Methotrexate is a prescription drug known as an antimetabolite. Doctors prescribe it for treating certain types of cancer and for some autoimmune disorders, including severe psoriasis, psoriatic arthritis and active rheumatoid arthritis. Caffeine may affect how well methotrexate works for rheumatoid arthritis patients, although research is inconclusive. Consult your doctor about your caffeine intake before you begin methotrexate therapy for any health problem.
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Methotrexate is useful for treating cancer because it slows the growth of cancer cells. In psoriasis patients, methotrexate slows the excessive growth of skin cells, which stops scaly patches from developing. Methotrexate also has anti-inflammatory effects that help with psoriatic and rheumatoid arthritis. In addition, the medicine reduces immune system activity, which can help patients with autoimmune disorders.
Interaction in Rheumatoid Arthritis
Drugs.com lists a moderate interaction between caffeine and methotrexate when taken by rheumatoid arthritis patients, noting that data is limited. The website cites one study in which patients who consumed more than 180 mg per day of caffeine while taking 7.5 mg per week of methotrexate for three months reported significantly lower improvement levels in their disease. Their morning stiffness and joint pain was greater than that of patients who consumed less caffeine. The 180 mg amount may be equal to about two cups of coffee, but that depends on how strongly you brew it.
A study published in the July 2006 issue of the "Journal of Rheumatology," however, did not find a similar negative effect of caffeine on methotrexate effectiveness for rheumatoid arthritis patients. In this group, no statistical difference occurred among groups with a low, moderate or high intake of caffeine. The groups with moderate and high caffeine intake did have a greater occurrence of swollen joints, although the occurrence was statistically insignificant.
Research published in the February 2007 issue of the "International Journal of Dermatology" also did not find a significant interaction of caffeine and methotrexate for patients with psoriasis and psoriatic arthritis. The authors mention previous animal and human research indicating that the effectiveness of methotrexate may be reduced in rheumatoid arthritis patients who consume caffeine. In this study, patients with psoriasis and psoriatic arthritis taking methotrexate were interviewed about their caffeine intake, and no association was found between the methotrexate dosage necessary for effectiveness and the amount of caffeine the patients consumed.