Promethazine: Safety Considerations and Adverse Effects

Anticholinergic‑Sensitive Conditions

• Patients with prostatic hypertrophy have a markedly increased risk of urinary retention when treated with promethazine. 1
• Elevated intra‑ocular pressure is a contraindication for promethazine because its anticholinergic activity can precipitate acute angle‑closure events. 1

Neurological Risks in Vulnerable Populations

• Elderly individuals or those with pre‑existing cognitive impairment are more likely to experience worsening cognition, anticholinergic side effects, and falls when receiving promethazine. 1

Extrapyramidal Monitoring

• Promethazine can induce extrapyramidal symptoms such as dystonia, akathisia, restlessness, and oculogyric crises; clinicians should have diphenhydramine 25–50 mg readily available for prompt treatment. 2

Intravenous Administration Risks

• Extravasation or inadvertent intra‑arterial injection of promethazine may cause thrombophlebitis, tissue necrosis, and gangrene; the drug should be infused slowly (≤ 25 mg/min) and repeated or prolonged IV courses avoided. 1
• The same IV safety concerns are reiterated in additional Praxis guidance. 3