BackgroundChildhood eczema is very common. Treatment often includes emollient bath additives, despite there being little evidence of their effectiveness.ObjectivesTo determine the clinical effectiveness and cost-effectiveness of emollient bath additives in the management of childhood eczema.DesignPragmatic, randomised, open-label, multicentre superiority trial with two parallel groups.SettingNinety-six general practices in Wales, the west of England and southern England. Invitation by personal letter or opportunistically.ParticipantsChildren aged between 12 months and 12 years fulfilling the UK Diagnostic Criteria for Atopic Eczema. Children with inactive or very mild eczema (a score of ≤ 5 on the Nottingham Eczema Severity Scale) were excluded, as were children who bathed less than once per week or whose parents/carers were not prepared to accept randomisation.InterventionsThe intervention group were prescribed bath additives by their usual clinical team and were asked to use them regularly for 12 months. The control group were asked to use no bath additives for 12 months. Both groups continued standard eczema management, including regular leave-on emollients and topical corticosteroids (TCSs) when required.Main outcome measuresThe primary outcome was eczema control measured by Patient Oriented Eczema Measure [POEM, 0 (clear) to 28 (severe)] weekly for 16 weeks. The secondary outcomes were eczema severity over 1 year (4-weekly POEM), number of eczema exacerbations, disease-specific quality of life (QoL) (Dermatitis Family Impact Questionnaire), generic QoL (Child Health Utility-9 Dimensions) and type and quantity of topical steroid/calcineurin inhibitors prescribed. Children were randomised (1 : 1) using online software to either bath additives plus standard eczema care or standard eczema care alone, stratified by recruiting centre, and there was open-label blinding.ResultsFrom December 2014 to May 2016, 482 children were randomised: 51% were female, 84% were white and the mean age was 5 years (n = 264 in the intervention group,n = 218 in the control group). Reported adherence to randomised treatment allocation was > 92% in both groups, with 76.7% of participants completing at least 12 (80%) of the first 16 weekly questionnaires for the primary outcome. Baseline POEM score was 9.5 [standard deviation (SD) 5.7] in the bath additives group and 10.1 (SD 5.8) in the no bath additives group. Average POEM score over the first 16 weeks was 7.5 (SD 6.0) in the bath additives group and 8.4 (SD 6.0) in the no bath additives group, with no statistically significant difference between the groups. After controlling for baseline severity and confounders (ethnicity, TCS use, soap substitute use) and allowing for clustering of participants within centres and responses within participants over time, POEM scores in the no bath additive group were 0.41 points higher than in the bath additive group (95% confidence interval –0.27 to 1.10), which is well below the published minimal clinically important difference of 3 points. There was no difference between groups in secondary outcomes or in adverse effects such as redness, stinging or slipping.LimitationsSimple randomisation resulted in an imbalance in baseline group size, although baseline characteristics were well balanced between groups.ConclusionThis trial found no evidence of clinical benefit of including emollient bath additives in the standard management of childhood eczema.Future workFurther research is required on optimal regimens of leave-on emollients and the use of emollients as soap substitutes.Trial registrationCurrent Controlled Trials ISRCTN84102309.FundingThis project was funded by the NIHR Health Technology Assessment Programme and will be published in full inHealth Technology Assessment; Vol. 22, No. 57. See the NIHR Journals Library website for further project information.