Medical Oncologist
Emergency guidance
Diarrhoea During Cancer Treatment: — When to Go to Hospital
Diarrhoea during cancer treatment can become dangerous quickly. Some signs mean go to the emergency department right now. Others mean call your oncology team today — not at your next scheduled appointment.
Medically reviewed by Dr. C. Raghavendra Reddy, Medical Oncologist, MBBS (Gold Medal) · DNB · DM (Medical Oncology, Gold Medal) · Last reviewed August 2026
- Blood is always urgent — Any blood or mucus in your stool during treatment needs emergency review today.
- Dehydration moves fast — If you cannot keep fluids down, you cannot wait. Go to hospital now.
- Change from baseline matters most — The question is not a count — it is how much more than your usual, and whether it is getting worse.
- Call before taking anything — Do not take anti-diarrhoeal medicine without speaking to your team first.
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Go to hospital now if you have blood in your stool, cannot keep fluids down, have a fever, or have severe abdominal pain. Call your oncology team today if diarrhoea has clearly increased from your usual pattern and is not settling. NCCN and ASCO treat both as needing urgent review, not a wait-and-see approach.
If a symptom below applies to you, do not wait for a callback. Call 1800-202-8726 or go to your nearest emergency department.
When should you call your oncology team today?
Call the same day — not your next appointment — if diarrhoea has clearly increased from your usual pattern and has not settled after 24 hours.
Call if you feel worse rather than better after a day of steady fluids, even without the emergency signs above.
Do not take loperamide or any pharmacy anti-diarrhoeal before calling. These can suppress the symptom while the underlying cause continues, and they hide the worsening your team is watching for.
If you are unsure whether to call or go straight to hospital, call. Your team will tell you which to do. The CION helpline is available for exactly this question.
Meet the Specialists
17+ senior cancer specialists. One panel for your case.
Trained at AIIMS, Tata Memorial, and leading international centres. Combined 150+ years of experience. Every complex case is reviewed by 3+ of them — together.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
Surgical Oncologist
Surgical Oncologist
Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
Surgical Oncologist
Radiation Oncologist
Radiation Oncologist
Radiation Oncologist
Hematologist
Interventional Radiologist
Dr. Mohammed Imran
Surgical Oncologist
Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
Surgical Oncologist
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Not sure whether this counts as an emergency?
Call the helpline. It is always better to check than to wait.
What should you tell your team when you call?
- How your bowel habit has changed from your usual — not just today, but over the past two to three days
- Whether there is any blood, mucus, or dark-coloured stool
- Whether you have fever, abdominal pain, or cramping
- Whether you can still drink and keep fluids down
- Which treatment you are on and when your last dose was
- Anything you have already taken for the diarrhoea, including home remedies or pharmacy medicines
Is my diarrhoea serious enough to act on?
| Sign | Monitor at home | Call today | Go to hospital now |
|---|---|---|---|
| Stool frequency | Slightly more than usual, settling on its own | Clearly more than your baseline, not improving after 24 hours | Continuous or rapidly worsening |
| Blood or mucus | None | None — but call immediately if any appears | Any blood or mucus at all |
| Fever | None | Low-grade, stable — contact team | Any fever alongside diarrhoea |
| Abdominal pain | Mild cramping, brief | Ongoing or getting worse | Severe pain or hard, swollen belly |
| Fluid intake | Drinking normally and keeping fluids down | Struggling to keep up with losses | Cannot keep fluids down at all |
| Dizziness or confusion | None | Mild — mention to your team | Any faintness or confusion — go now |
| Typically starts | Can occur at any point during treatment | Often after several cycles, but can be anytime | Can occur at any point — do not wait to see if it passes |
| What to do | Rest, fluids, watch closely | Call your oncology team today | Go to the emergency department now |
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Common questions
Frequently asked questions
How many loose motions a day are dangerous during cancer treatment?
There is no single number that is safe or dangerous, and your own usual pattern matters more than a count. What your team needs to know is the change: how much more than your usual, whether it is getting worse day on day, and whether there is blood, fever, pain or vomiting alongside it. Any clear increase that does not settle after 24 hours — or any blood at all — means call today. The emergency signs listed above mean go to hospital now, regardless of how many times you have been.
Can I take Imodium or loperamide while on cancer treatment?
Not without speaking to your oncology team first. Anti-diarrhoeal medicines can settle the symptom while the underlying cause continues, which delays the treatment that actually helps and hides the worsening your team needs to see. This is especially important on immunotherapy, where diarrhoea can be an early sign of immune colitis — an inflammation that needs specific treatment with steroids, not anti-diarrhoeal tablets. If your team has already told you that loperamide is appropriate for your situation, follow their advice. Otherwise, call before taking anything.
Is diarrhoea more dangerous on immunotherapy than on chemotherapy?
Both are serious, but for different reasons. On chemotherapy, the main risks are dehydration and infection, which can develop quickly if the gut lining is damaged. On immunotherapy, diarrhoea can be an early sign of immune colitis — the immune system inflaming the gut — which needs treatment with steroids rather than fluids alone. The emergency signs are the same for both: blood, fever, severe pain, or inability to keep fluids down. If your bowel habit has clearly changed on either treatment, call your team the same day.
What should I tell the emergency department when I arrive?
Tell the triage nurse immediately that you are on active cancer treatment. Patients undergoing treatment are usually prioritised at triage because their immune system may be compromised. Bring a list of your current medicines and the name of your treatment centre if you can. You will likely have blood tests to check for signs of infection and dehydration, and fluids may be started through a drip. Your oncology team will usually be contacted once you are assessed.