Background: Irritable bowel syndrome (IBS) affects 10-15% of adults in the US, and is associated with significant impairment in health-related quality of life (HRQoL); however, information specific to the diarrhea subtype (IBS-D) is lacking. We assessed the impact of IBS-D on HRQoL, work productivity, and daily activities, and the associated indirect costs, among a sample of the US population. Methods: Respondents (>= 18 years) from the 2012 US National Health and Wellness Survey who reported an IBS-D diagnosis by a physician or symptoms consistent with Rome II criteria for IBS-D were identified as having IBS-D. Controls included respondents without IBS-D or inflammatory bowel disease. HRQoL was assessed via the Short Form 36 Health Survey version 2 questionnaire and summarized into Mental and Physical Component Summary (MCS; PCS) scores and a Short Form-6 dimension (SF-6D) utility score. Work and activity impairment were assessed via the Work Productivity and Activity Impairment Questionnaire: General Health version (WPAI: GH), which measures absenteeism, presenteeism, overall work productivity loss, and daily activity impairment. Indirect costs were calculated using unit cost data from the Bureau of Labor Statistics and variables from the WPAI: GH. Generalized linear models were used to examine differences in health outcomes between respondents with IBS-D and controls, controlling for demographic and health characteristics. Results: In total, 66,491 respondents (1102 IBS-D; 65,389 controls) were analyzed. Mean age was 48.7 years; 50% were female. Compared with controls, the IBS-D cohort reported significantly lower HRQoL (mean MCS: 45.16 vs. 49. 48; p < 0.001; mean PCS: 47.29 vs. 50.67; p < 0.001; mean SF-6D: 0.677 vs. 0.741; p < 0.001) and greater absenteeism (5.1% vs. 2.9%; p = 0.004), presenteeism (17.9% vs. 11.3%; p < 0.001), overall work productivity loss (20.7% vs. 13.2%; p < 0.001), and activity impairment (29.6% vs. 18.9%; p < 0.001). Respondents with IBS-D also incurred an estimated $ 2486 more in indirect costs ($ 7008 vs. $ 4522; p < 0.001). Conclusions: Compared with controls, IBS-D is associated with significantly lower HRQoL, greater impairments in work and daily activities, and higher indirect costs, imposing a substantial burden on patients and employers. These findings suggest a significant unmet need exists for effective IBS-D treatments.