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Phenothiazine Antiemetic / Antipsychotic Pregnancy: UK SPC §4.6, verbatim: 'There is inadequate evidence of the safety in human pregnancy. Buccastem/Prochlorperazine 3 mg Buccal Tablets should be avoided unless absolutely necessary during the first trimester of pregnancy. Since data from animal studies show that prochlorperazine may be found in breast milk it should not be used during lactation. Neonates exposed to antipsychotics (including prochlorperazine) during the third trimester of pregnancy are at risk of adverse reactions including extrapyramidal and/or withdrawal symptoms that may vary in severity and duration following delivery. There have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, or feeding disorder. Consequently, newborns should be monitored carefully.' The US label adds that if extrapyramidal symptoms occur in pregnant patients 'the drug should be stopped and not reinstituted'.

Prochlorperazine

Brand names: Stemetil, Buccastem (buccal)

Prochlorperazine is a phenothiazine antiemetic used for nausea, vomiting and vertigo (including labyrinthine causes); this page covers its use in older people, in whom adverse effects are more likely.

Adult dose

Dose: Severe nausea and vomiting — oral (US label): one 5 mg or 10 mg tablet three or four times daily, using the lower end of the range in older patients. Buccal (UK SPC, 3 mg buccal tablets): one or two tablets, i.e. 3-6 mg, twice a day.
Route: Oral (5 mg or 10 mg tablets — US label) and buccal (3 mg buccal tablets — UK SPC). Buccal method, UK SPC §4.2 verbatim: 'To be placed in the buccal cavity, high up along the top gum under the upper lip, until dissolved. Do not chew or swallow the tablet.' The intramuscular route the current page also lists is not covered by any label in this bundle, so no IM dose is published here.
Frequency: Oral: three or four times daily. Buccal: twice a day.
Max: No maximum dose is stated for nausea and vomiting in either label; see the notes for the resistant-case wording the US label uses and for the psychiatric-indication ceilings, which must not be applied to this page.
SCOPE — this record publishes the page's primary indication (antiemetic use for severe nausea and vomiting) by its two sourced routes, oral and buccal, with the labels' own elderly qualifiers. || THE TWO LABELS SAY DIFFERENT THINGS ABOUT AGE, AND BOTH ARE GIVEN VERBATIM. UK SPC §4.2: 'Elderly patients: There is no evidence that dosage need be modified for the elderly.' US label: '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.' The US label adds: 'Dosage should be increased more gradually in debilitated or emaciated patients.' || The US label's exact words are 'Daily dosages above 40 mgs should be used only in resistant cases' — a resistant-case threshold, not a ceiling. The label's true ceilings belong to psychiatric indications (non-psychotic anxiety: 'Do not administer in doses of more than 20mg per day or for longer than 12 weeks') and must not be transferred to this antiemetic page. || DEMENTIA AND STROKE RISK, UK SPC §4.4 verbatim: elderly people with dementia treated with antipsychotics 'are at a small increased risk of death compared with those who are not treated'; the product 'is not licensed for the treatment of dementia-related behavioural disturbances'; and it 'should be avoided in patients with stroke risk factors and myasthenia gravis'. || FALLS/HYPOTENSION, UK SPC §4.4: 'Hypotension, usually postural, may occur, particularly in elderly or volume depleted patients.' || PROVENANCE WARNING: the oral figures are US labelling; no UK SPC for oral prochlorperazine was fetched. The buccal figures are UK SPC, and 3 mg is a buccal-only strength.

Dose adjustments

Renal

Not stated — no renal-impairment dosing statement appears in any fetched section of either label.

Hepatic

No dose adjustment is given, because impaired liver function is a CONTRAINDICATION in the UK SPC: §4.3 lists 'Impaired liver function'. US label: 'Cholestatic jaundice has occurred. If fever with grippe-like symptoms occurs, appropriate liver studies should be conducted. If tests indicate an abnormality, stop treatment.'

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients (UK SPC §4.3); the US label gives this as 'known hypersensitivity to phenothiazines'
  • Impaired liver function (UK SPC §4.3)
  • Existing blood dyscrasias (UK SPC §4.3)
  • Epilepsy (UK SPC §4.3)
  • Parkinson's Disease (UK SPC §4.3)
  • Prostatic hypertrophy (UK SPC §4.3)
  • Narrow angle glaucoma (UK SPC §4.3)
  • Comatose states, or the presence of large amounts of central nervous system depressants (alcohol, barbiturates, narcotics) — US label, Contraindications
  • Paediatric surgery; paediatric patients under 2 years of age or under 20 lbs; children in conditions for which a dosage has not been established — US label, Contraindications
  • Not a contraindication but an avoidance (UK SPC §4.4): 'should be avoided in patients with stroke risk factors and myasthenia gravis'

