Updated: April 9, 2026

YF-Vax Drug Interactions: What to Avoid and What to Tell Your Doctor

Author

Peter Daggett

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Immunosuppressants: Contraindicated with YF-Vax
Corticosteroids: Dose-Dependent Concern
Other Live Vaccines: Spacing Matters
Chloroquine and Hydroxychloroquine: Minor Interaction
Immune Globulin and Blood Products
Full List of Medications to Disclose Before YF-Vax

YF-Vax is a live vaccine with important drug interactions — especially with immunosuppressants, corticosteroids, and other live vaccines. Here's what to tell your doctor before vaccination.

Because YF-Vax contains a live, replicating virus, it has a distinct and important interaction profile compared to inactivated vaccines. The key concern isn't a simple pill-on-pill reaction — it's about whether your medications or medical conditions could interfere with the vaccine's ability to generate immunity, or increase the risk of serious adverse events.

Before receiving YF-Vax, tell your healthcare provider about every medication, supplement, and recent vaccine you've received. Here's what matters most.

Immunosuppressants: Contraindicated with YF-Vax

Patients on immunosuppressive therapy should

not receive YF-Vax in most cases. Immunosuppressive agents decrease the immune system's ability to control the live attenuated virus, potentially allowing it to replicate uncontrollably and cause serious disease. The following categories of drugs represent contraindications or strong avoidance recommendations:

Biologics (immune checkpoint inhibitors, monoclonal antibodies): Belimumab, certolizumab pegol, ibrutinib — all contraindicated. Do not administer live vaccines within 30 days before or concurrently with these agents.

CAR-T cell therapies: Agents like ciltacabtagene autoleucel — avoid live vaccines at least 6 weeks before starting lymphodepleting chemotherapy, during treatment, and until immune recovery following treatment.

Conventional immunosuppressants: Cyclosporine, azathioprine, mycophenolate, and similar agents — avoid live vaccines. If immunosuppressive therapy has recently ended, wait at least 3 months after stopping before receiving YF-Vax.

Corticosteroids: Dose-Dependent Concern

Systemic corticosteroids (oral prednisone, hydrocortisone, prednisolone, methylprednisolone, deflazacort) can reduce immune response to YF-Vax and increase the risk of adverse events. The concern is dose- and duration-dependent:

Short-course, low-dose steroids: Generally considered lower risk, but discuss with your provider.

High-dose or long-term steroids: Immunosuppressive doses are a contraindication. The vaccine should be deferred until steroid use is discontinued and adequate immune function has recovered.

Local/intra-articular steroid injections: These are not considered to pose a significant hazard to YF-Vax recipients.

Other Live Vaccines: Spacing Matters

If you are getting multiple vaccines at once, the type of each vaccine matters:

Live vaccines given simultaneously: ACIP recommends that live viral vaccines be given at the same time if not being co-administered at different sites. This is acceptable and does not reduce the immune response to either vaccine.

Live vaccines given sequentially: If live vaccines are not given simultaneously, space them at least 4 weeks apart. This includes MMR, varicella, and other live vaccines. Giving live vaccines too close together can impair the immune response to one or both vaccines.

Inactivated vaccines: Can be administered at any time before or after YF-Vax — simultaneously or at any interval. This includes hepatitis A, hepatitis B, meningococcal, typhoid Vi (injectable), and flu shot (inactivated).

Chloroquine and Hydroxychloroquine: Minor Interaction

Anti-malarial medications like chloroquine and hydroxychloroquine may inhibit replication of the yellow fever vaccine virus in laboratory studies. However, clinical data show that antibody responses to YF-Vax are not adversely affected in people taking these medications. The prescribing information notes this interaction as minor and unlikely to be clinically significant.

Immune Globulin and Blood Products

Limited data exist on the effect of immune globulin on the response to YF-Vax. Unlike MMR vaccine (where immune globulin should be spaced apart), YF-Vax appears to have lower susceptibility to immune globulin interference based on available evidence. Discuss your specific situation with your travel medicine provider if you have recently received immune globulin products.

Full List of Medications to Disclose Before YF-Vax

Before receiving YF-Vax, tell your provider about:

Any biological medications (TNF inhibitors, monoclonal antibodies, checkpoint inhibitors)

Oral or IV corticosteroids

Chemotherapy or immunosuppressive drugs for transplant

Any other live vaccines received or scheduled within 4 weeks

Anti-malarial medications (chloroquine, hydroxychloroquine, mefloquine)

HIV medications and current CD4 count if HIV-positive

Any history of egg, chicken, or gelatin allergy (vaccine components)

Frequently Asked Questions

Methotrexate and similar DMARDs (disease-modifying antirheumatic drugs) are immunosuppressive. Whether YF-Vax is safe depends on the dose, duration, and reason for the medication. Low-dose methotrexate (as used for rheumatoid arthritis) may be a precaution rather than an absolute contraindication in some cases, but this requires individual risk-benefit assessment by your rheumatologist and travel medicine provider. Do not get YF-Vax without discussing your DMARD therapy first.

In general, live vaccines should be deferred until at least 3 months after stopping immunosuppressive therapy, once adequate immune function has recovered. For biologics like certolizumab or belimumab, live vaccines should not be given within 30 days before or concurrently. These are general guidelines — your specific case should be evaluated by your prescribing provider.

Yes. While chloroquine and hydroxychloroquine may inhibit replication of the yellow fever vaccine virus in laboratory conditions, clinical studies show this does not meaningfully reduce antibody responses in vaccinated people. The interaction is considered minor, and both can be administered together for travel health preparedness.

Yes. Inactivated vaccines — including inactivated influenza vaccines — can be administered at any time before or after YF-Vax, whether simultaneously or at any interval. The only concern about vaccine spacing applies to other live vaccines (e.g., MMR, varicella), which should be given simultaneously or at least 4 weeks apart.

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