Coming clean on bleach baths for atopic dermatitis
By Warren R. Heymann, MD
Oct. 23, 2019
Vol. 1, No. 33
Bleach baths have become popularized over the past decade in managing atopic dermatitis (AD). I have been a strong proponent, often telling patients (and their parents) that the procedure would help decolonize the skin and prevent Staphylococcal infection, a well-known aggravator of AD. Recent data suggest that I may have been misinformed (or overly optimistic) — it is time to come clean.
Sodium hypochlorite (bleach, Dakin, or Carrel-Dakin solution) is produced by the mixture of sodium peroxide (NaO) and hydrochloric acid (HCl). The main active agent in bleach is created when chlorine in the solution reacts with water in the environment to form hypochlorous acid (HCLO), reportedly responsible for the antibacterial effect. The solution was originally formulated as a battlefield wound antiseptic during World War I by the English chemist Henry Dakin and the French surgeon Alexis Carrel. (1)
It is hard to pinpoint where the trend to use bleach baths for AD began. Krakowski et al reference a poster by Metry et al presented at the 2007 meeting of the Society of Pediatric Dermatology. Krakowski et al state: “Diluted bleach baths, analogous to swimming in a chlorinated pool, are an adjuvant antiinfective treatment that can help decrease the number of local skin infections and reduce the need for systemic antibiotics for patients with AD with heavily colonized and/or superinfected skin.” (2)
If bleach baths are beneficial in AD, it may not be due to direct antibacterial effects. Sawada et al note that the standard recommendation is to use one-quarter to one-half cup of 6% household bleach in a bathtub full of water (40 gallons). To obtain an antibacterial effect, bleach concentrations must be at least 0.03%, which is greater than is safe for the skin or that has been proposed for clinical use. Their microbiologic study of bacterial colony growth clearly demonstrated that bleach baths had no direct bacteriocidal activity against S aureus or S epidermidis. The authors concluded that potential benefit from bleach baths cannot be attributed to direct killing or inhibition of S aureus. (3) In several experiments utilizing cell cultures and mice, Leung et al demonstrated that bleach inhibited the activity of the inhibitor of NF-κB kinase (IKK), a key regulator of NF-κB activation, by oxidizing cysteine residues. (4)
Regardless of the mechanism, are bleach baths effective in AD? Conflicting literature abounds.
Chopra et al performed a systematic review to study the efficacy of bleach baths in reducing the severity of AD. Four studies reported significantly decreased AD severity in patients treated with bleach on at least 1 time point. However, of 4 studies comparing bleach with water baths, only 2 found significantly greater decreases in AD severity with bleach baths, 1 found greater decreases with water baths, and 1 found no significant differences. In pooled analyses, there were no significant differences observed between bleach versus water baths at 4 weeks versus baseline for the Eczema Area and Severity Index or body surface area. The authors concluded: “while bleach baths are effective in reducing AD severity, they do not appear to be more effective than water bath alone. However, there are a number of limitations with the currently available studies. Future, larger-scale RCT [randomized controlled trials] are needed that address these limitations.” (5)
Asch et al retrospectively assessed 753 AD patients of whom 351 (46.6%) had culture-proven or clinically suspected superinfection. The number of systemic antibiotic courses did not differ between those who received bathing recommendations and those who did not, nor between different anti-infective groups. The authors concluded that neither dilute acetic acid nor bleach baths were associated with fewer subsequent exposures to systemic antibiotics in the treatment of pediatric AD. (6)
Bleach may also be utilized as a body wash for those who prefer to shower, or if a tub is unavailable. Majewski et al performed a 6-week, prospective, open-label study in 50 patients (ages 6 months to 17 years) with moderate-to-severe AD and S aureus skin colonization documented by culture. Participants were instructed to continue using their current medications while using the study product, 0.006% sodium hypochlorite body wash, once daily to affected areas for 6 weeks. Several outcome measures were utilized including Investigator's Global Assessment, Eczema Area and Severity Index, and Family Dermatology Life Quality Index among others. Daily use of the 0.006% NaOCl body wash led to improvement for all outcome measures comparing baseline to 2-week and to 6-week evaluations. Of the 50 skin S aureus-positive subjects, 32/50 (64%) were still positive at 2 weeks. A 36.5% decrease in subject’s daily record of topical corticosteroid application at end of study compared to baseline was found. Participant surveys indicated preferences for the body wash over bleach baths. The authors concluded that sodium hypochlorite body wash improved all outcome measures for moderate-to-severe S aureus-colonized AD patients, suggesting that bleach has ameliorative effects other than antimicrobial actions. (7)
The theory that bleach baths improve AD by anti-infective means may be all wet, but perhaps other anti-inflammatory mechanisms may help ameliorate the disease. In my experience, most patients have accepted the recommendation willingly, with the occasional patient objecting to a burning sensation from the baths. Until prospective studies unequivocally state that there is no benefit to adding bleach (or certainly if there is any harm!), I will still recommend it for patients with the hope that it is adding at least a smidgen of value.
