BACKGROUND: Patient-reported allergies (PRAs) have been identified as a risk factor for worse outcomes and less satisfaction in patients undergoing knee and hip arthroplasty. Similar associations have not been elucidated in shoulder arthroplasty patients; however, previous research is sparse. The purpose of this study was to assess the outcomes following shoulder arthroplasty surgery with respect to patient-reported drug allergies. It was hypothesized that a higher number of allergies would be associated with worse patient-reported outcomes (PROs) following shoulder arthroplasty surgery. METHODS: Consecutive patients aged 18-89 years at the time of surgery who underwent primary shoulder arthroplasty between October 2005 and March 2018 performed by a single surgeon and had a minimum follow-up period of 1 year were reviewed. PRO scores, including the American Shoulder and Elbow Surgeons score, Single Assessment Numerical Evaluation score, QuickDASH (short version of Disabilities of the Arm, Shoulder and Hand questionnaire) score, and 12-Item Short Form Health Survey Physical Component Summary and Mental Component Summary scores, as well as patient satisfaction, were collected preoperatively and postoperatively. Early clinical failures were reported. Subjects were categorized into a 3-level factor based on the number of PRAs (0, 1, or ≥2), and bivariate comparisons of mean postoperative PRO scores were performed using Kruskal-Wallis analyses. Additionally, multivariate regression was performed to assess the effect of PRAs on PROs while controlling for age, sex, arthroplasty type, baseline PRO scores, and Charlson Comorbidity Index. RESULTS: Overall, 411 shoulders were included in the final study population (367 patients, 44 of whom were treated bilaterally). The population was predominately male patients (n = 265, 64.5%), and the median age at the time of surgery was 66.5 years (first quartile-third quartile, 61.3-71.4 years). Of the patients, 253 (61.6%) underwent total shoulder arthroplasty (TSA) whereas 158 (38.4%) underwent reverse TSA. Five patients (2 TSA and 3 reverse TSA patients) experienced early clinical failure and required revision surgery. Minimum 1-year PROs were obtained for 345 of 406 patients (85.0%) with a mean follow-up period of 1.9 ± 1.2 years. Nearly all postoperative PROs reflected a trend of worse outcomes with more preoperative PRAs; however, the QuickDASH score was the only score showing a significant difference between allergy groups (P = .004). Pair-wise comparison using Nemenyi post hoc testing showed that the QuickDASH score was significantly higher (worse outcomes) for the group with ≥2 allergies compared with the group with 0 allergies. PRA was found to be a statistically significant predictor of higher postoperative QuickDASH scores (P = .043) and was more influential than the Charlson Comorbidity Index and sex. Additionally, PRA was the only statistically significant predictor of patient satisfaction (P = .016). CONCLUSION: An increasing number of preoperative PRAs is associated with worse PROs and patient satisfaction following shoulder arthroplasty. The number of PRAs was the most influential predictor of patient satisfaction.