Drug interactions
Mercaptopurine + Smallpox vaccine live
Severity: Contraindicated
Mercaptopurine 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 generalized infection in immunosuppressed people. Mercaptopurine increases this risk and reduces the protective response.
What this interaction means in plain words
Mercaptopurine 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
Immunosuppression from a purine antimetabolite permits uncontrolled replication of vaccinia virus and impairs immune response.
What to do
Avoid live smallpox vaccine in patients on mercaptopurine except in a true exposure emergency under specialist guidance. A non-replicating alternative should be considered where available.
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 Mercaptopurine
- Adenovirus types 4 and 7 live + Mercaptopurine Contraindicated
- Azathioprine + Mercaptopurine Contraindicated
- Bcg vaccine live + Mercaptopurine Contraindicated
- Febuxostat + Mercaptopurine Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Mercaptopurine Contraindicated
- Adalimumab + Mercaptopurine Major
Frequently asked questions
Can I take Mercaptopurine with Smallpox vaccine live?
MediHelp rates the interaction as contraindicated. Mercaptopurine 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 generalized infection in immunosuppressed people. Mercaptopurine increases this risk and reduces the protective response.
How serious is the interaction between Mercaptopurine 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 on mercaptopurine except in a true exposure emergency under specialist guidance. A non-replicating alternative should be considered where available.
What other medicines interact with Mercaptopurine?
MediHelp also lists interactions of Mercaptopurine with, for example, Adenovirus types 4 and 7 live, Azathioprine, Bcg vaccine live. The full list is on the Mercaptopurine page.
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