Drug interactions
Haloperidol + Tamoxifen
Severity: Moderate
Haloperidol 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
Haloperidol is a CYP2D6 substrate and inhibitor and may reduce conversion of tamoxifen to its active metabolite endoxifen. This could lessen tamoxifen's anticancer effect. Both drugs may also prolong the QT interval.
What this interaction means in plain words
Haloperidol 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.
Haloperidol belongs to Central Nervous System; Tamoxifen belongs to Endocrine.
Why it happens
Inhibition of CYP2D6-mediated activation of tamoxifen to endoxifen, plus additive QT effects.
What to do
Where possible choose an antipsychotic with little CYP2D6 inhibition in patients on tamoxifen for breast cancer. If combined, monitor the ECG and review the endocrine therapy plan with the oncologist.
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 Haloperidol
- Dofetilide + Haloperidol Contraindicated
- Dronedarone + Haloperidol Contraindicated
- Haloperidol + Ibutilide Contraindicated
- Haloperidol + Levoketoconazole Contraindicated
- Haloperidol + Panobinostat Contraindicated
- Haloperidol + 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 Haloperidol with Tamoxifen?
MediHelp rates the interaction as moderate. Haloperidol 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. Haloperidol is a CYP2D6 substrate and inhibitor and may reduce conversion of tamoxifen to its active metabolite endoxifen. This could lessen tamoxifen's anticancer effect. Both drugs may also prolong the QT interval.
How serious is the interaction between Haloperidol 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: Where possible choose an antipsychotic with little CYP2D6 inhibition in patients on tamoxifen for breast cancer. If combined, monitor the ECG and review the endocrine therapy plan with the oncologist.
What other medicines interact with Haloperidol?
MediHelp also lists interactions of Haloperidol with, for example, Dofetilide, Dronedarone, Ibutilide. The full list is on the Haloperidol page.
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