Phenothiazine (Antiemetic / Antivertigo) Pregnancy: There is inadequate evidence of safety in human pregnancy; should be avoided unless absolutely necessary during the first trimester. Neonates exposed to antipsychotics 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 (§4.6).

Prochlorperazine

Brand names: Stemetil, Buccastem (buccal)

Prochlorperazine is a phenothiazine used for nausea and vomiting and for vertigo, including in labyrinthine disorders such as Meniere's disease.

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

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

The fetched SPC is for Buccastem / Prochlorperazine 3 mg Buccal Tablets and states verbatim: 'Adults and children aged 12 years and over: One or two tablets twice a day.' The 3 mg strength is taken from the product name; confirm the strength of the product being prescribed. No explicit maximum daily dose is stated in the fetched §4.2 beyond the two-tablets-twice-daily regimen. Children under 12 years: not recommended (no per-kg paediatric dose is stated, so none is expressed here — verify any under-18 use against a children's formulary). Elderly patients: there is no evidence that dosage need be modified for the elderly, but they appear more susceptible to hypotension and neuromuscular reactions. Note this SPC covers only the buccal tablet presentation - oral tablet, IM and other prochlorperazine routes are NOT covered by the fetched source and must be sourced separately.

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.

US labelling (FDA)

Reference — US labelling, may differ from UK

(For children’s dosage and administration, see below.) Dosage should be increased more gradually in debilitated or emaciated patients. Elderly Patients: In general, dosages in the lower range are sufficient for most elderly patients. Since they appear to be more susceptible to hypotension and neuromuscular reactions, such patients should be observed closely. Dosage should be tailored to the individual, response carefully monitored and dosage adjusted accordingly. Dosage should be increased more gradually in elderly patients. 1.To Control Severe Nausea and Vomiting: Adjust dosage to the response of the individual. Begin with the lowest recommended dosage. Oral Dosage-Tablets: Usually one …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-01-22. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

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 - particularly in elderly or volume-depleted patients
QT prolongation and arrhythmia, including ventricular arrhythmias which may result in ventricular fibrillation or cardiac arrest
Local buccal effects - dry mouth, gum and mouth irritation, oral hypoaesthesia and paraesthesia, taste disorders
Blood dyscrasia (rare); hyperprolactinaemia causing gynaecomastia, galactorrhoea and amenorrhoea (very rare); jaundice (rare); photosensitivity

Interactions

Concomitant QT interval-prolonging drugs: neuroleptic phenothiazines may potentiate QT prolongation, increasing the risk of torsade de pointes - use with caution (stated in §4.4 of the fetched extract, which cross-refers to §4.5; the full §4.5 interactions section was NOT captured in the bundle - clinician to source it)

Clinical monograph

How it works

It blocks dopamine D2 receptors (centrally, including the chemoreceptor trigger zone), reducing nausea and vertigo.

Prescribing in practice

Extrapyramidal effects, especially acute dystonia in younger people, can occur — use with care and for the shortest time.
Avoid using it to mask the cause of undiagnosed vomiting, particularly in children and young adults.
It can prolong the QT interval and cause sedation and postural hypotension.

Monitoring

Review for movement disorders and the ongoing need.

Counselling the patient

Report muscle spasms (especially of the face or neck), restlessness or abnormal movements.
It can cause drowsiness.

Evidence & guidelines

Used for nausea, vomiting and vertigo, with caution about extrapyramidal effects.

Reference: 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

Pathways