Looking Back: Managing the Adverse Effects of Methotrexate

A couple of weeks ago, we looked back on folic acid and methotrexate. At the end of that blog, we referenced today’s “Looking Back” blog, “Managing the Adverse Effects of Methotrexate.” In keeping with our series on some of our most popular blogs and those that we receive questions about regularly, we’re looking back on this one today!

Here is the original post…

Managing the Adverse Effects of Methotrexate

In our last blog, we looked at the role of folic acid and its importance when taking methotrexate. Even though folic acid reduces the adverse effects of methotrexate and is needed, it may fall short in managing the fatigue (or what some call their ‘sick day’) the day following their dose. Methotrexate is known to inadvertently stimulate a part of the brain referred to as the NMDA receptor. Dextromethorphan blocks this receptor and therefore can reduce the tiredness and foggy thinking that some people complain of after taking methotrexate.

An easy way to get the benefits of dextromethorphan, and combat this foggy thinking and fatigue is through taking DM Cough Syrup, which is readily available and can be purchased over the counter at any pharmacy. The suggested dose is two teaspoons twice daily the day before, day of, and day after taking methotrexate. While this tip is not commonly known, it was shared at past Ontario Rheumatology Association Conference by Dr. Jack Cush, a well respected American rheumatologist who uses this approach regularly.

Stay tuned to next week’s blog on options for methotrexate dosing…


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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