Background: Pharmacotherapy, such as oral naltrexone, has proven effective in treating alcohol use disorder, although medication adherence has presented challenges. Although a formulation of extended-release naltrexone for intramuscular injection has been developed to counter daily adherence issues, injection-site reactions can occur within days of depot injection.
Case: The authors report a case of an individual with alcohol use disorder who had a previously undescribed delayed injection-site reaction that occurred 11 days after injection. Subsequent challenge with the medication resulted in recurrence of the reaction.
Discussion: Although extended-release naltrexone is generally well tolerated, injection-site reactions can complicate treatment and can appear more than 10 days after medication administration.
Keywords: Alcohol use disorder; extended-release naltrexone; injection-site reaction.