Methotrexate (MTX) is a medication used to modify the immune response. It treats various autoimmune diseases like rheumatoid arthritis, psoriasis, and Crohn’s disease, where an overactive immune system causes inflammation. It also treats certain cancers. Individuals taking methotrexate experience a lowered immune system. This helps manage underlying conditions but also introduces important health considerations.
How Methotrexate Interacts with the Immune System
Methotrexate primarily acts as an antimetabolite, interfering with rapidly dividing cells, including immune cells. It works by blocking the enzyme dihydrofolate reductase (DHFR), involved in tetrahydrofolate synthesis. Tetrahydrofolate is necessary for DNA, RNA, and protein production, essential for cell growth. By inhibiting DHFR, methotrexate reduces the synthesis of these components, particularly affecting immune cells like lymphocytes.
This interference reduces immune cell activity and proliferation, dampening the overall immune response. Methotrexate also modulates the immune system by increasing adenosine, a molecule with anti-inflammatory properties. This accumulation contributes to its immunosuppressive effects, reducing inflammation and immune cell activation.
Implications of Immune Suppression
A lowered immune system from methotrexate therapy increases susceptibility to infections. While serious infections are not common, individuals may experience a higher risk of infections. These can include bacterial infections, such as respiratory or skin infections, and viral infections like influenza or shingles. Fungal infections can also occur.
Individuals on methotrexate should be vigilant for signs of infection. Symptoms such as fever, chills, persistent cough, unusual fatigue, or new skin rashes warrant prompt medical attention. Recognizing these signs early allows for timely intervention, preventing more severe infections. Some studies indicate an increased risk of pneumonia in patients on methotrexate for rheumatoid arthritis.
Safeguarding Your Health While on Methotrexate
Proactive steps can mitigate risks associated with a lowered immune system while on methotrexate. Practicing good hygiene, like frequent handwashing, reduces exposure to germs. Avoiding close contact with sick individuals also helps prevent infection.
Discussing vaccinations with a healthcare provider is important. While methotrexate can reduce the effectiveness of some vaccines (e.g., influenza or pneumonia), certain vaccinations are still recommended for protection. Regular blood tests, including a complete blood count, monitor immune cell levels, liver, and kidney function, allowing for dose adjustments. Any unusual or concerning symptoms should be reported promptly to a healthcare provider.