More than half of patients with pemphigus experience relapse during the disease course. The risk factors and clinical and immunological characteristics of relapse remain largely unclear. To elucidate the risk factors and clinical features of pemphigus relapse. We carried out a retrospective review of the clinical records of 42 cases of pemphigus at a single centre. Sixty-two per cent of patients experienced relapse, usually when oral prednisolone was tapered to around 0·1 mg kg-1 . In mucocutaneous pemphigus vulgaris (mcPV), the initial doses (mean ± SD) of prednisolone were significantly lower in patients with relapse (0·78 ± 0·24 mg kg-1 ) than in those without relapse (1·01 ± 0·01 mg kg-1 ). At relapse, mcPV shifted to mucosal dominant PV (mPV; 40%), pemphigus foliaceus (PF) (20%) or 'other' (20%). In contrast, relapsing mPV and PF had the same clinical phenotypes as the initial phenotypes. Patients with both anti-desmoglein (Dsg)1 and anti-Dsg3 antibodies at onset had recurrence with anti-Dsg3 antibodies alone (40%), with both anti-Dsg1 and anti-Dsg3 antibodies (30%), with anti-Dsg1 antibody alone (20%) or were subthreshold (10%). mcPV shows transitions in clinical phenotype and autoantibody profile at relapse. At least 1 mg kg-1 daily of prednisolone, especially for patients with mcPV, and prudent tapering around 0·1 mg kg-1 may lead to better outcomes. © 2018 British Association of Dermatologists.