Drug interactions
Lisdexamfetamine + Promethazine
Severity: Moderate
Lisdexamfetamine 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 lisdexamfetamine is a stimulant, so each may partly blunt the other's effects. Phenothiazines can reduce the efficacy of amphetamines, and both drug classes can affect heart rate and rhythm, so cardiovascular effects deserve attention.
What this interaction means in plain words
Lisdexamfetamine 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.
Lisdexamfetamine belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Opposing CNS effects and dopamine receptor blockade by promethazine, with additive cardiovascular effects; not fully characterized.
What to do
Monitor for reduced stimulant effect, heart rate, blood pressure and palpitations. Consider an alternative to promethazine if the response to lisdexamfetamine is diminished.
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 Lisdexamfetamine
- Isocarboxazid + Lisdexamfetamine Contraindicated
- Linezolid + Lisdexamfetamine Contraindicated
- Lisdexamfetamine + Phenelzine Contraindicated
- Lisdexamfetamine + Procarbazine Contraindicated
- Lisdexamfetamine + Rasagiline Contraindicated
- Lisdexamfetamine + Safinamide Contraindicated
Frequently asked questions
Can I take Lisdexamfetamine with Promethazine?
MediHelp rates the interaction as moderate. Lisdexamfetamine 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 lisdexamfetamine is a stimulant, so each may partly blunt the other's effects. Phenothiazines can reduce the efficacy of amphetamines, and both drug classes can affect heart rate and rhythm, so cardiovascular effects deserve attention.
How serious is the interaction between Lisdexamfetamine 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 for reduced stimulant effect, heart rate, blood pressure and palpitations. Consider an alternative to promethazine if the response to lisdexamfetamine is diminished.
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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