The short answer
Treatment may be held while an infection is active because another dose could push counts lower. A fever during chemotherapy is a medical emergency. Call your care team right away.
Treatment is usually held while an infection is active because another dose pushes counts lower at exactly the wrong moment.
The most common sources are a central line, the mouth and teeth, the chest, the urinary tract, skin and wounds, and the gut.
The threshold for immediate contact is a temperature of 100.4 degrees Fahrenheit (38°C) or higher, or the lower number your team gave you. One reading is enough.
Check with your team before taking acetaminophen or ibuprofen for a fever, because lowering the temperature can mask a serious problem.
On this page
Choose how you want to read this
The whole article, with every detail and caution.
This page is for people whose cancer treatment has been paused, or may be paused, because of an infection. It explains why, what happens next, and what to report.
Why an infection stops the schedule
Many cancer treatments reduce your ability to fight infection. Another dose while an infection is active pushes your counts lower. That happens at exactly the moment your body needs them. So treatment is usually held until the infection is under control. The pause is a deliberate safety step.
Where infections usually start
Infections usually start in a few places:
- Around a catheter or central line
- The mouth and throat
- The sinuses, ears and chest
- The urinary tract
- The skin
- The gut
Diarrhea can be a sign of infection. Tell your team about it. Do not treat yourself with anti-diarrheal medicine unless your team says so.
Dental infection is a special case. NCI advises a dental checkup at least a month before treatment starts. That gives the mouth time to heal from any dental work. Dental work can cause problems after radiation to the head or neck.
Neutropenic fever is an emergency
If your white cells are low and you develop a fever, this is treated as an emergency. Contact your team immediately at 100.4 degrees Fahrenheit (38°C) or higher, or at the lower number your team gave you. One reading is enough. The CDC says, "If you get a fever during your chemotherapy treatment, it's a medical emergency" (CDC).
NCI advises talking to your doctor or nurse before you take any medicine for a fever, including acetaminophen or ibuprofen. Lowering the temperature can mask a serious problem.
Here is what may follow:
- Blood tests
- Imaging tests, such as an x-ray or CT scan
- Samples of urine, stool, sputum or fluid from around a catheter
- Medicine started right away, while you wait for results
If you go to the emergency room, tell the person checking you in that you are being treated for cancer and are getting chemotherapy.
What a delay actually changes
Ask directly rather than assuming:
- How long is the pause expected to last?
- Does the whole schedule shift, or is a cycle skipped?
- Will the dose change when you restart?
- What has to be true, in test results or symptoms, before treatment resumes?
Ask too about growth factors. These are shots that help the bone marrow make more white blood cells.
If the infection involves a port or PICC, ask what that means for the line and for timing.
Delays feel like lost ground. But they are common, and they are planned for. A pause to treat an infection is not the same as treatment failing.
Reducing the chance of the next one
Several things lower your risk:
- Wash your hands often.
- Keep any line site clean and dry.
- Follow food safety rules. Cook meat, fish and eggs well.
- Clean your teeth well, and check your mouth for sores.
- Stay away from people who are sick, and avoid crowds.
- Ask your team about vaccines, including seasonal ones, and when in your cycle to have them.
- Ask before any dental work or planned procedure.
What to report, and how fast
Some problems need a call right away, and some need emergency care. Knowing which is which ahead of time makes a bad night easier.
Call immediately, day or night, for either of these:
- A fever at or above the threshold your team gave you
- Shaking chills, even without a measured temperature
Also call right away, at any hour, for any of these (CDC):
- A new cough or shortness of breath
- Burning on passing urine or new urinary frequency
- Redness, swelling, warmth, pus or pain at a line site, wound or skin break
- Mouth sores that stop you eating or drinking
- Diarrhea
- Sudden abdominal pain
Call 911 or go to an emergency department for any of these. Do not drive yourself:
- Confusion or unusual drowsiness
- Dizziness or fainting
- A rash that spreads quickly
- A stiff neck with headache
- An inability to keep fluids down
Sepsis can move fast in someone with low counts. Say you feel suddenly and unusually unwell during treatment. The safest assumption is that it needs assessing now rather than in the morning. Keep your team's after-hours number and a note of your current treatment and cycle date where you can find them.
Sources
Common questions
Why can't treatment just continue while I take antibiotics?
Many cancer treatments reduce your ability to fight infection. Giving another dose while an infection is active pushes your counts lower at the moment your body most needs them. The pause is a deliberate safety step, and it is one of the most common reasons a carefully planned schedule slips.
What happens when I call with a fever?
Expect tests to look for the cause. These may include blood tests, imaging, and samples of urine, stool or fluid from around a catheter. Your team may start medicine right away, while waiting for results, to keep the infection from getting worse.
How much time will I lose?
Ask directly rather than assuming. The useful questions are how long the pause is expected to last, whether the whole schedule shifts or a cycle is skipped, whether the dose changes when you restart, and what needs to be true in your results or symptoms before treatment resumes. Also ask whether a growth factor injection will be added to later cycles to reduce the chance of it recurring.
Will I lose my port or PICC?
Ask your team whether the infection involves your line and what that means for it. Swelling or redness at a catheter site is a sign of infection. Call your care team right away, at any hour, if you see it.
What about diarrhea during treatment?
Diarrhea can be a sign of infection. Tell your doctor or nurse about it rather than treating it yourself. Ask before taking any over-the-counter medicine.
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).
Talk with a trained specialist or navigator
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
Fever of 100.4°F (38°C) or higher during chemo, severe pain, or trouble breathing: call your cancer care team right away, day or night. Call 911 for an emergency.
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.
Written by: Cancer ExplainedSources last checked: 2026-07-30 what this meansLast updated: 2026-09-29Next planned review: 2027-01-30
Review details and limits
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, and this 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 then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
High-risk topic — talk to your care team. This topic can involve urgent, individual medical decisions. This page is general education only: it cannot tell you whether your situation is an emergency or what you personally should do. Follow your oncology team's instructions and contact them for individual guidance.
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.
Words to know
Tap any term to see what it means.
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, and this 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 then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. 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
- A Symptom Is Not a Diagnosis
- What Symptoms Should I Call My Oncology Team About Today?
- Cancer-Prevention Claims: Evidence, Uncertainty, or Myth?
- Deciding Whether to Get a Feeding Tube (PEG)
- Essential Dental Care Before Head & Neck Radiation
- PICC Line vs. Chemo Port: Comparing Central Lines
- Taking Oral Chemotherapy Safely at Home
- When Chemotherapy Is Delayed Due to Low Blood Counts