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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.

Common GI drug classes and safe prescribing

Gastroenterology and hepatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull

Synopsis

Choose common gastrointestinal medicines by mechanism and diagnosis, prescribe a defined course, and prevent QT, neurological, anticholinergic, electrolyte, interaction, obstruction and masking harms.

  • Treat the cause and dangerous alternatives before suppressing a symptom: antiemetics, antidiarrhoeals, antispasmodics and laxatives can obscure obstruction, sepsis, bleeding or inflammatory disease.
  • For every GI drug, write the indication, intended duration, review or stop point, renal and hepatic considerations, pregnancy context, interactions and what response would justify continuation.
  • Proton-pump inhibitors are effective for acid-mediated disease and gastroprotection when risk warrants it, but lowest effective intensity and review reduce unnecessary long-term exposure and rebound-driven continuation.
  • Metoclopramide
is restricted to short-term use because of neurological harm; the MHRA adult maximum is 30 mg daily and treatment should not usually exceed five days.
  • Domperidone carries cardiac risk, should use the lowest effective dose for the shortest duration, and is contraindicated in cardiac conduction risk, important interacting medicines and, since 2026, phaeochromocytoma.
  • Choose laxatives from stool pattern and mechanism after excluding obstruction: bulk-forming agents need adequate fluid, osmotics retain water, and stimulants enhance propulsion.
  • Loperamide is inappropriate in ileus, toxic megacolon risk or severe bloody inflammatory or infectious diarrhoea; excessive dosing can cause fatal ventricular arrhythmia.
  • Bile acid sequestrants can improve confirmed or strongly suspected bile acid diarrhoea but bind other medicines and may impair fat-soluble vitamin absorption, so timing and follow-up matter.

    • Key red flags

    Persistent vomiting with distension, severe pain, absent stool or flatus, dehydration or peritonism requires urgent obstruction or acute-abdomen assessment before prokinetics, laxatives or oral medicines.

    Haematemesis, melaena, haemodynamic compromise or progressive dysphagia needs urgent diagnostic management and must not be masked by empirical acid suppression alone.

    Bloody diarrhoea with fever, severe tenderness, dilatation or systemic toxicity raises infectious colitis, inflammatory flare or toxic megacolon risk; avoid loperamide pending expert assessment.

    Syncope, palpitations, seizure or new ventricular ectopy while taking domperidone, ondansetron, high-dose loperamide or interacting QT medicines requires immediate ECG and electrolyte evaluation.

    Oculogyric crisis, dystonia, akathisia or parkinsonism after metoclopramide should prompt drug cessation and urgent clinical review rather than another antiemetic dose.

    Investigation priorities

    01
    Structured medication reconciliationFirst step

    Identify active indications, duplicate mechanisms, interactions, self-medication and prescriptions that have outlived their purpose.

    Management branches

    CHECKBefore prescribing a GI symptom drug

    A patient requests treatment for pain, nausea, reflux, constipation or diarrhoea.

    1. Define symptom chronology, likely mechanism, red flags, comorbidity, pregnancy possibility and current prescription or non-prescription exposure.
    2. Examine and investigate enough to exclude an acute abdomen, bleeding, severe infection or metabolic emergency before suppressing the signal.
    3. Choose the narrowest effective agent using the current BNF, SmPC and local formulary, with organ-function and interaction checks.
    4. Write indication, course, response target, adverse-effect advice and a dated stop or review instruction.

    Key medicines

    Proton-pump inhibitorUse the BNF regimen matching the licensed indication, then step down to the lowest effective intensity or stop after the planned course.Check interactions and ongoing indication; prolonged therapy is associated with hypomagnesaemia and other infection, bone or nutrient concerns, while abrupt cessation can cause rebound symptoms.
    MetoclopramideFor adults, do not exceed 10 mg up to three times daily or 30 mg daily, and usually limit treatment to five days.Avoid in Parkinson's disease, gastrointestinal obstruction or bleeding and previous tardive dyskinesia; reduce as required for organ dysfunction and stop for extrapyramidal reactions.
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    Sources and review status8 sources · checked 27 Aug 2026 · clinical review pending+
    Sources

    Sources and review status

    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.

    • NICE BNF Dyspepsia and refluxCurrent UK acid-suppression and gastroprotection prescribing context.
    • NICE BNF ConstipationLaxative class selection and treatment sequence.
    • NICE BNF DiarrhoeaAntimotility indications, exclusions and rehydration priorities.
    • MHRA Metoclopramide neurological safetyUK dose, duration and neurological restrictions.
    • MHRA Domperidone cardiac safetyUK cardiac contraindications, maximum adult dose and duration.
    • MHRA Domperidone phaeochromocytoma contraindicationCurrent July 2026 regulatory update for severe hypertensive risk.
    • MHRA Loperamide cardiac reactionsVentricular arrhythmia risk with excessive or misused dosing.
    • MHRA PPI hypomagnesaemia warningMonitoring implications for prolonged acid suppression.

    Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

    Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom