Drug interactions
Methyldopa + Promethazine
Severity: Minor
Methyldopa and Promethazine: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Promethazine causes sedation and can contribute to hypotension, which may add to the sedative and blood pressure effects of methyldopa. The legacy claim of pharmacodynamic antagonism is not well supported, and the combination is not a true contraindication.
What this interaction means in plain words
Methyldopa and Promethazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Methyldopa belongs to Cardiovascular; Promethazine belongs to Respiratory.
Why it happens
Additive central nervous system depression and mild hypotensive effects; no firm antagonism mechanism is established.
What to do
No routine change is needed. Counsel the patient about drowsiness and monitor blood pressure when starting promethazine.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Other interactions of Methyldopa
- Methyldopa + Tranylcypromine Contraindicated
- Iobenguane i + Methyldopa Major
- Lofexidine + Methyldopa Major
- Methyldopa + Pexidartinib Major
- Methyldopa + Pretomanid Major
- Methyldopa + Thioridazine Major
Frequently asked questions
Can I take Methyldopa with Promethazine?
MediHelp rates the interaction as minor. Methyldopa and Promethazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Promethazine causes sedation and can contribute to hypotension, which may add to the sedative and blood pressure effects of methyldopa. The legacy claim of pharmacodynamic antagonism is not well supported, and the combination is not a true contraindication.
How serious is the interaction between Methyldopa and Promethazine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine change is needed. Counsel the patient about drowsiness and monitor blood pressure when starting promethazine.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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