Drug interactions
Mefloquine + Tamoxifen
Severity: Moderate
Mefloquine and Tamoxifen: 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
Tamoxifen has a modest QT-prolonging effect and mefloquine can also lengthen the QT interval. The combination may increase the risk of arrhythmia, particularly in patients with other risk factors.
What this interaction means in plain words
Mefloquine and Tamoxifen 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.
Mefloquine belongs to Anti Parasitic; Tamoxifen belongs to Endocrine.
Why it happens
Additive prolongation of cardiac repolarization (pharmacodynamic).
What to do
Obtain a baseline ECG and correct electrolyte abnormalities. Prefer a non-QT-prolonging antimalarial if the patient has other risk factors.
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 Mefloquine
- Arsenic trioxide + Mefloquine Contraindicated
- Dronedarone + Mefloquine Contraindicated
- Ibutilide + Mefloquine Contraindicated
- Levoketoconazole + Mefloquine Contraindicated
- Mefloquine + Nilotinib Contraindicated
- Mefloquine + Pimozide Contraindicated
Other interactions of Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
Frequently asked questions
Can I take Mefloquine with Tamoxifen?
MediHelp rates the interaction as moderate. Mefloquine and Tamoxifen 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. Tamoxifen has a modest QT-prolonging effect and mefloquine can also lengthen the QT interval. The combination may increase the risk of arrhythmia, particularly in patients with other risk factors.
How serious is the interaction between Mefloquine and Tamoxifen?
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 a baseline ECG and correct electrolyte abnormalities. Prefer a non-QT-prolonging antimalarial if the patient has other risk factors.
What other medicines interact with Mefloquine?
MediHelp also lists interactions of Mefloquine with, for example, Arsenic trioxide, Dronedarone, Ibutilide. The full list is on the Mefloquine page.
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