NCI says the test helps diagnose bone cancer or find out whether a cancer that started elsewhere has spread to the bones. It can also be used for other bone problems, such as infection.
If your team is choosing between tests, our page comparing a bone scan and a PET scan explains how they differ.
How do I prepare for a bone scan?
Preparation is light, but a few points matter:
- Bismuth medicines. MedlinePlus says not to take any medicine containing bismuth, such as Pepto-Bismol, for 4 days before the test. It can interfere with the pictures.
- Metal. You will remove jewelry and other metal objects, and you may be asked to wear a gown.
- Pregnancy and breastfeeding. Tell your provider before the test if you are or might be pregnant. The test may be postponed. If you are breastfeeding, the guidance is to pump and throw away the milk for the next 3 days after the injection.
- Eating. Ask your own facility for instructions. Bring something to fill the waiting hours, such as a book.
What happens during the test?
The injection. The tracer goes into a vein in your arm. MedlinePlus notes there is a small amount of pain when the needle goes in. The substance then travels through your blood to your bones and organs.
The wait. When the question is whether cancer has spread, pictures are taken after a delay of 3 to 4 hours, when the tracer has collected in the bones. If the scan is being done to look for infection, images may be taken right after the injection and again 3 to 4 hours later. Many centers let you leave during the wait; ask when you check in.
The scan. You lie on a table while the camera moves around you. The scanning part lasts about 1 hour. You may need to change positions so the camera can capture different views. There is no pain during the scan. The hard part for most people is simply lying still, so tell the staff ahead of time if you have pain or trouble with certain positions.
Is the radiation something to worry about?
The amount of radioactive material injected into your vein is very small. MedlinePlus states that all the radiation is gone from your body within 2 to 3 days. Drinking extra water afterward helps flush the tracer from your bladder.
After the test, drink extra water to help flush the tracer from your bladder. If you have wondered about tracers and being around other people, our page on radioactivity after a PET scan covers the same kind of question for a related test.
What do the results mean?
A normal result means the tracer spread evenly through the bones. An abnormal result shows hot spots, where extra tracer collected, or cold spots, where less collected.
A hot spot is a flag, not a diagnosis. Many bone problems can light up on a scan, so your doctor reads the pattern alongside your history and other tests. NCI also notes something practical: results from imaging tests are often posted to your patient portal before your doctor can discuss them. If you see the report first, hold your conclusions. Your doctor is the best person to explain what the findings mean for you, and to lay out any next steps. Ask before the scan when and how you will hear about results, so you are not left refreshing a screen.
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Common questions
How long does a bone scan take?
Plan for most of a day at the facility, but not constant activity. MedlinePlus says the tracer needs 3 to 4 hours to collect in your bones after the injection, and the scanning part of the test lasts about 1 hour. Many centers let you leave and come back during the wait.
Does a bone scan hurt?
MedlinePlus says there is a small amount of pain when the needle is inserted, and no pain during the scan itself. Lying still for the scan can be uncomfortable, so mention pain problems to the staff beforehand so they can help position you.
Is the radiation from a bone scan dangerous?
The amount of radioactive material injected is very small, and MedlinePlus states all of it is gone from your body within 2 to 3 days. Tell your provider before the test if you are pregnant or breastfeeding, since the test may be postponed or need extra precautions.
What does a hot spot on a bone scan mean?
A hot spot is an area where more tracer collected, and a cold spot is an area with less. NCI notes the tracer collects in abnormal areas of bone. Abnormal does not automatically mean cancer, so your doctor interprets the pattern together with your other tests.
Questions to ask your doctor
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Your next step
Get ready with a checklist and questions for the visit.
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Sources last checked: 2026-08-21 what this meansLast updated: 2026-08-21Next planned review: 2027-08-21
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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