Yes, you can safely receive a flu shot while taking Xifaxan (rifaximin)
There are no contraindications or drug interactions between rifaximin (Xifaxan) and influenza vaccines, and you should proceed with vaccination as recommended.
Key Points
No Known Interactions
The FDA drug label for Xifaxan does not list any contraindications or warnings regarding influenza vaccination 1. Rifaximin is a minimally absorbed, gut-targeted antibiotic that achieves high intestinal concentrations with minimal systemic exposure, which further reduces the likelihood of any interaction with vaccines 2, 3.
Supporting Evidence
Rifamycin class data: Historical research on rifampin (a related rifamycin antibiotic) demonstrated that long-term therapy did not suppress the secondary antibody response to influenza vaccination 4. While rifampin has much greater systemic absorption than rifaximin, this provides reassuring evidence that the rifamycin class does not interfere with vaccine immunogenicity.
Current vaccination guidelines: The 2024-25 ACIP influenza vaccination guidelines specify that inactivated influenza vaccines (IIVs) and recombinant influenza vaccines (RIVs) can be administered with other medications without concern for drug interactions 5. The only medications that interfere with influenza vaccines are antiviral medications specific to influenza (oseltamivir, zanamivir, peramivir, baloxavir), and only when given with the live attenuated influenza vaccine (LAIV) 5.
Practical Considerations
- Timing: You do not need to adjust the timing of your Xifaxan doses around flu vaccination
- Vaccine type: All influenza vaccine formulations (standard-dose, high-dose, adjuvanted, recombinant) are appropriate while taking Xifaxan
- Continue your medication: Do not interrupt your Xifaxan therapy for vaccination
Important Caveat
If you are taking Xifaxan for hepatic encephalopathy and have severe liver disease (Child-Pugh C), discuss vaccination timing with your provider, not because of the Xifaxan itself, but because severe liver disease may affect vaccine response. However, influenza vaccination remains particularly important in patients with chronic liver disease due to their increased risk of complications from influenza.