# Irinotecan: early cholinergic syndrome and late diarrhoea

Source: https://onco.cc/protocols/irinotecan-early-cholinergic-syndrome-and-late-diarrhoea/  
OnCo record `irinotecan-early-cholinergic-syndrome-and-late-diarrhoea` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Irinotecan can cause two kinds of diarrhoea. The first comes during or soon after the drip, with sweating, watery eyes and cramps; an atropine injection stops it. The second starts a day or more later and can be serious: take 4 mg of loperamide at the first loose stool, then 2 mg every 2 hours, and call your team if it is not controlled in 24 hours, or with blood, fever or faintness.

## Summary

Irinotecan causes an early diarrhoea during or shortly after the infusion, part of an acute cholinergic syndrome (rhinitis, salivation, miosis, lacrimation, sweating, flushing, cramps, sometimes bradycardia), and a late diarrhoea, generally more than 24 hours after the dose (median onset 5 days with 3-weekly and 11 days with weekly dosing), which can be prolonged and life-threatening. The US label advises considering atropine 0.25 to 1 mg intravenously or subcutaneously as prophylaxis or treatment for the cholinergic syndrome; eviQ gives 0.3 to 0.6 mg, repeated to a maximum of 1.2 mg. For late diarrhoea the label and eviQ agree on high-dose loperamide (4 mg at the first loose stool, then 2 mg every 2 hours until 12 hours free of diarrhoea, 4 mg every 4 hours at night), not for more than 48 hours because of paralytic ileus. Fever, dehydration or melaena means admission, stool tests, intravenous fluids and antibiotics; diarrhoea unresolved after a second 12 to 24 hour review is treated with octreotide. The next dose waits until bowel function has been normal without antidiarrhoeals for 24 hours, and the dose is reduced if grade 2 to 4 late diarrhoea recurs. eviQ applies the same algorithm to sacituzumab govitecan, whose label caps loperamide at 16 mg a day.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: irinotecan cholinergic syndrome; atropine with irinotecan; irinotecan late diarrhoea; high-dose loperamide after irinotecan; sacituzumab govitecan diarrhoea; CPT-11 diarrhoea
- Tags: protocol; diarrhoea; supportive-care

## Connected records

- protocols: [Diarrhoea from chemotherapy, targeted therapy and radiotherapy: grading, loperamide, octreotide and when to admit](https://onco.cc/protocols/treatment-induced-diarrhoea-grading-and-management/), [Suspected febrile neutropenia (neutropenic sepsis): the first hour](https://onco.cc/protocols/febrile-neutropenia-first-hour/)
- drugs: [FOLFIRI (5-FU, leucovorin, irinotecan)](https://onco.cc/drugs/folfiri/), [FOLFOXIRI (5-FU, leucovorin, oxaliplatin, irinotecan)](https://onco.cc/drugs/folfoxiri/), [Irinotecan (and liposomal irinotecan)](https://onco.cc/drugs/irinotecan/), [Sacituzumab govitecan](https://onco.cc/drugs/sacituzumab-govitecan/), [Somatostatin analogues (octreotide, lanreotide)](https://onco.cc/drugs/octreotide-lanreotide/)
- fronts: [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- technologies: [UGT1A1 genotyping before irinotecan](https://onco.cc/technologies/ugt1a1-genotyping/)
- targets: [UGT1A1](https://onco.cc/targets/ugt1a1/)
- companies: [Pfizer (incl. Seagen)](https://onco.cc/companies/pfizer/)
- institutions: [National Cancer Institute (NIH)](https://onco.cc/institutions/nci/)
- terms: [CTCAE toxicity grading (grade 3-4 adverse events)](https://onco.cc/terms/ctcae-grading/), [Febrile neutropenia](https://onco.cc/terms/febrile-neutropenia/), [Living with FOLFIRINOX, NALIRIFOX and gemcitabine with nab-paclitaxel](https://onco.cc/terms/chemotherapy-side-effects-pancreatic/), [Living with FOLFOX, CAPOX, FOLFIRI and the EGFR antibodies](https://onco.cc/terms/chemotherapy-side-effects-colorectal/)
- ideas: [Test DPYD, UGT1A1 and TPMT/NUDT15 before the first dose, everywhere](https://onco.cc/ideas/idea-tr1-pre-emptive-pharmacogenomic-testing/)

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