Detergent enzymes may cause skin irritation, leading some physicians to advise patients with atopic eczema to avoid the use of such detergents in favour of alternative "non-biological" detergents.31 We located one RCT testing the hypothesis that enzyme-containing detergents are more likely to aggravate atopic eczema than a non-biological detergent,32 and one that looked at the impact of using fabric softeners in adults with atopic dermatitis.33
In the first study,32 26 adults with mild-to-moderate atopic eczema (mean age 25 years) were randomised in a double-blind crossover study to use either a trial detergent containing enzymes or a visually identical detergent without enzymes for one month. There was a 1-month wash-out period before randomisation, when participants used their usual washing powder. Topical steroids were permitted during the study and were weighed. In the 25 patients who completed the trial there was no difference between the two groups in terms of disease severity (SCORAD scores of 29 in each group, 95% CI for mean difference -4 to +5). Similar results were found for the use of topical steroids, patient-reported itch and eczema activity.
The study looking at fabric softeners33 was a single-blind randomised trial using a left-right comparison design for a period of 12 days. Twenty volunteers with a history of atopic dermatitis were enrolled in the study (none had active lesions at the time of enrolment). In order to simulate realistic conditions of skin damage, sodium lauryl sulphate was applied to each volar forearm under occlusion 3 days before the start of the study. A control patch using water was also applied to each arm. Repetitive wash tests were performed three times a day using softened or unsoftened fabric in random order to each arm. The investigator was blinded to the fabric used at each site. Both for the control and pre-irritated skin, all measured parameters indicated that "softened" fabric was less aggressive to the skin than "unsoftened" fabric.
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