Super-potent topical corticosteroids (CS) are the mainstay of treatment for bullous pemphigoid. Since super-potent topical CS have systemic effects due to their transcutaneous absorption, we assessed whether super-potent CS were responsible for hydro-saline retention (HSR) in bullous pemphigoid patients.From 2015 to 2017, patients with newly-diagnosed bullous pemphigoid treated using clobetasol propionate cream at a starting daily dose of 20 to 40 g were subsequently included in a prospective study. HSR was assessed by longitudinally measuring extracellular water (ECW) volume using bioimpedance analysis (BodyStat QuadScan 4000®) from Day 0 to Day 30 after the initiation of topical CS. Other parameters related to HSR such as weight, blood pressure, natriuresis and proteinuria, were also recorded.Twenty-nine patients (14 men and 15 women) of mean age 81.8 ± 9.3 years were included and analysed. The mean ECW volume decreased from Day 0 to Day 7 (18.1 ± 4.2 vs 16.7 ± 2.7, p = 0.0094) and was maintained from Day 7 to Day 30 (16.8 ± 2.8 vs 17.0 ± 3.4 L; p = 0.8040). Patient weight loss at Day 30 (69.9 ± 13.6 vs 72.5 ± 14.2 kg, p = 0.0085) was closely correlated with the decrease in ECW volume (r = 0.6740, p < 0.0001). No significant changes in natriuresis, 24-hour proteinuria or blood pressure were observed from Day 0 to Day 30.We found no evidence of HSR in bullous pemphigoid patients treated with super-potent topical CS. Conversely, ECW volume decreased from Day 0 to Day 30, which was correlated with patient weight loss.