The short answer
CDC lists people receiving chemotherapy or radiation among those at higher risk of serious flu complications. Its immunization guidance treats inactivated influenza vaccine as the one vaccine not to postpone during chemotherapy or radiation, even though the immune response may be weaker. The nasal-spray flu vaccine is live and is not for people with weakened immune systems. Because it depends on your treatment, follow your care team's guidance first.
The inactivated flu shot is generally recommended for people with cancer.
Flu can be more serious during treatment, so protection matters.
The immune response may be weaker during chemotherapy, but the shot is still advised.
The nasal-spray flu vaccine is a live vaccine and is usually avoided during treatment.
Choose how you want to understand this
The full explanation.
Flu is not a small problem during chemotherapy
CDC keeps a list of people at higher risk of serious flu complications. Two entries on it apply here.
One covers people whose immune system is weakened by disease. It names some cancers, such as leukemia. The other covers people whose immune system is weakened by drugs. It names those getting chemotherapy or radiation for cancer.
So this question already has a clear answer. The flu shot is not a nice-to-have during treatment.
The shot is the one vaccine not to postpone
CDC's guidance for doctors on vaccines and weak immune systems makes two points.
The first is about safety. All non-live vaccines can be given safely to people whose immune system is not working normally. The injected flu vaccine is one of these.
The second is about timing, and it settles the question. CDC says that "except for inactivated influenza vaccine, vaccination during chemotherapy or radiation therapy should be avoided if possible because antibody response might be suboptimal."
Read that carefully. Most vaccines wait until treatment is over. The flu shot is the stated exception.
A weaker response is still a response
CDC is honest that the body may build less protection while the immune system is suppressed. That is why other vaccines wait.
It is also why CDC says something else worth knowing. Someone vaccinated in the 14 days before this kind of treatment starts, or during it, may be counted as not vaccinated at all. They may need the vaccine again, at least 3 months after treatment ends, once their immune system has recovered.
None of that is a reason to skip the flu shot. It is a reason to ask when to have it, and to ask later what needs repeating.
Why the nasal spray is off the list
The nasal spray is a live vaccine. It uses a weakened but living virus.
CDC's list of people who should not get it includes people with a weak immune system from any cause. CDC also says live vaccines should not be given for at least 3 months after treatment that suppresses the immune system. So the spray does not become an option the week chemotherapy ends.
When you go for your flu vaccine, say up front that you are in cancer treatment and need the shot, not the spray. Clinics do ask. Say it anyway.
The people around you should be vaccinated too
CDC's advice is that people who live with you, and others in close contact, should have all the vaccines that fit their age and situation. Smallpox vaccine is the one exception.
There is a catch, and it involves the spray again. CDC says a person who cares for someone with a very weak immune system in a protected environment should not have the nasal spray. If they do have it, they should stay away from that person for 7 days.
Most people in treatment are not in a protected environment. If you are, or a transplant is coming, tell your household to ask for the shot.
A vaccine does not replace the rest
NCI's infection advice still holds through flu season. Wash your hands often and well, and ask the people around you to do the same. Stay away from anyone who is sick or has a cold. Avoid crowds.
And know your fever number. CDC tells people on chemotherapy to call at once at 100.4°F (38°C) or higher, and calls a fever during chemotherapy a medical emergency. That holds whether or not you have had a flu shot.
What to ask your team
- Do you want me to have the flu vaccine, and when?
- Should I have it at the cancer center or at my own clinic?
- Will any of my vaccines need repeating after treatment ends?
- Should the people I live with be vaccinated, and does anyone need to avoid the spray?
This is general information. Your care team's specific instructions for your treatment always take priority.
Sources
Words to know
Tap any term to see what it means.
Common questions
Can I get a flu shot during chemotherapy?
Usually yes. CDC lists people getting chemotherapy or radiation among those at higher risk of serious flu complications, and its immunization guidance names inactivated influenza vaccine as the one not to postpone during treatment. The nasal-spray version is live and is not used. Ask your team when they want you to have it.
Why is the nasal-spray flu vaccine avoided during treatment?
The nasal spray is a live vaccine, made with a weakened live virus. Live vaccines are generally avoided during cancer treatment because a weakened immune system may not handle them safely. The flu shot (given by injection) is inactivated, not live, which is why it's the usual choice.
Does the flu shot work as well during chemo?
The response may be weaker while the immune system is suppressed. CDC immunization guidance still singles out inactivated influenza vaccine as the exception that should not be postponed during chemotherapy or radiation therapy. Ask your team when they want you to have it.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
Your next step
Your care team's answer depends on your treatment — ask them directly.
Speak With Trained Specialists & Human Navigators
Cancer Explained provides educational guidance, but does not replace trained specialists, social workers, or your medical team.
Talk to a trained cancer information specialist
Free, confidential assistance from NCI Cancer Information Service via phone, chat, or email.
Contact your oncology team
Locate after-hours contact numbers, portal messages, or urgent triage phone lines.
Find a patient navigator
Get one-on-one help with appointments, logistics, translation, and care coordination.
Find a genetic counselor
Discuss inherited mutation risk, family history, and genetic testing options.
Find an oncology social worker
Access emotional counseling, family support groups, and mental health resources.
Find a financial navigator
Locate copay assistance foundations, grant programs, and lodging/travel support.
Find a clinical-trial specialist
Search matching studies and speak with NCI trial information specialists.
Get urgent help
Immediate emergency guidance for fever (>100.4°F during chemo), severe pain, or shortness of breath.
Help Us Improve This Guide
Did this explanation answer your question and help you determine your next step?
Know someone who needs this?
Plenty of people are looking for something like this and do not know where to start. If this would help a friend or someone you love, send it on — we have written an opening line so you do not have to stare at an empty message. You can change every word of it.
Your message is written and sent in your own email or messaging app — we never see who you send it to, and nothing is added to any list.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Last updated: 2026-08-09Next planned review: 2028-07-14
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.
General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team 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.
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.
Read more about our editorial process, our use of AI, and our corrections policy.
Spotted a problem? Report an error — a factual mistake, broken or outdated source, confusing wording, or anything that seems unsafe. Please do not include names, medical record numbers, dates of birth, addresses, or other identifying medical information in your report.
After using this page, do you understand what to do next?
Anonymous — we only record the answer, never who gave it.
Related articles
Still have questions?
Educational answers, plain language
Free to print and share