Chlorpromazine and Promethazine: interaction and safety
This source-based reference is not a personal treatment recommendation. The relevance and management of an interaction depend on the exact products, route, dose and clinical situation.
Interaction mechanism
Systemic QT-prolonging effects may add; low potassium and a slow heart rate increase concern. Additive central nervous system effects may worsen alertness and balance. Antimuscarinic effects may add.
Clinical significance and safety
Chlorpromazine and Promethazine: Systemic QT-prolonging effects may add; low potassium and a slow heart rate increase concern. Additive central nervous system effects may worsen alertness and balance. Antimuscarinic effects may add. Drowsiness, dizziness, reduced coordination and falls can be more likely. Driving and other hazardous tasks require particular caution when affected. The class warning does not mean that every combination is contraindicated or that each pair has been tested in a separate clinical trial. Heart disease, a slow pulse and low potassium or magnesium can increase concern. A clinician determines whether ECG or electrolyte checks are needed. Fainting or new irregular palpitations require urgent assessment. Dry mouth, blurred vision, constipation, urinary retention, overheating or confusion may increase. Older adults and people with glaucoma or bowel or bladder obstruction are particularly vulnerable. Severe abdominal distension, inability to urinate or a painful red eye needs prompt assessment.
Using this information
This is a source-based reference record, not a recommendation to combine, stop or change medicines. A missing interaction record does not establish safe use. A qualified healthcare professional should consider the exact products, doses, other medicines and individual health circumstances.