Can i take b12 with methotrexate?

Short answer: Yes—taking vitamin B12 while on methotrexate is generally safe and often recommended if you’re at risk for or have a confirmed B12 deficiency. It does not interfere with methotrexate’s action and is not a substitute for the folate (folinic acid/folic acid) support that is routinely given to help reduce methotrexate toxicity.

Why you might want B12

How B12 and methotrexate interact (or don’t)

• Pharmacologically: Methotrexate is a folate antagonist (it blocks dihydrofolate reductase). Vitamin B12 (cobalamin) is part of a different metabolic pathway (the conversion of homocysteine to methionine) and does not counteract methotrexate’s therapeutic or toxic effects.
• Side‑effects: There’s no evidence that B12 reduces methotrexate’s efficacy or increases its toxicity. In fact, B12 is often given to patients with deficiencies that might otherwise exacerbate side‑effects.
• Folate support: The standard practice is to give folinic acid (leucovorin) or folic acid to “rescue” cells from methotrexate’s folate‑blocking effects. B12 does not replace this; they serve complementary roles.

Practical tips

Bottom line

• It’s safe to take vitamin B12 while on methotrexate.
• It doesn’t replace the folate (folinic acid/folic acid) rescue that is often necessary to mitigate methotrexate toxicity.
• Check with your healthcare team before starting any new supplement, especially if you have kidney disease, a history of blood disorders, or other medications that may interact.

If you’re feeling unwell or notice new symptoms while on methotrexate, always reach out to your doctor or pharmacist promptly.