Immediate hypersensitivity reaction followed by successful oral desensitization to ursodiol

BACKGROUND: Immediate hypersensitivity reaction to ursodiol is rare and there is no previously published protocol on ursodiol desensitization. CASE PRESENTATION: A 59-year-old woman with primary biliary cholangitis (PBC) developed an immediate hypersensitivity reaction to ursodiol—the first-line treatment for PBC. When she switched to a second-line treatment, her PBC continued to progress. As such, she completed a novel 12-step desensitization protocol to oral ursodiol. She experienced recurrent pruritus after each dose following desensitization, which subsided after a month of being on daily ursodiol. CONCLUSION: Immediate hypersensitivity reaction to ursodiol is uncommon. Our case demonstrated that this novel desensitization protocol to ursodiol could be safely implemented when alternative options are not available or have proven inferior in efficacy.