Understanding Methotrexate and Infection Risk
Methotrexate (MTX) is a cornerstone disease-modifying antirheumatic drug (DMARD) used to treat various autoimmune conditions, including rheumatoid arthritis and psoriasis [1.7.4]. It works by modulating the immune system to reduce inflammation. However, this immune modulation can also lower the body's ability to fight infections [1.7.1]. Consequently, developing an infection while on methotrexate often requires temporarily stopping the medication to allow the immune system to effectively combat the pathogen [1.7.3]. The critical question for both patients and clinicians is determining the right moment to resume treatment.
General Principles for Restarting Methotrexate
The consensus across multiple health guidelines is that methotrexate should be withheld during an active infection, especially one that requires antibiotic treatment [1.2.3, 1.4.3]. The primary rule is to wait until the patient is clinically improving, symptoms have resolved, and the full course of prescribed antibiotics has been completed [1.2.2, 1.2.6]. Restarting too early can impede recovery, while waiting too long can risk a flare-up of the underlying autoimmune condition [1.4.4].
Key Factors Influencing the Decision
Several factors must be considered by a healthcare provider before advising a patient to restart methotrexate:
- Severity of the Infection: The distinction between a minor and a serious infection is paramount. For minor infections like an uncomplicated urinary tract infection (UTI) or a common cold, some clinicians may advise continuing methotrexate, while others prefer a brief pause [1.4.3, 1.5.6]. However, for any serious infection requiring antibiotics, stopping MTX is the standard recommendation [1.4.3].
- Type of Infection: Certain infections warrant specific protocols. For example, if a patient develops shingles (Herpes Zoster), methotrexate should be stopped, and antiviral treatment initiated [1.2.4]. Contact with chickenpox may also require temporarily stopping the drug [1.2.5].
- Completion of Antibiotics: It is consistently recommended to finish the entire course of antibiotics before restarting methotrexate [1.2.6, 1.4.5]. This ensures the infection is fully eradicated.
- Patient's Overall Health: The patient's general well-being is a key indicator. The common advice is to restart methotrexate only when the patient "feels better" or is "restored to good health" [1.2.1, 1.6.4]. This subjective measure, combined with objective clinical improvement, guides the decision.
- Interacting Medications: The choice of antibiotic matters. Some antibiotics, like trimethoprim and co-trimoxazole, can interact with methotrexate and increase the risk of toxicity, making it even more crucial to pause the MTX [1.6.6].
Restarting Methotrexate: A Comparison by Infection Type
| Infection Type | General Guideline for Holding MTX | Criteria to Restart Methotrexate |
|---|---|---|
| Upper Respiratory Infection (e.g., common cold) | Discretionary. Some doctors advise continuing for minor colds, others recommend holding if symptoms are significant or could progress [1.5.5, 1.5.6]. | When symptoms have resolved. If antibiotics were needed, after the course is complete [1.2.3]. |
| Urinary Tract Infection (UTI) | Usually continued for uncomplicated UTIs, but held for symptomatic or complicated cases requiring antibiotics [1.4.3, 1.8.2]. | After antibiotic course is complete and symptoms have cleared. One source suggests resuming 1 week after being restored to health [1.8.2]. |
| Skin Infection (e.g., cellulitis) | Hold methotrexate during the active infection and while on antibiotic therapy [1.7.6]. | After the full course of antibiotics is finished and the infection shows significant clinical improvement [1.2.4]. |
| Serious Systemic Infection (e.g., pneumonia, sepsis) | Always discontinue methotrexate immediately [1.2.4, 1.7.3]. | Only after the infection has fully resolved, the antibiotic course is complete, and the patient has made a significant clinical recovery, as judged by a physician [1.2.4]. |
| Shingles (Herpes Zoster) | Stop methotrexate immediately and begin antiviral medication [1.2.4, 1.2.5]. | After the infection has resolved and upon the advice of a healthcare provider [1.2.5]. |
The Role of the Healthcare Provider
The decision of when to restart methotrexate after an infection should never be made by the patient alone. It is essential to communicate with your rheumatologist or prescribing doctor [1.7.1]. They will assess the severity of the infection, consider your overall health status, and provide personalized instructions. Upon restarting, the same monitoring schedule for blood tests should typically be followed to check for any effects on blood counts or liver function [1.2.4].
Authoritative Link: American College of Rheumatology - Methotrexate Patient Information
Conclusion
Navigating an infection while on methotrexate requires a careful balance between managing your autoimmune disease and allowing your body to heal. The standard protocol is to temporarily stop methotrexate, particularly for moderate-to-severe infections requiring antibiotics. The medication is generally restarted once the infection has resolved, the antibiotic course is complete, and you feel clinically well again [1.2.2, 1.4.3]. Always consult with your healthcare provider for guidance tailored to your specific situation to ensure a safe and effective return to your treatment regimen.
