Drug interactions
Leflunomide + Sulfamethoxazole
Severity: Minor
Leflunomide and Sulfamethoxazole: 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 weakly inhibits CYP2C9, the main enzyme clearing the sulfamethoxazole component, so sulfamethoxazole levels might rise slightly. The expected clinical consequence is small. Both drugs can cause liver and bone marrow toxicity, which is a more relevant concern.
What this interaction means in plain words
Leflunomide and Sulfamethoxazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Weak CYP2C9 inhibition by teriflunomide may slightly reduce sulfamethoxazole clearance.
What to do
No dose change is usually required. Monitor blood counts and liver enzymes if used together for extended periods.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Leflunomide and Sulfamethoxazole, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
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
Frequently asked questions
Can I take Leflunomide with Sulfamethoxazole?
MediHelp rates the interaction as minor. Leflunomide and Sulfamethoxazole 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 weakly inhibits CYP2C9, the main enzyme clearing the sulfamethoxazole component, so sulfamethoxazole levels might rise slightly. The expected clinical consequence is small. Both drugs can cause liver and bone marrow toxicity, which is a more relevant concern.
How serious is the interaction between Leflunomide and Sulfamethoxazole?
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 change is usually required. Monitor blood counts and liver enzymes if used together for extended periods.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
