Incident Rosacea and Related Dermatoses in Estrogen-Exposed Females: A Large-Scale Age-Stratified Cohort Study

Background: Rosacea is a chronic inflammatory facial dermatosis that disproportionately affects women and may vary across hormonal life stages. Fluctuations in estrogen levels across the female lifespan, particularly during perimenopause and postmenopausal stages, have been hypothesized to contribute to the development of inflammatory, pigmentary, and androgen-mediated dermatologic conditions. However, population-level data evaluating the association between estrogen exposure and incident rosacea across hormonally defined life stages remain limited. This study assesses the association between exogenous estrogen exposure and incident rosacea and related dermatological conditions across premenopausal, perimenopausal, and postmenopausal women. Methods: A retrospective cohort study was conducted using the TriNetX Research Network. Female patients were stratified into premenopausal (< 44 years), perimenopausal (45–55 years), and postmenopausal (≥ 56 years) cohorts. Within each age stratum, estrogen-exposed patients, defined by documented estrogen-containing hormonal contraceptive use or hormone replacement therapy use, were propensity score-matched 1:1 to estrogen-unexposed controls. The primary outcome was incident rosacea (ICD-10 L71.x) within three years following the index event. Secondary outcomes included other/unspecified rosacea, perioral dermatitis, and rhinophyma. Time-to-event analyses were performed using Kaplan–Meier methods and Cox proportional hazards models. Results: After matching, cohorts included 742,051 premenopausal, 54,248 perimenopausal, and 378,572 postmenopausal women per exposure group. Across all age groups, estrogen exposure was associated with a significantly lower recorded incidence of rosacea. Hazard ratios (HR) were 0.75 (95% CI 0.72–0.78; log-rank p < 0.001) in premenopausal women, 0.77 (95% CI 0.69–0.85; p < 0.001) in perimenopausal women, and 0.67 (95% CI 0.65–0.70; p < 0.001) in postmenopausal women. Similar associations were observed for other rosacea subtypes, perioral dermatitis, and rhinophyma across cohorts. Conclusion: Exogenous estrogen exposure was consistently associated with a lower recorded incidence of rosacea and related inflammatory facial dermatoses across female hormonal life stages. These findings underscore the importance of hormonal context and diagnostic patterns in rosacea epidemiology and support further investigation into hormonal modulation of inflammatory skin disease.