Side effects

  • Extrapyramidal reactions including acute dystonia, akathisia, parkinsonism and tardive dyskinesia (UK SPC §4.8, frequency 'Not known'). §4.4 adds that patients with AIDS 'may be particularly susceptible to antipsychotic-induced extrapyramidal effects'
  • Drowsiness, dizziness, convulsion (UK SPC §4.8, not known); insomnia and agitation (UK SPC §4.8, not known). US label: drowsiness, dizziness, blurred vision
  • Hypotension, usually orthostatic (UK SPC §4.8). §4.4: 'Hypotension, usually postural, may occur, particularly in elderly or volume depleted patients'
  • QT prolongation and arrhythmia (UK SPC §4.8, not known). §4.4: neuroleptic phenothiazines 'may potentiate QT interval prolongation which increases the risk of onset of serious ventricular arrhythmias of the torsade de pointes type, which is potentially fatal'; ventricular arrhythmias may result in ventricular fibrillation or cardiac arrest
  • Local effects of the buccal route: dry mouth, gum irritation, mouth irritation, oral hypoaesthesia, oral paraesthesia, taste disorders (UK SPC §4.8)
  • Blood dyscrasia (UK SPC §4.8, rare); agranulocytosis is a phenothiazine class effect (§4.4/§4.8). US label: 'Leukopenia and agranulocytosis have occurred'
  • Jaundice (UK SPC §4.8, rare) and cholestasis (not known); the US label reports cholestatic jaundice
  • Hyperprolactinaemia which may result in gynaecomastia, galactorrhoea and amenorrhoea (UK SPC §4.8, very rare); the US label lists amenorrhoea
  • Hyponatraemia, syndrome of inappropriate antidiuretic hormone secretion, hyperglycaemia, impaired glucose tolerance (UK SPC §4.8, not known)
  • Skin reaction and photosensitivity (UK SPC §4.8) — §4.4 advises avoiding direct sunlight and using sunscreen
  • Hypersensitivity reactions such as rash and angioedema (UK SPC §4.8, not known)
  • Neuroleptic malignant syndrome (UK SPC §4.4): 'a potentially fatal symptom complex... characterised by unexplained fever, hyperthermia, autonomic dysfunction, altered consciousness, muscle rigidity. It is imperative that treatment be discontinued in the event of NMS'
  • Venous thromboembolism, including pulmonary embolism and deep vein thrombosis, reported with antipsychotic drugs (UK SPC §4.4/§4.8, frequency unknown)
  • Neonatal drug withdrawal syndrome (UK SPC §4.8, not known — see pregnancy)
  • Impotence, ejaculation disorder and priapism — phenothiazine class effects (UK SPC §4.8)

Monitoring

  • UK SPC §4.4: 'The occurrence of unexplained infections or fever may be evidence of blood dyscrasia (see section 4.8), and requires immediate haematological investigation.' US label: warn patients to report the sudden appearance of sore throat or other signs of infection; 'If white blood cell and differential counts indicate leukocyte depression, stop treatment'
  • UK SPC §4.4: 'If signs of cardiac arrhythmia occur during treatment... treatment should be stopped and an ECG should be performed.' Use with caution where QT risk factors are present — cardiac disease (heart failure, myocardial infarction), bradycardia (< 50 bpm), a history of ventricular dysrhythmias, uncorrected hypokalaemia and/or hypomagnesaemia, and concomitant QT-prolonging drugs
  • UK SPC §4.4: identify all possible risk factors for venous thromboembolism before and during treatment and undertake preventive measures
  • UK SPC §4.4: watch for neuroleptic malignant syndrome — unexplained fever, hyperthermia, autonomic dysfunction, altered consciousness, muscle rigidity — and discontinue immediately if it occurs
  • Postural blood pressure, particularly in elderly or volume-depleted patients (UK SPC §4.4)
  • US label: 'If fever with grippe-like symptoms occurs, appropriate liver studies should be conducted. If tests indicate an abnormality, stop treatment'
  • Watch for extrapyramidal reactions and reduce or stop the dose accordingly; the US label instructs that if they occur in children or pregnant patients 'the drug should be stopped and not reinstituted'
  • UK SPC §4.4: nausea and vomiting as a sign of organic disease may be masked by the anti-emetic action — re-assess the underlying cause
  • This is a geriatrics page: the US label's instruction that elderly patients 'appear to be more susceptible to hypotension and neuromuscular reactions' and 'should be observed closely' is the bundle's own elderly-specific monitoring rule

Clinical monograph

How it works

It blocks dopamine D2 receptors, including those in the chemoreceptor trigger zone, producing antiemetic and antivertigo effects.

Prescribing in practice

  • In older people it carries a high risk of extrapyramidal effects, parkinsonism and falls, and antipsychotics are associated with increased stroke and mortality risk in those with dementia, so use the lowest effective dose for the shortest time.
  • It can prolong the QT interval and cause postural hypotension and sedation; review concurrent QT-prolonging and CNS-depressant drugs.
  • Avoid in Parkinson's disease and dementia with Lewy bodies, where it can markedly worsen motor and cognitive symptoms.

Monitoring

Monitor older patients for extrapyramidal symptoms, drowsiness, postural blood pressure and the continued need for treatment.

Counselling the patient

  • It can cause drowsiness and dizziness, especially on standing.
  • Report abnormal movements, stiffness or restlessness promptly.

Evidence & guidelines

MHRA warnings on antipsychotics in dementia and general geriatric guidance support cautious, short-term use of prochlorperazine in older adults.

Reference: STOPP/START v3; AGS Beers Criteria 2023; 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).

Related

Curated clinical cross-links plus same-class fallbacks.

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