Is Folic Acid Needed With Methotrexate?

Methotrexate is a medication used in low weekly doses in the treatment of many autoimmune conditions, from rheumatoid arthritis to psoriasis to inflammatory bowel disease.  One way methotrexate works is by decreasing the production of folate.  For this reason, folic acid supplementation is used to offset possible adverse effects.  If too much folic acid is taken, it could decrease the effectiveness of methotrexate and if not enough is taken, there is a greater chance of nausea, mouth ulcers and changes in liver function tests. The amount suggested ranges from 5 mg a week up to 5mg everyday except the day methotrexate is taken. 

If you are experiencing adverse effects from methotrexate and are taking a low dose, you may wish to speak to your specialist about the way you take folic acid.  Another option is to use the prescription medication folinic acid instead of folic acid.  It is the “activated” form of folic acid and is more costly.  As up to 20% of patients cannot process folic acid into the active form, folinic acid can be a good alternative.  In people who make this conversion, folinic acid doesn’t offer better protection against adverse effects but in others it could make a difference.  It is generally taken as 5mg once weekly.

Stay tuned for next week’s blog when more strategies for reducing potential fatigue from methotrexate will be discussed…


Carolyn Whiskin is the Pharmacy Manager for Charlton Health.  Carolyn specializes in the treatment of autoimmune diseases, pharmaceutical compounding, women’s health, pain and smoking cessation. Carolyn has won provincial and national awards for her commitment to patient care and public service.

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