Should I stop iguratimod during an active herpes simplex or varicella‑zoster virus infection and only restart it after the infection is fully resolved with antiviral therapy?

Management of Iguratimod During Active Herpes Virus Infections

Primary Recommendation

For active herpes simplex virus (HSV) or varicella-zoster virus (VZV) infections in patients taking iguratimod, discontinue the immunomodulator immediately and initiate appropriate antiviral therapy; restart iguratimod only after complete clinical resolution with all vesicular lesions crusted and fever resolved. 1

Treatment Algorithm Based on Infection Severity

Superficial/Uncomplicated HSV Infection

• Continue antiviral therapy with oral acyclovir, valacyclovir, or famciclovir until all lesions have completely resolved 1
• Iguratimod can remain on hold during this period without requiring discontinuation for mild, localized disease 1
• Restart iguratimod after lesion resolution is complete 1

Severe or Systemic HSV Disease

• Immediately discontinue iguratimod until symptoms improve 1
• Initiate intravenous acyclovir and continue until clinical response is achieved 1
• Switch to oral antiviral (acyclovir, valacyclovir, or famciclovir) to complete 14-21 days total treatment 1
• Restart iguratimod only after complete symptom resolution and careful multidisciplinary consideration 1

Uncomplicated Varicella Zoster (Shingles)

• Do not commence or continue iguratimod during active chickenpox or herpes zoster infection 1
• Initiate oral antiviral therapy promptly with valacyclovir or acyclovir 1, 2
• Restart iguratimod after all vesicles have crusted over and fever has resolved 1

Disseminated or Invasive VZV Infection

• Immediately discontinue iguratimod if clinically feasible 1, 2
• Initiate intravenous acyclovir 5-10 mg/kg every 8 hours 1, 2, 3
• Continue IV therapy at least until all lesions have scabbed 1, 2
• Temporary reduction in immunosuppression is strongly recommended to reduce mortality 1
• Restart iguratimod only after skin vesicles have completely resolved and patient has commenced anti-VZV therapy 1

Critical Clinical Distinctions

The severity of herpes virus infections determines management strategy. Mild, localized HSV (oral or genital herpes) may not require iguratimod discontinuation, whereas systemic HSV disease (encephalitis, esophagitis, colitis) mandates immediate cessation of all immunosuppressants. 1 This distinction is crucial because systemic CMV reactivation causing organ involvement is associated with poor outcomes, and prompt antiviral treatment with discontinuation of immunosuppressive agents is associated with clinical improvement and decreased mortality. 1

For VZV infections, the threshold is lower: immunomodulator therapy should not be commenced during active infection with chickenpox or herpes zoster at all. 1 This reflects the higher risk of dissemination and complications in immunocompromised patients, where five of 20 cases of varicella proved fatal in one IBD review. 1

Monitoring During Active Infection

• Assess for dissemination including multi-dermatomal involvement, visceral organ involvement (hepatitis, pneumonia, encephalitis), or CNS complications 1, 2
• Monitor renal function if using IV acyclovir, with dose adjustments for creatinine clearance 2, 4
• Watch for treatment failure after 7-10 days, which may indicate acyclovir resistance requiring foscarnet 2, 5

Common Pitfalls to Avoid

Do not restart iguratimod prematurely before complete lesion crusting and fever resolution, as this increases risk of disseminated disease and mortality. 1 The guideline evidence consistently emphasizes that immunosuppressive therapy can be reintroduced after all vesicles have crusted over and fever has resolved, not simply after starting antivirals. 1

Do not use oral antivirals for severe disease in immunocompromised patients, as this represents inadequate treatment. 4 Severely immunocompromised patients with systemic HSV or disseminated VZV require intravenous acyclovir from the outset to prevent devastating complications. 1, 4

Do not continue immunosuppression during life-threatening viral infections, as reduction or cessation of immunosuppressive medication is associated with clinical improvement and decreased mortality. 1

Post-Recovery Considerations

After recovery from herpes virus infection, consider prophylactic antiviral therapy (acyclovir 400 mg twice daily or valacyclovir 500 mg daily) for patients with recurrent HSV while on iguratimod. 1 For VZV prevention, strongly recommend recombinant zoster vaccine (Shingrix) for all patients ≥50 years before or after recovery from acute infection. 1, 2, 3