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Antihistamine Antiemetic Pregnancy: Use with caution in first trimester; generally considered safe in second and third trimester for short-term use

Cyclizine

Brand names: Valoid

Adult dose

Dose: 50 mg three times daily
Route: Oral / IV / IM
Frequency: Up to three times daily
Max: 150 mg/day
IV: give slowly over 3-5 minutes. Useful for opioid-induced nausea (palliative care), motion sickness, and postoperative nausea

Paediatric dose

Dose: Seek specialist opinion N/A/kg
Route: Oral / IV / IM
Frequency: Seek specialist opinion
Max: Seek specialist opinion
Seek specialist opinion

Dose adjustments

Renal

Use with caution

Hepatic

Use with caution in severe hepatic impairment

Paediatric weight-based calculator

Seek specialist opinion

Clinical pearls

  • Anticholinergic burden (ACB score 1-2) — use with caution in elderly with cognitive impairment or at risk of urinary retention (BPH)
  • Preferred antiemetic in palliative care for opioid-induced nausea — effective via subcutaneous infusion (syringe driver)
  • STOPP v3: Antihistamine antiemetics are potentially inappropriate in elderly due to anticholinergic effects — consider ondansetron or metoclopramide (short-term) for alternative options
  • Tachycardia with rapid IV administration — always give slowly
  • Paradoxical excitation (agitation, confusion) can occur in elderly — if this develops, discontinue and switch antiemetic class

Contraindications

  • Urinary retention
  • Narrow-angle glaucoma
  • Pyloric stenosis

Side effects

  • Sedation
  • Dry mouth
  • Urinary retention
  • Constipation
  • Blurred vision
  • Tachycardia (IV administration)
  • Paradoxical excitation (elderly)

Interactions

  • Anticholinergics (additive effects)
  • CNS depressants (additive sedation)
  • Alcohol (enhanced sedation)

Monitoring

  • Sedation
  • Anticholinergic effects (urinary retention, confusion)
  • Heart rate (IV use)

Reference: BNFc; BNF 90; STOPP/START v3; AGS Beers Criteria 2023; Palliative Care Formulary. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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