The short answer
Constipation is common in treatment, often from certain chemo drugs, anti-nausea or pain medicines, and being less active. Fluids, fiber (if your team agrees), gentle movement, and a regular routine can help. Tell your team if you have not had a bowel movement in a few days, or with pain, so they can help safely.
Some chemo drugs, anti-nausea medicines, and pain medicines (opioids) commonly cause constipation.
Fluids, fiber, and gentle activity may help — but check with your team before big fiber changes.
A regular toilet routine and not ignoring the urge can make a difference.
Do not start laxatives on your own during treatment without checking with your team.
Choose how you want to understand this
The full explanation.
Why constipation happens in treatment
Constipation means hard, infrequent, or difficult bowel movements. It is common during cancer treatment. Some chemotherapy drugs slow the bowel. Many anti-nausea and pain medicines cause it too, especially opioids. Eating and drinking less, moving less, and changes in routine all add to it. Several treatment-related causes often stack up. So constipation is worth mentioning early rather than waiting.
Food and drink that may help
Drinking enough fluid is one of the most helpful steps. Fiber works best with plenty of water. Fiber-rich foods help many people. Good choices are whole grains, fruits, vegetables, beans, and prunes or prune juice. A warm drink in the morning gets things moving for some people. But more fiber is not always right. Check with your team first if your blood counts are low, or if your bowel is not working normally.
Movement and routine
Gentle activity helps the bowel move, even short walks as you are able. Set aside unhurried time to use the toilet, often after a meal. Answer the urge rather than holding it. Both habits help your body settle into a rhythm. Propping your feet on a low stool makes going easier for some people.
About laxatives
Many people on constipating medicines are given a bowel plan by their team. Still, do not start laxatives, enemas, or suppositories on your own during treatment. Check with your team first. They are not safe for everyone. Enemas and suppositories can be risky when blood counts are low. Everyone's situation is different. This is general information, not advice for you personally. Your care team can tailor it, and so can an oncology dietitian if one is available.
When to get help sooner
Constipation can be more than uncomfortable. A blocked bowel is an emergency, and stool that has become stuck needs treatment.
- Call 911 or go to an emergency department if you have severe belly pain with a hard, swollen belly, you are vomiting and cannot stop, or you are vomiting material that looks or smells like stool. Those point to a blocked bowel.
- Call your doctor immediately if your temperature reaches 100.4°F (38°C) or higher while you are on chemotherapy. CDC calls a fever during chemotherapy a medical emergency and says to call immediately, whether or not your belly hurts. If you do end up in an emergency room, tell the staff you are having chemotherapy.
- Call your care team the same day if you have had no bowel movement for three days or more, or you are passing only small amounts of liquid stool after days of constipation.
- Call your care team the same day if you see blood in your stool.
- Call your care team within a day or two if you have ongoing cramping, bloating, or straining, or your bowel plan has stopped working.
Sources
Words to know
Tap any term to see what it means.
Common questions
Why am I constipated during treatment?
Common causes include certain chemo drugs, anti-nausea and pain medicines (especially opioids), eating and drinking less, and being less active. Often several add up.
What foods help with constipation?
Fluids plus fiber from whole grains, fruits, vegetables, beans, and prunes help many people. Fiber works best with plenty of water. Check with your team if your counts are low.
Can I take a laxative?
Ask your team first. Many people on constipating medicines get a planned bowel regimen, but laxatives, enemas, and suppositories are not safe for everyone during treatment.
When should I call?
Call if you have not had a bowel movement in a few days, or have belly pain, cramping, bloating, nausea, or vomiting.
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).
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.
Knowledge Check
0 of 3 answered
This self-assessment checks understanding of educational content only. It is not medical advice.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Sources last checked: 2026-08-13 what this meansLast updated: 2026-08-18Next planned review: 2027-07-13
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 — Editorial review complete. This page completed Cancer Explained's editorial checks (sources, safety, plain language, duplication). It has not been reviewed by a physician or other healthcare professional.
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: Editorial review complete — This page completed Cancer Explained's editorial checks (sources, safety, plain language, duplication). It has not been reviewed by a physician or other healthcare professional.
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