Drug interactions
Methotrexate + Sulfadiazine
Severity: Major
Methotrexate and Sulfadiazine: major interaction.
Last updated Sources: US FDA label
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
Sulfonamides can raise methotrexate levels and add to its antifolate effect, which may cause severe myelosuppression and pancytopenia. Both agents are also nephrotoxic or renally cleared.
What this interaction means in plain words
Methotrexate and Sulfadiazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Sulfonamides displace methotrexate from albumin and reduce its renal tubular secretion, and also add antifolate effects.
What to do
Avoid the combination, particularly with higher methotrexate doses. If it cannot be avoided, monitor blood counts and renal function closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Methotrexate
- Acitretin + Methotrexate Contraindicated
- Adenovirus types 4 and 7 live + Methotrexate Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Methotrexate Contraindicated
- Ketorolac + Methotrexate Contraindicated
- Measles mumps and rubella vaccine live + Methotrexate Contraindicated
- Measles mumps and rubella vaccine + Methotrexate Contraindicated
Frequently asked questions
Can I take Methotrexate with Sulfadiazine?
MediHelp rates the interaction as major. Methotrexate and Sulfadiazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Sulfonamides can raise methotrexate levels and add to its antifolate effect, which may cause severe myelosuppression and pancytopenia. Both agents are also nephrotoxic or renally cleared.
How serious is the interaction between Methotrexate and Sulfadiazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination, particularly with higher methotrexate doses. If it cannot be avoided, monitor blood counts and renal function closely.
What other medicines interact with Methotrexate?
MediHelp also lists interactions of Methotrexate with, for example, Acitretin, Adenovirus types 4 and 7 live, Influenza virus vaccine quadrivalent intranasal. The full list is on the Methotrexate page.
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