Drug interactions
Leflunomide + Smallpox vaccine live
Severity: Contraindicated
Leflunomide and Smallpox vaccine live: contraindicated 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
Live vaccinia vaccine can cause progressive vaccinia and serious generalised infection in immunosuppressed patients. Leflunomide impairs the lymphocyte response needed to contain the virus. The vaccine response may also be inadequate.
What this interaction means in plain words
Leflunomide and Smallpox vaccine live are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Leflunomide's immunosuppression via dihydroorotate dehydrogenase inhibition permits uncontrolled replication of live vaccinia virus.
What to do
Avoid live smallpox vaccine in patients taking leflunomide unless the risk of exposure clearly outweighs the risk, with specialist input. Consider drug elimination before vaccination when the vaccine is essential.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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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
- Alefacept + Leflunomide Major
Frequently asked questions
Can I take Leflunomide with Smallpox vaccine live?
MediHelp rates the interaction as contraindicated. Leflunomide and Smallpox vaccine live are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Live vaccinia vaccine can cause progressive vaccinia and serious generalised infection in immunosuppressed patients. Leflunomide impairs the lymphocyte response needed to contain the virus. The vaccine response may also be inadequate.
How serious is the interaction between Leflunomide and Smallpox vaccine live?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid live smallpox vaccine in patients taking leflunomide unless the risk of exposure clearly outweighs the risk, with specialist input. Consider drug elimination before vaccination when the vaccine is essential.
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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