Drug interactions
Ketamine + Promethazine
Severity: Moderate
Ketamine and Promethazine: moderate 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 is a sedating antihistamine and can add to the CNS depressant effects of ketamine, giving deeper or longer sedation and slower recovery. Respiratory depression and hypotension are possible, particularly at higher doses.
What this interaction means in plain words
Ketamine and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Ketamine belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Additive CNS depression through histamine H1 blockade and NMDA antagonism.
What to do
Titrate ketamine to effect and consider lower doses. Monitor sedation level, respiratory rate, oxygen saturation and blood pressure.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Ketamine
Frequently asked questions
Can I take Ketamine with Promethazine?
MediHelp rates the interaction as moderate. Ketamine and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Promethazine is a sedating antihistamine and can add to the CNS depressant effects of ketamine, giving deeper or longer sedation and slower recovery. Respiratory depression and hypotension are possible, particularly at higher doses.
How serious is the interaction between Ketamine and Promethazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Titrate ketamine to effect and consider lower doses. Monitor sedation level, respiratory rate, oxygen saturation and blood pressure.
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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