Severe Multiple Drug Intolerance Syndrome in Fibromyalgia and Irritable Bowel Syndrome

Background: Multiple drug intolerance syndrome (MDIS) describes patients with multiple nonimmunologically mediated adverse reactions to medications. Patients with more than 10 medication intolerance labels are considered to have severe MDIS. There is overlap in the characteristics of patients with MDIS and fibromyalgia and irritable bowel syndrome (IBS). Severe MDIS can limit treatment options in this already complex patient group. Objective: This study assessed the prevalence of severe MDIS in patients with fibromyalgia and IBS and its associated risk factors. Methods: A retrospective chart review identified patients diagnosed with fibromyalgia or IBS who had been seen at a large academic center from August 2019 to July 2020. Exact birthdate- and sex-matched controls who had been seen within the same time frame were selected at random. Listed drug intolerance data and patient characteristics were then analyzed with logistic regression and χ² testing. Results: Patients with fibromyalgia and IBS were 12 and 3 times more likely to have severe MDIS compared with controls, respectively. Severe MDIS was associated with polypharmacy in both groups. Opiates were the most frequently reported drug intolerance across all participants. Although patients with IBS more often reported gastrointestinal symptoms as adverse reactions, individuals with fibromyalgia did not more frequently report pain or behavioral changes as adverse reactions. Conclusions: There was an increased rate of severe MDIS in patients diagnosed with fibromyalgia and IBS. Additional studies are needed to better understand the morbidity of MDIS and how it can best be managed in patients with fibromyalgia and IBS.