Preventing Infections in Non-Vaccinated Individuals on Methotrexate Therapy

Infection Risk and Prevention

Non-vaccinated individuals undergoing methotrexate therapy should receive prophylactic antiviral medication for herpes prevention and pneumocystis pneumonia prophylaxis, especially those with low immune cell counts or receiving high-dose corticosteroids 1, 2
Methotrexate is associated with an increased risk of infections, particularly pneumonia, skin/soft tissue infections, and urinary tract infections, with most infections occurring within the first 18 months of treatment 3
Opportunistic infections have been reported in patients taking methotrexate, usually within the first 12 weeks of treatment, but the risk remains throughout the treatment course 3

The British Journal of Dermatology recommends checking VZV serology if the patient has no history of chickenpox, and considering VZV vaccination for seronegative patients before starting methotrexate 4, 5
The Department of Health recommends stopping immunosuppressants for 6 months before administering the VZV vaccine 4
Screening for hepatitis B and C is recommended before initiating methotrexate therapy 6, 7

Prophylactic antiviral therapy, such as acyclovir or valacyclovir, is recommended for all patients receiving methotrexate, especially those with a history of herpes simplex virus or varicella zoster virus infection 1
Pneumocystis jirovecii pneumonia prophylaxis is strongly recommended when CD4 counts are low or the patient is receiving high-dose corticosteroids with methotrexate 1, 2, 7
Annual influenza vaccination is recommended for patients on methotrexate therapy 8

Complete blood count with differential should be monitored regularly, every 7-14 days for the first month and every 2-3 months once therapy is stabilized 8
Methotrexate should be temporarily discontinued during severe infection or when infection is not responding to standard treatment 3
Permanently discontinue methotrexate in patients who develop opportunistic infections 3

Fever is a potential symptom of methotrexate overdose, which may take 6-23 days to manifest alongside other symptoms like mucositis, diarrhea, and erythema, as noted by the British Journal of Dermatology 9
Chills and fever are listed as potential toxicities of methotrexate in dermatology guidelines, according to the American Academy of Dermatology 10

Fever in patients on methotrexate may indicate direct drug toxicity, as reported by the British Journal of Dermatology 9
Decreased resistance to infection is a known side effect of methotrexate, which can contribute to the development of fever, as stated by the American Academy of Dermatology 10

Checking complete blood count to assess for neutropenia or other cytopenias is recommended when fever develops in a patient on methotrexate, as suggested by the British Journal of Dermatology 11
Regular monitoring of complete blood count is recommended, every 2-4 weeks initially, then every 1-3 months on stable dosing, according to the American Academy of Dermatology 10
Patients should be educated to report symptoms of methotrexate toxicity, including fever, as advised by the British Journal of Dermatology 11