Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Vomiting with sepsis, obstruction, pressure or metabolic collapse
Haemodynamic compromise, fever after systemic treatment, severe abdominal distension or pain, peritonism, faeculent or bloody vomit, focal neurological change, reduced consciousness or profound dehydration and electrolyte loss requires emergency diagnosis rather than further oral antiemetics alone.
Action: Use ABCDE care, isolate and treat suspected neutropenic sepsis immediately, obtain intravenous access, blood count, renal and electrolyte tests and cause-directed imaging. Replace fluid and potassium or magnesium safely, decompress suspected obstruction when indicated and use an intravenous, subcutaneous or buccal antiemetic route while oral absorption is unreliable.
Synopsis
Prevent treatment-related emesis from the first cycle, identify acute, delayed, breakthrough, refractory and anticipatory patterns, exclude dangerous competing causes and match antiemetic class, route, schedule and rescue to regimen risk and patient factors.
Classify symptoms as acute within 24 hours, delayed after 24 hours, breakthrough despite prophylaxis, refractory in later cycles or anticipatory before treatment.
First-line prevention is chosen from the complete regimen’s emetogenic risk, not from the most familiar drug or the severity of symptoms after they begin.
Before every cycle, review what was prescribed, what was actually taken, timing, vomiting count, nausea burden, rescue use, constipation, sedation and cycle-specific control.
Key red flags
Fever, rigors, hypotension, confusion or new oxygen requirement after systemic anticancer treatment is neutropenic sepsis until treated immediately.
Dehydration and electrolyte loss
Postural dizziness, tachycardia, dry mouth, oliguria, weakness or arrhythmia requires urgent renal, potassium and magnesium assessment and replacement.
Investigation priorities
01
First-line structured symptom and regimen reviewFirst stepFirst line
Classify timing, severity, emetogenic risk, actual prophylaxis, adherence, rescue use, bowel pattern and individual susceptibility.
Management branches
Before treatmentBuild prophylaxis from emetogenic risk
A systemic or radiation treatment course with potential emesis is prescribed.
Classify the complete regimen and radiation field, then add age, sex, alcohol history, motion sickness, pregnancy sickness, anxiety and previous-cycle control.
Prescribe the protocol combination before exposure with exact delayed-day doses, rescue from a different class and constipation, sedation and interaction counselling.
Key medicines
OndansetronFor moderately emetogenic chemotherapy, a licensed oral schedule is 8 mg one to two hours before treatment, 8 mg twelve hours later, then 8 mg twice daily for up to five days; follow the regimen-specific protocol.
AprepitantGive aprepitant 125 mg orally one hour before chemotherapy on day 1, then 80 mg once daily on days 2 and 3 as part of the licensed combination regimen.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.