# Safety Evaluation of Fine Bubble Shower Washing for Patients With Atopic Dermatitis: A Double‐Blind, Randomized, Prospective Crossover Clinical Trial

## TL;DR

A study found that using a fine bubble shower is safe for people with mild atopic dermatitis and does not worsen their skin condition.

## Contribution

This is the first double-blind, randomized trial evaluating the safety of fine bubble showers for atopic dermatitis.

## Key findings

- Fine bubble showers did not worsen eczema severity or skin barrier function in adults with mild atopic dermatitis.
- No serious adverse events occurred during the 4-week study period.
- Fine bubble showers were not shown to be superior to conventional showers in improving skin condition.

## Abstract

Atopic dermatitis (AD) involves chronic eczema resulting from barrier dysfunction. Fine bubble (FB) technology generates microbubbles (< 100 μm) and ultrafine bubbles (< 1 μm) for surfactant‐sparing cleansing. We assessed the short‐term safety of an FB shower in AD. In this double‐blind, randomized, crossover study, adults with mild AD completed two 2‐week periods separated by a 2‐week washout in sequence. Bathing instructions and petrolatum moisturizer use were standardized and enforced. The Eczema Area and Severity Index (EASI) was scored using whole‐body photographs by a blinded team. Transepidermal water loss (TEWL) and stratum corneum hydration were measured on Days 0, 14, and 28. Because baselines were unavailable for the second 2‐week period, the primary analysis compared Day 0–14 changes between groups using baseline‐adjusted analysis of covariance; Day 0–28 changes were also explored. The primary outcomes were EASI changes; TEWL and hydration were the secondary outcomes. Groups used a conventional shower (control) first and then FB shower second or vice versa (once each). Twenty‐three participants were analyzed (mean age 40.9 ± 8 years; 83% male). Day 0–14 EASI changes did not differ between FB and control (0.62 ± 2.21 vs. 0.05 ± 0.68; F = 0.93, p = 0.35). EASI changes to Day 28 were nonsignificant (0.02 ± 1.65 vs. −0.03 ± 1.02; p = 0.90). TEWL changes for Days 0–14 (0.31 ± 4.75 vs. 1.09 ± 6.21 g/m2/h) and to Day 28 (5.49 ± 14.43 vs. −0.27 ± 5.28 g/m2/h) showed no between‐group differences. Hydration changes were similar for Days 0–14 (5.53 ± 13.23 vs. 6.14 ± 7.96 AU) and to Day 28 (18.41 ± 10.33 vs. 21.09 ± 11.07 AU). No serious adverse events or discontinuations for worsening symptoms occurred. Under standardized, low‐irritant conditions, the FB shower was well‐tolerated by adults with mild AD and did not worsen severity or barrier indices over 4 weeks. However, the superiority of FB to a conventional shower was not demonstrated.