Abstract Background Smoking is associated with hidradenitis suppurativa (HS), but the clinical significance of smoking history is poorly understood. Objectives To examine the impact of smoking history and change in smoking behaviour on disease severity and treatment outcomes in patients with HS. Methods Patients with hospital‐diagnosed HS from two independent prospective cohorts, the Copenhagen Hidradenitis Suppurativa Cohort (HIS‐COP) and the Danish Skin Cohort (DSC), were included. Data on Hurley stage, International Hidradenitis Suppurativa Severity Score System (IHS4), Dermatology Life Quality Index (DLQI), boil‐associated pain and disease‐related bother were extracted from HIS‐COP to assess the association between smoking status at baseline and treatment outcomes. The DSC was used to assess the effect of change in smoking status on self‐reported disease severity and DLQI. Results In HIS‐COP ( n = 787), current smoking (53.9%) was associated with being Hurley stage III relative to I (OR = 2.38, 95% CI: 1.02–5.56, p = 0.044), higher IHS4 (OR = 1.05, 95% CI: 1.01–1.10, p = 0.018), higher DLQI (OR = 1.06, 95% CI: 1.03–1.09, p 0.05. Among patients initiated on tetracycline‐class treatment, current smokers had a significantly smaller mean (SD) reduction in IHS4 (2.5 (3.2) vs. 4.7 (4.9), p < 0.001), DLQI (4.2 (6.2) vs. 6.0 (6.4), p < 0.05) and percentage reduction in overall disease‐related bother (2.9 (4.0) vs. 4.3 (4.0), p < 0.05), compared to non‐smokers at follow‐up. Smoking cessation and initiation both showed a trend towards increased self‐reported disease severity after 12 months follow‐up; however, data were limited. Conclusions Smoking is associated with greater disease severity, poorer quality of life and worse treatment outcomes among patients with HS.
Poulsen et al. (2026) studied this question.