Drug interactions
Leflunomide + Tamoxifen
Severity: Minor
Leflunomide and Tamoxifen: minor 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
Teriflunomide, the active leflunomide metabolite, has been proposed to affect CYP2C9, but tamoxifen activation depends mainly on CYP2D6 and CYP3A4, so a meaningful loss of efficacy is not established. Both drugs can occasionally raise liver enzymes, so additive hepatotoxicity is the more practical concern.
What this interaction means in plain words
Leflunomide and Tamoxifen have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Leflunomide belongs to Musculoskeletal; Tamoxifen belongs to Endocrine.
Why it happens
A pharmacokinetic effect through CYP2C9 is theoretical; additive hepatotoxic potential is the more plausible concern.
What to do
No dose adjustment is needed. Monitor liver function tests periodically during combined therapy.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Leflunomide
- Bcg vaccine live + Leflunomide Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Leflunomide Contraindicated
- Leflunomide + Measles mumps and rubella vaccine live Contraindicated
- Leflunomide + Measles mumps rubella and varicella vaccine live Contraindicated
- Leflunomide + Measles vaccine Contraindicated
- Leflunomide + Smallpox vaccine live 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 Leflunomide with Tamoxifen?
MediHelp rates the interaction as minor. Leflunomide and Tamoxifen have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Teriflunomide, the active leflunomide metabolite, has been proposed to affect CYP2C9, but tamoxifen activation depends mainly on CYP2D6 and CYP3A4, so a meaningful loss of efficacy is not established. Both drugs can occasionally raise liver enzymes, so additive hepatotoxicity is the more practical concern.
How serious is the interaction between Leflunomide and Tamoxifen?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No dose adjustment is needed. Monitor liver function tests periodically during combined therapy.
What other medicines interact with Leflunomide?
MediHelp also lists interactions of Leflunomide with, for example, Bcg vaccine live, Influenza virus vaccine quadrivalent intranasal, Measles mumps and rubella vaccine live. The full list is on the Leflunomide page.
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