Promethazine

Pregnancy & gynaecology-specific. Every dose row is source-referenced; verify against institutional protocols.

PromethazineSedating antihistamine antiemetic

Regimens checked: 2026-10-17. Each indication has its own preparation, limits and safety checks.

Promethazine: indication-specific regimens
Indication	Dose	Route	Frequency	Duration / preparation	Maximum	Monitoring / cautions
First-line antihistamine option in RCOG HG guidance RCOG / BJOGchecked	12.5–25 mg	Oral	Every 4–8 hours as prescribed; use the lowest effective frequency	Review daily during acute illness; reduce/stop as symptoms and oral intake improve · Use oral tablets/liquid of a verified strength; 12.5 mg requires a suitable product rather than assuming every tablet can be split This row is ORAL. Injectable promethazine is not interchangeable and has separate tissue-injury/administration precautions.	The listed 25 mg every 4 h schedule totals 150 mg/day; this is a regimen bound, not a target, and sedation may require much less	Monitor Sedation, anticholinergic effects, oral intake and interactions with other sedatives/QT-prolonging drugs Contraindications / cautions Significant CNS/respiratory depression; avoid alcohol and additive sedation; do not drive when drowsy

Pregnancy safety

RCOG first-line NVP/HG option with sedation precautions

Lactation

Review repeated sedating doses, infant alertness and feeding