• Manage the underlying cause or correct reversible causes if possible and appropriate.
• Try simple measures to relieve symptoms.
• Choose a first-line anti-emetic according to the cause of nausea and vomiting:
• Chemotherapy-induced: seek advice from the specialist supervising the person's chemotherapy.
• Drug-induced or metabolic causes: haloperidol, 1.5 mg at night and when required, increasing up to 10 mg/day.
• Intracranial disease: cyclizine, 25–50 mg three times a day and when required, up to a maximum of 150 mg/day; if intracranial pressure is raised, consider adding high-dose dexamethasone (e.g. 8–16 mg daily for up to 7 days, with subsequent reduction to 4–6 mg daily if possible). Stop dexamethasone if there is no obvious benefit within 3–5 days, or if it becomes ineffective.
• Movement-related (vestibular disorder): cyclizine 25–50 mg three times a day and when required, up to a maximum of 150 mg/day.
• Peristaltic failure or gastric stasis: metoclopramide, 10–20 mg three times a day (usually parenterally, unless mild) or 30–100 mg/24 hours via continuous subcutaneous infusion (CSCI). If extrapyramidal effects are a problem with metoclopramide use domperidone (30–60 mg rectally every 4–8 hours).
• Mechanical bowel obstruction:
• Exclude or treat constipation.
• Give cyclizine, 50–150 mg/24 hours via CSCI.
• If symptoms persist: add haloperidol, 2.5–10 mg/24 hours or as a single night-time dose, or levomepromazine, 5–25 mg/24 hours or as a single night-time dose.
• For colic and large-volume vomiting: hyoscine butylbromide, 20 mg immediately by subcutaneous injection, then 60–120 mg/24 hours via CSCI. If large-volume vomiting persists, consider octreotide (specialist palliative care advice is advised).
• Abdominal or pelvic tumour (causing distension, compression, or disturbance of abdominal or pelvic organs): give cyclizine 25–50 mg three times a day and when required (up to a maximum of 150 mg/day) or 75–150 mg/24 hours via CSCI.
• Anxiety-related: a benzodiazepine (e.g. lorazepam, 0.5–1 mg sublingually) or levomepromazine, 3–6 mg orally or 2.5–6.25 mg by subcutaneous injection.
• Ascertain the most appropriate route of administration of the anti-emetic.
• Prescribe anti-emetics regularly and as required.
• Review the effectiveness of anti-emetic treatment every 24 hours.
• Continue anti-emetics unless nausea and vomiting has resolved.

In depth