Is Folic Acid Safe with Methotrexate?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Do not take folic acid supplements without oncologist approval. If prescribed for toxicity reduction, use only the exact dose and timing specified by your care team — typically taken on non-methotrexate days.
Why this interaction occurs
Methotrexate works by inhibiting dihydrofolate reductase, blocking folate metabolism in cancer cells. Supplemental folic acid can compete with this mechanism and potentially reduce antitumor efficacy, though it is sometimes prescribed cautiously to mitigate mucositis and myelosuppression.
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 499,559 reports mentioning Methotrexate. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Methotrexate + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Folic Acid interactions → · All Methotrexate interactions →
Already checked this one — check your whole list
Educational only — not medical advice.
Always confirm with your doctor or pharmacist.