Co Trimoxazole and Methotrexate: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Co Trimoxazole and Methotrexate unless specifically directed by your doctor.
How Co Trimoxazole interacts with Methotrexate
Trimethoprim and methotrexate both inhibit folate metabolism, while sulfamethoxazole may reduce renal methotrexate clearance and displace it from protein binding.
What you should do
Avoid the combination because severe pancytopenia and mucositis can occur. Choose a non-antifolate antimicrobial.
Key facts
Severity
Major — avoid combination
Mechanism
Trimethoprim and methotrexate both inhibit folate metabolism, while sulfamethoxazole may reduce renal methotrexate clear...
Action
Avoid the combination because severe pancytopenia and mucositis can occur. Choose a non-antifolate antimicrobial.
Frequently asked questions
Can I take Co Trimoxazole and Methotrexate together?
No — this combination should generally be avoided. Avoid the combination because severe pancytopenia and mucositis can occur. Choose a non-antifolate antimicrobial.
What is the severity of this interaction?
The interaction between Co Trimoxazole and Methotrexate is classified as Major — avoid combination. Trimethoprim and methotrexate both inhibit folate metabolism, while sulfamethoxazole may reduce renal methotrexate clearance and displace it from protein binding.
What should I do if I'm prescribed both?
Avoid the combination because severe pancytopenia and mucositis can occur. Choose a non-antifolate antimicrobial. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.