Drug interactions
Primaquine + Promethazine
Severity: Moderate
Primaquine 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
Both drugs have been associated with QT interval prolongation, so combined use may add to arrhythmia risk. The effect with primaquine is modest but relevant in patients with other risk factors.
What this interaction means in plain words
Primaquine 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.
Primaquine belongs to Anti Parasitic; Promethazine belongs to Respiratory.
Why it happens
Additive QT interval prolongation.
What to do
Obtain an ECG and correct potassium and magnesium if the patient has cardiac disease or other QT-prolonging drugs. Consider an alternative antiemetic if QT is prolonged.
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 Primaquine
- Pimozide + Primaquine Contraindicated
- Amiodarone + Primaquine Major
- Amisulpride + Primaquine Major
- Anagrelide + Primaquine Major
- Arsenic trioxide + Primaquine Major
- Asenapine + Primaquine Major
Frequently asked questions
Can I take Primaquine with Promethazine?
MediHelp rates the interaction as moderate. Primaquine 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. Both drugs have been associated with QT interval prolongation, so combined use may add to arrhythmia risk. The effect with primaquine is modest but relevant in patients with other risk factors.
How serious is the interaction between Primaquine 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: Obtain an ECG and correct potassium and magnesium if the patient has cardiac disease or other QT-prolonging drugs. Consider an alternative antiemetic if QT is prolonged.
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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