AbstractBackgroundHidradenitis suppurativa (HS) is a multifactorial inflammatory skin disease that is considered to be an immune‐mediated inflammatory disease (IMID). Up till now, the impact of lifestyle on (the development of) HS has not been thoroughly investigated.ObjectivesTo investigate the effect of dietary intake and physical activity (PA) on (the development of) HS.Materials and MethodsA nested case–control study was performed within the longitudinal Lifelines Cohort Study, that took place in the Northern Netherlands, and identified 1004 adult eligible HS patients and 5000 age‐matched controls. Dietary data were collected using a validated food frequency questionnaire, subsequently translated to the Lifelines Diet Score (LLDS), alternate Mediterranean Diet Score (aMED) and Dutch Dietary Guidelines score (DDG), with higher scores reflecting healthier dietary habits. PA was measured by the Short Questionnaire to Assess Health‐enhancing PA score. Logistic regression analyses were performed between dietary/PA scores, and the prevalence/development and severity of HS.ResultsCompared to controls, HS patients scored lower on the LLDS [OR = 0.98; 95% CI 0.96–0.99], aMED [0.93; 0.89–0.97] and DDG [0.93; 0.88–0.97] with multivariable regression analysis. Overall, this indicates less adherence to dietary recommendations and consumption of a low‐quality diet in the HS population. Lower adherence to the LLDS and DDG was also significantly associated with a higher likelihood to HS development in univariable regression analysis [0.96; 0.94–0.99 and 0.91; 0.84–0.99, respectively], and a trend of decreased adherence to the aMED [0.93; 0.85–1.02] was noted. Besides, PA levels were found significantly lower in HS patients (p ≤ 0.001).Conclusions and RelevancePoor diet quality and lower quantities of PA were associated with HS in the general population. Identifying dietary and PA habits of HS patients can contribute to the development of prevention strategies for HS specifically, and for IMIDs in general.