Methotrexateinteractions
methotrexate 25 MG/ML Injectable Solution
This is the interactions section of this product’s FDA label — what the manufacturer documented for this drug. It is not a check of your medication list, and a drug missing from it has not been cleared: licensed clinical databases list far more interactions than any single label does. Before combining medicines, ask a pharmacist, who can check everything you take at once and will do it for free.
Named on this label
Every name above is printed in the text below. This is not the full set of drugs that interact with this one — it is the set this manufacturer wrote down.
Drug interactions
Refer to full prescribing information for drug interactions with Methotrexate Injection.
7.1 Effects of
Other Drugs on Methotrexate Drugs that Increase Methotrexate Exposure Coadministration of methotrexate with the following products may increase methotrexate plasma concentrations, which may increase the risk of methotrexate severe adverse reactions. Increased organ specific adverse reactions may also occur when methotrexate is coadministered with hepatotoxic or nephrotoxic products. If coadministration cannot be avoided, monitor closely for methotrexate adverse reactions when coadministered with:
Penicillin or sulfonamide antibiotics
Highly protein bound drugs (e.g., oral anticoagulants, phenytoin, salicylates, sulfonamides, sulfonylureas, and tetracyclines)
Proton pump inhibitors
Probenecid
Antifolate drugs (e.g., dapsone, pemetrexed, pyrimethamine and sulfonamides)
Aspirin and other nonsteroidal anti-inflammatory drugs Unexpectedly severe and fatal gastrointestinal toxicity can occur with concomitant administration of methotrexate (primarily at high-dose) and nonsteroidal anti-inflammatory drugs (NSAIDs).
Mercaptopurine
Hepatotoxic products
Weak acids (e.g., salicylates)
Nephrotoxic products
Hematotoxic agents Nitrous Oxide Coadministration of methotrexate with nitrous oxide anesthesia potentiates the effect of methotrexate on folate-dependent metabolic pathways, which may increase the risk of severe methotrexate adverse reactions. Avoid nitrous oxide anesthesia in patients receiving methotrexate. Consider alternative therapies in patients who have received prior nitrous oxide anesthesia. Folic Acid Coadministration of methotrexate with folic acid or its derivatives decreases the clinical effectiveness of methotrexate in patients with neoplastic diseases. Methotrexate competes with reduced folates for active transport across cell membranes. Instruct patients to take folic or folinic acid only as directed by their healthcare provider.
7.2 Effects of
Methotrexate on Other Drugs Theophylline Coadministration of methotrexate with theophylline increases theophylline plasma concentrations which may increase the risk of theophylline adverse reactions. Monitor theophylline levels and adjust the theophylline dosage in accordance with approved product labeling.
Text above is quoted in full from the FDA-approved drug label published by openFDA, effective June 10, 2025. Matched to this product by RxNorm code. Cross-references to other sections of the full prescribing information have been removed, since they point to a document not shown here. Nothing else is changed: no sentence is shortened, reworded or summarised.
This page reproduces regulatory text for reference. It is not medical advice, and KenyRx is not a pharmacy or a prescriber. Talk to a doctor or pharmacist about whether a medicine is right for you.
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