SELECT AND USE MEDICATIONS
Immune-Modifying Medications and Vaccination
Immune-modifying medications can reduce damaging inflammation, control autoimmune disease, and prevent transplant rejection. Their effects on host defenses also change infection risk, vaccine response, and monitoring needs.
The degree of immunosuppression depends on the specific medication, dose, duration, combinations, underlying disease, and patient characteristics. “Immunosuppressed” is therefore insufficient as a stand-alone description of medication risk (Bruce, 2026; Gabardi et al., 2026).
Systemic Glucocorticoids
Glucocorticoids alter gene transcription and suppress multiple inflammatory pathways. They can rapidly reduce inflammation but also cause hyperglycemia, hypertension, mood and sleep disturbances, bone loss, adrenal suppression, and increased infection risk.
The clinical significance of steroid exposure differs between a brief course, prolonged systemic therapy, and local treatment. Evaluate cumulative exposure and concurrent immunosuppressants.
For live-vaccine decisions, the Centers for Disease Control and Prevention identifies systemic prednisone-equivalent treatment of at least 2 mg/kg/day or at least 20 mg/day for people weighing more than 10 kg, for at least 14 days as a commonly used threshold for substantially immunosuppressive dosing. Live vaccines are generally deferred for at least one month after such treatment ends. This threshold is specific to vaccination assessment and does not imply that lower exposure carries no infection risk (CDC, n.d.).
Methotrexate
Low-dose methotrexate has anti-inflammatory effects involving folate-dependent pathways and increased adenosine signaling. It is commonly used as a disease-modifying medication in rheumatoid arthritis.
For inflammatory disease, methotrexate is generally administered weekly. Daily administration in error can cause life-threatening toxicity. Prescribing and education should explicitly identify the weekly dose and administration day.
Monitor blood counts, liver tests, and kidney function. Important risks include marrow suppression, hepatotoxicity, mucositis, and pulmonary toxicity. Pregnancy is a major contraindication. Folic acid supplementation is commonly prescribed to reduce adverse effects.
Trimethoprim-sulfamethoxazole can substantially increase toxicity through overlapping antifolate and other effects. Medication reconciliation is essential before treating an infection (Bruce, 2026).
Azathioprine and Mycophenolate
Azathioprine is converted to thiopurine metabolites that interfere with purine metabolism. Mycophenolate inhibits inosine monophosphate dehydrogenase, reducing guanosine synthesis and lymphocyte proliferation.
Both can cause cytopenias, gastrointestinal effects, and infection. Mycophenolate has major embryo-fetal risks. Blood counts, organ function, reproductive considerations, and interacting medications require ongoing assessment.
Azathioprine has a clinically important interaction with xanthine oxidase inhibitors. Allopurinol coadministration requires a deliberately modified specialist regimen; routine full-dose combination can cause severe marrow toxicity (Gabardi et al., 2026).
Calcineurin Inhibitors
Tacrolimus and cyclosporine inhibit calcineurin-dependent T-cell activation and interleukin-2 transcription. They are central to many transplant regimens.
Monitoring includes drug concentrations, kidney function, blood pressure, electrolytes, and metabolic effects. Nephrotoxicity, neurotoxicity, hypertension, and infection are important concerns.
Clarithromycin, erythromycin, azole antifungals, and other inhibitors of relevant metabolic pathways can markedly increase tacrolimus or cyclosporine exposure. Azithromycin has less CYP3A inhibition but still warrants interaction review. Enzyme inducers can lower calcineurin-inhibitor exposure and threaten rejection control. Starting an antimicrobial in a transplant recipient requires coordination with the transplant team and a monitoring plan (Gabardi et al., 2026).
Biologic and Targeted Therapies
Tumor necrosis factor inhibitors reduce a cytokine pathway involved in inflammation and granuloma maintenance. Their use requires attention to tuberculosis and other serious infections.
Rituximab depletes CD20-positive B cells. Its effects can substantially reduce antibody responses to vaccination and increase hepatitis B reactivation risk.
Janus kinase inhibitors alter intracellular cytokine signaling. Monitoring includes blood counts, liver tests, lipids, and infection risk; thrombosis and other serious adverse outcomes also influence selection.
Screening and preventive plans should be medication-specific. Appropriate tuberculosis and hepatitis evaluation should precede relevant therapies rather than be postponed until infection develops (Bruce, 2026).
Coordinate Vaccination With Treatment
Review vaccination history before immunosuppressive therapy whenever feasible. Nonlive vaccines generally can be given during immunosuppression, although response may be reduced. Live vaccines may be unsafe during substantial immunosuppression.
B-cell-depleting treatment creates particular timing challenges because diminished vaccine response can persist after the last dose. Coordinate vaccination with the prescribing specialist. Do not apply a universal medication-holding interval across all therapies or vaccines (CDC, n.d.).
Clinical Follow-Up
A patient receiving immunosuppressive therapy may develop significant infection without a robust fever or inflammatory response. Assess new focal symptoms, physiologic changes, and functional decline.
The decision to interrupt treatment during infection must consider infection severity and the risk of disease flare or transplant rejection. Patients should know whom to contact before changing therapy.
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References
Bruce, S. P. (2026). Rheumatoid arthritis. In M. A. Chisholm-Burns, P. M. Malone, J. M. Kolesar, K. C. Lee, P. B. Bookstaver, & K. R. Matthias (Eds.), Pharmacotherapy principles & practice (7th ed.). McGraw Hill.
Centers for Disease Control and Prevention. (n.d.). Altered immunocompetence. Retrieved September 15, 2026, from https://www.cdc.gov/vaccines/hcp/imz-best-practices/altered-immunocompetence.html
Gabardi, S., Kim, M., & Olyaei, A. J. (2026). Solid organ transplantation. In M. A. Chisholm-Burns, P. M. Malone, J. M. Kolesar, K. C. Lee, P. B. Bookstaver, & K. R. Matthias (Eds.), Pharmacotherapy principles & practice (7th ed.). McGraw Hill.