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Antiemetic (Phenothiazine — Dopamine D₂ Antagonist) Pregnancy: Caution — phenothiazines have been used in pregnancy for hyperemesis gravidarum; neonatal extrapyramidal effects reported with third trimester use. Avoid if possible; use only short courses.

Prochlorperazine

Brand names: Stemetil, Buccastem M

Adult dose

Dose: Oral: 5–10mg two to three times daily. Buccal (Buccastem M): 3mg twice daily (placed between upper lip and gum and left to dissolve). IM: 12.5mg (max 25mg/day IM). Severe nausea: 20mg orally, then 10mg after 2 hours.
Route: Oral, buccal, IM
Frequency: Two to three times daily (oral/buccal); as needed (IM)
Max: 30mg/day (oral); 25mg/day (IM)
Buccal route (Buccastem M) avoids first-pass metabolism and useful when vomiting prevents oral intake. IM injection painful — give deeply into gluteal muscle. Not for IV use (risk of severe hypotension). Treat acute dystonic reaction with procyclidine 5mg IV or IM.

Paediatric dose

Route: Oral
Frequency: Two to three times daily
Max: Seek specialist opinion
Not recommended in children <12 years — high risk of extrapyramidal reactions (particularly acute dystonia). Children 12–17 years: 5–10mg BD–TDS under medical supervision. Seek specialist opinion for use in younger children. Source: BNF for Children 2024.

Dose adjustments

Renal

No dose adjustment required; use with caution in severe renal impairment.

Hepatic

Use with caution — hepatotoxicity risk; avoid in hepatic failure.

Clinical pearls

  • Antidote for acute dystonic reaction: procyclidine 5mg IV or IM (or biperiden 5mg IV). Resolves within 20 minutes. Warn patient it may recur — document allergy/reaction.
  • Buccal preparation (Buccastem M 3mg): placed between upper lip and gum — dissolves over 1–2 hours. Bypasses GI absorption and useful in active vomiting.
  • Avoid in Parkinson's disease — use domperidone instead (peripheral D₂ antagonist, does not cross BBB).
  • Tardive dyskinesia: potentially irreversible involuntary movements with long-term use — use the lowest effective dose for the shortest duration; reassess regularly.

Contraindications

  • Parkinson's disease (dopamine antagonism worsens motor symptoms)
  • Phaeochromocytoma
  • Severe hepatic impairment
  • Bone marrow depression
  • CNS depression

Side effects

  • Extrapyramidal reactions — acute dystonia (oculogyric crisis, torticollis, trismus): treat with procyclidine 5mg IV/IM. More common in young adults and first dose.
  • Tardive dyskinesia (prolonged use — may be irreversible)
  • Drowsiness
  • Hypotension (especially IM)
  • Hyperprolactinaemia
  • QT prolongation (rare)

Interactions

  • Levodopa / dopaminergic drugs: antagonism — avoid in Parkinson's disease
  • Lithium: increased risk of neurotoxicity and extrapyramidal effects
  • QT-prolonging drugs: additive risk
  • Antihypertensives: enhanced hypotensive effect
  • Alcohol: enhanced sedation

Monitoring

  • Signs of extrapyramidal reactions
  • QTc (if prolonged use or cardiac risk)
  • Tardive dyskinesia (long-term)

Reference: BNFc; BNF 90; NICE NG121 Nausea and Vomiting in Pregnancy; SPC Stemetil. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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