Drug interactions
Dextroamphetamine + Promethazine
Severity: Moderate
Dextroamphetamine 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 sedating while dextroamphetamine is a stimulant, so their clinical effects partly oppose each other and the net effect is unpredictable. Phenothiazines can also reduce amphetamine stimulant effects, and both drugs may contribute to tachycardia or arrhythmia in susceptible patients.
What this interaction means in plain words
Dextroamphetamine 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.
Dextroamphetamine belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Opposing CNS pharmacodynamic effects, with possible additive cardiac effects; no single established mechanism.
What to do
Monitor heart rate, blood pressure and therapeutic response, and avoid in patients with significant cardiac disease or QT risk. Adjust doses based on symptoms.
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
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Other interactions of Dextroamphetamine
- Dextroamphetamine + Isocarboxazid Contraindicated
- Dextroamphetamine + Linezolid Contraindicated
- Dextroamphetamine + Methylene blue Contraindicated
- Dextroamphetamine + Phenelzine Contraindicated
- Dextroamphetamine + Rasagiline Contraindicated
- Dextroamphetamine + Safinamide Contraindicated
Frequently asked questions
Can I take Dextroamphetamine with Promethazine?
MediHelp rates the interaction as moderate. Dextroamphetamine 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 sedating while dextroamphetamine is a stimulant, so their clinical effects partly oppose each other and the net effect is unpredictable. Phenothiazines can also reduce amphetamine stimulant effects, and both drugs may contribute to tachycardia or arrhythmia in susceptible patients.
How serious is the interaction between Dextroamphetamine 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: Monitor heart rate, blood pressure and therapeutic response, and avoid in patients with significant cardiac disease or QT risk. Adjust doses based on symptoms.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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