LAUSR

PURPOSE We report a probable case of morbilliform drug eruption secondary to fidaxomicin in a patient with Clostridioides difficile infection (CDI). SUMMARY A 62-year-old female presented to our institution's emergency department (ED) with symptoms consistent with Clostridioides difficile infection. The patient was prescribed 2 weeks of oral vancomycin for CDI prior to presentation. Given insufficient response to vancomycin, the patient was started on fidaxomicin with a planned 10-day course. After 2 doses of fidaxomicin, the patient developed a rash on her back that spread within 24 hours. The patient did not experience relief upon administration of a variety of medications for allergic reaction. Improvement was noted upon discontinuation of fidaxomicin. The Food and Drug Administration reports that < 2% of adults treated with fidaxomicin experience a rash as an adverse effect. CONCLUSION Fidaxomicin was a probable cause of morbilliform drug eruption in our patient with CDI. The patient improved upon discontinuation of fidaxomicin.