Phenothiazine Antiemetic — Hyperemesis Gravidarum Pregnancy: SPC §4.6: there is inadequate evidence of safety in human pregnancy; the buccal tablets should be avoided unless absolutely necessary during the first trimester. Neonates exposed to antipsychotics (including prochlorperazine) during the third trimester are at risk of extrapyramidal and/or withdrawal symptoms (agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, feeding disorder) — newborns should be monitored carefully. Animal data show prochlorperazine may be found in breast milk, so it should not be used during lactation.

Prochlorperazine (Nausea and Vomiting in Pregnancy)

Brand names: Stemetil, Buccastem

Prochlorperazine is a phenothiazine antiemetic used here for nausea and vomiting in pregnancy, typically as a second-line option after first-line antihistamine antiemetics.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One or two 3 mg buccal tablets (3–6 mg)

Route: Buccal — place in the buccal cavity, high up along the top gum under the upper lip, until dissolved; do not chew or swallow the tablet

Frequency: Twice a day

eMC §4.2 verbatim (Prochlorperazine 3 mg Buccal Tablets): 'Adults and children aged 12 years and over: One or two tablets twice a day. Children under 12 years: Not recommended. Elderly patients: There is no evidence that dosage need be modified for the elderly.' The SPC states no maximum daily dose. FORMULATION GAP: the fetched UK SPC covers the BUCCAL tablet only — it contains no oral tablet/syrup and no intramuscular posology, so the oral (5–10 mg three times daily) and IM (12.5 mg) regimens currently shown on this page are NOT supported by this source and need the corresponding UK SPCs. US labelling cross-check only (openFDA, Prochlorperazine Maleate tablets, Direct_Rx, 2025-01-22 — US labelling may differ from UK): 'To Control Severe Nausea and Vomiting: ... Oral Dosage-Tablets: Usually one 5mg or 10mg tablet 3 or 4 times daily. Daily dosages above 40 mgs should be used only in resistant cases.' PREGNANCY: the SPC gives no hyperemesis-gravidarum or pregnancy-specific dose — see pregnancyCategory below. PAEDIATRIC: the SPC states buccal tablets are not recommended in children under 12 years; no per-kg dose is given.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Impaired liver function
Existing blood dyscrasias
Epilepsy
Parkinson's disease
Prostatic hypertrophy
Narrow angle glaucoma

Side effects

Extrapyramidal reactions including acute dystonia, akathisia, parkinsonism and tardive dyskinesia (frequency not known)
Drowsiness, dizziness, convulsion (frequency not known)
Hypotension, usually orthostatic (frequency not known)
QT prolongation and arrhythmia (frequency not known); ventricular arrhythmias may result in ventricular fibrillation or cardiac arrest
Local effects: dry mouth, gum and mouth irritation, oral hypoaesthesia/paraesthesia, taste disorders (frequency not known)
Blood dyscrasia (rare); jaundice (rare); hyperprolactinaemia with gynaecomastia, galactorrhoea and amenorrhoea (very rare)

Clinical monograph

How it works

It blocks dopamine D2 receptors in the chemoreceptor trigger zone, suppressing the emetic reflex.

Prescribing in practice

Acute dystonic reactions and other extrapyramidal effects can occur, particularly in younger women, and warrant prompt recognition and treatment.
It is used when first-line antiemetics such as antihistamines fail to control nausea and vomiting of pregnancy; severe or refractory cases (hyperemesis gravidarum) need assessment for dehydration and ketosis.
It is sedating and can cause hypotension, and caution applies where other QT-prolonging or CNS-depressant drugs are co-prescribed.

Monitoring

Monitor for extrapyramidal symptoms, excessive sedation and postural blood pressure, and review hydration and weight in persistent pregnancy-related vomiting.

Counselling the patient

Report any muscle stiffness, abnormal eye movements or involuntary spasms of the face or neck straight away.
It may make you drowsy, so take care with tasks needing alertness.
Seek review if vomiting continues, you cannot keep fluids down, or you pass little urine.

Evidence & guidelines

UK guidance on nausea and vomiting in pregnancy positions phenothiazines such as prochlorperazine among the antiemetic options after first-line agents.

Reference: RCOG Green-top 69 (Hyperemesis Gravidarum 2024); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators