Randomized double‐blind cross‐over trial of bath additive containing tannic acid in patients with atopic dermatitis

Abstract Skin care against aggravating factors is important to prevent skin lesions from flare‐up in the treatment of atopic dermatitis (AD). Tannic acid (TA), a natural polyphenolic and protein‐denaturing agent, has activity to denature antigens relevant to the AD flare. To assess the efficacy of a bath additive containing TA (TA‐bath additive) on pruritus of AD, we carried out a randomized double‐blind trial, in which 21 patients with AD completed the blinded sequential treatments with the TA‐bath additive and a bath additive without TA (placebo‐bath additive) in a cross‐over manner. A significant improvement of pruritus was observed in the afternoon and night by using the TA‐bath additive and in the afternoon by the placebo‐bath additive in patients with AD. No superiority of the TA‐bath additive to the placebo was revealed in the overall patient cohort. However, the added TA in the bath additive exerted its efficacy especially on itch at night in patients with mild‐to‐moderate disease. Bathing by using the series of the bath additive with TA and that without TA improved AD skin lesions throughout this study. No adverse effects related to the use of the TA‐ and placebo‐bath additives were observed. In conclusion, the bath additive containing TA may help skin care of patients with itch and skin lesions of the mild AD.