Point to remember: The jury on bleach baths is still out. While anti-bacterial attributes may be lacking, bleach may be helpful by other mechanisms. Future randomized controlled trials will be key in determining its proper place in the management of AD.
Our expert’s viewpoint
Andrew C. Krakowski
Network Chair of Dermatology
Program Director for the Residency in Dermatology
St. Luke’s University Health Network
I was a research fellow when the atopic dermatitis lecture circuit had just started to pick up and run with the notion that bleach baths could serve as adjuvant therapy for the control of Staph on atopic skin. I trained at UCSD, and our chair, Richard Gallo — who is well-known for his work on innate immunity — often challenged us to consider how a strong “base” such as bleach would, ultimately, affect the skin’s acid mantle. He suggested that vinegar soaks might be more physiologic. It is amazing to me that this hypothesis has not been tested in a large, well-controlled study of atopic dermatitis patients.
As far as prospectively demonstrating the utility of bleach baths, “exposure to systemic antibiotics” is an inherently flawed clinical endpoint. Instead, I would encourage future investigators to consider “number of days with an active flare” and “number of days between flares” as more telling measures of an adjuvant intervention’s success. We must also differentiate between “infection” and “colonization,” as a positive skin culture only reveals the presence of bacteria — not a clinical diagnosis of true infection. Likewise, we should attempt to better verify the final concentration of solution in which our atopic patients are soaking and standardize the time for which they remain immersed in the tub. After-care must also be considered as patients should rinse off residual chlorine with fresh water or risk drying out their skin even further. Perhaps most critically, as Chang and Eichenfield have shown (Pediatr Dermatol. 2009 May-Jun;26(3):273-8.), patients need to moisturize soon after a bath.
At the end of the day, I utilize bleach baths as a means of giving my pediatric patients — or more accurately their parents — an inexpensive, accessible, at-home tool they can use to feel empowered about their own skin condition. The idea of “making a pool in your bathtub” is easily relatable, and working to reduce the number of days in which a flare is active and increasing the number of days between flares sets realistic goals that can be easily assessed by both clinician and layperson alike. Until I see evidence that suggests bleach baths are actually unsafe, I will continue to use them in my armamentarium for treating moderate to severe atopic dermatitis patients.
Keyes M, Thibodeau R. Dakin solution (Sodium Hypochlorite). StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019-2019 Apr 5.
Krakowski AC, Eichenfield LF, Dohil MA. Management of atopic dermatitis in the pediatric population. Pediatrics 2008;122: 812-824.
Sawada Y, Tong Y, Barangi M, Hata T, et al. Dilute bleach baths used for treatment of atopic dermatitis are not antimicrobial in vitro. J Allergy Clin Immunol 2019; 143: 1946-1948.
Leung TH, Zhang LF, Wang J, Ning S, et al. Topical hypochlorite ameliorates NF-kappa B-mediated skin disease in mice. J Clin Invest 2013; 123: 5361-5370.
Chopra R, Vakharia PP, Sacotte R, Silverberg JI. Efficacy of bleach baths in reducing severity of atopic dermatitis: A systematic review and meta-analysis. Ann Allergy Asthma Immunol 2017; 119: 435-440.
Asch S, Vork DL, Joseph J, Major-Elechi B, Tollefson MM. Comparison of bleach, acetic acid, and other topical anti-infective treatments in pediatric atopic dermatitis: A retrospective cohort study on antibiotic exposure. Pediatr Dermatol 2019; 36: 115-120.
Majewski S, Bhattacharya T. Asztalos M, Bohaty B, et al. Sodium hypochlorite body wash in the management of Staphylococcus aureus-colonized moderate-to-severe atopic dermatitis in infants, children, and adolescents. Pediatr Dermatol 2019; 36: 442-447.
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