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Allergy to a Hot Tub Water Treatment Chemical: An Unexpectedly Common Cause of Generalized Dermatitis in Men



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[February 2010 • Volume 3 • Number 2]
Potassium peroxymonosulfate
(PPMS) is a potassium triple salt
(2KHSO5 • KHSO4 • K2SO4) that is
commonly used as an oxidizing
compound in pool and hot tub shock
treatments. It is the active ingredient
in Oxone®(DuPont), a pool and spa
oxidizer. In its disulfate form, PPMS is
used in hair-bleaching preparations,
flour, and denture cleanser, and has
been reported as a cause of contact
dermatitis, urticaria, and asthma.1–5
DuPont lists “allergic reactions in
sensitive individuals” as a potential
health hazard of Oxone in its safety
information.6However, contact
dermatitis induced by PPMS used in
pools or hot tubs has only been
documented in two case reports, both
of which involved hot tubs.1,4
In August of 2008, the authors
began to question all of their
patients with widespread dermatitis
about the use of hot tubs, and all
patients who used hot tubs were
tested for allergy to PPMS. Over the
ensuing 12 months, the authors
diagnosed six patients with allergy
to PPMS used as shock treatment in
their hot tubs or pools, all of whom
were demographically similar
(Figure 1).
The objective of the study was to
determine the demographic
characteristics of patients diagnosed
with allergy to PPMS and determine
the likelihood that these characteristics
represent a significant
A retrospective
chart review of all
patients diagnosed
with allergic contact
dermatitis due to
PPMS used as a shock
treatment in hot tubs
was performed. Data
was extracted on the
patients’ age and sex,
the duration and
distribution of
dermatitis, the rapidity
of flares after
exposure, the course
after diagnosis and
avoidance, history of
exposure, and the
results of patch
The age and gender, duration and
distribution of dermatitis, rapidity of
flares after exposure, course after
diagnosis and avoidance, history of
exposure, and the results of patch
testing are shown in Table 1.
The most notable aspect of these
patients is that they are all men. If
men and women were equally likely
to be allergic to PPMS used in hot
tubs, we can assume the theoretical
probability is that 50 percent of the
affected patients should be men. In
this assumption, the theoretical
probability of exactly eight out of
eight patients randomly being men is
1 in 256. This is a highly statistically
significant finding (p=0.0039),
meaning it is appropriate to reject
Section Editor: Matthew J. Zirwas, MD
Allergy to a Hot Tub Water
Treatment Chemical
An Unexpectedly Common Cause
of Generalized Dermatitis in Men
Patricia Gilligan, BS; Anthony Vander Horst, MA;
Matthew J. Zirwas, MD
Clinical Contact Dermatitis is a Special Section dedicated to featuring all types of contact dermatitis
and providing information on prevention, diagnosis, and treatment of these skin disorders. If you would
like to contribute to this section, please contact Matthew Zirwas, MD, at
[February 2010 • Volume 3 • Number 2] 55
the theory or hypothesis that men
and women are equally likely to be
affected by PPMS.
There are several other notable
aspects about these patients. First,
the age range is relatively small, with
patients all being between the ages of
45 and 80. Second, the distribution of
dermatitis follows what would be
expected. Third, in patients for whom
data was available, flares started
quickly following exposure, with an
increase in itching starting within 6 to
12 hours of exposure. Fourth, hot
tubs appear more likely to be
problematic than pools. Finally, it
appears that testing with ammonium
persulfate is an adequate screening
test for allergy to PPMS used as a
shock chemical, as 7 of 8 patients
tested positive with at least a 2+
Allergy to PPMS used as a hot tub
shock chemical appears to be much
more common than has previously
been appreciated. After starting to
routinely ask about hot tub use in
patients with generalized dermatitis,
the authors identified six patients
over a period of 12 months, despite
there only being two reported cases
in the medical literature. The authors
suspect that allergy to PPMS has
been underdiagnosed, as neither
PPMS or ammonium persulfate are
typically used when patch testing
patients with widespread dermatitis.
Pool and hot tub water treatment
consists of a two-step process: (1)
sanitation and (2) oxidation
(“shocking”). Sanitation is the process
by which pathogenic micro-organisms
are killed, and is typically
accomplished by a chlorine or
bromine donor added to the water.
Oxidation is the process by which
organic contaminants, such as
perspiration, body oils, and cosmetic
products, as well as material
introduced to the water from the
outdoors, are eliminated. Oxidation
also removes chloramines/
bromamines, which are irritating
compounds produced when
chlorine/bromine reacts with organic
contaminants in the pool water. In
pools and hot tubs in which sodium
bromide or bromine tablets (BCDHM)
are used for sanitation, PPMS also
acts to activate the bromine sanitizer.
Shocking with PPMS is recommended
weekly for pools and with every use
for hot tubs.
The authors strongly recommend
that all patients with generalized
dermatitis be asked about hot tub
and swimming pool use. It is even
more important to ask about hot tub
and swimming pool use if the patient
is a man between the ages of 45 and
80, as this is the demographic at
highest risk. If the patient reports
using a hot tub, then patch testing
with ammonium persulfate (APS),
which is available from all major
allergen suppliers, should be
undertaken. If patch testing is
positive, then the patient should be
instructed to avoid exposure to hot
tubs and swimming pools treated
with PPMS-based shock treatments.
Alternatives are to use
hyperchlorination-based shock
treatment or hydrogen-peroxide-
based shock treatment, or to drain
and refill the hot tub periodically
instead of shocking it.
If patch testing with APS is not
Figure 1. Severe dermatitis on the lower legs in a patient with allergy to potassi-
um peroxymonosulfate who sat with legs “dangling” in the water
[February 2010 • Volume 3 • Number 2]
available, then the patient should be
instructed to completely avoid hot tub
and swimming pool exposure for a
period of at least two months. If their
dermatitis improves, then they should
either continue to avoid PPMS by
using one of the methods noted above
or they could confirm the allergy by
challenging themselves with re-
exposure to PPMS and observing for a
flare of their dermatitis.
The authors do not have an
explanation for why men are more
likely to be affected. Perhaps they
spend more time in hot tubs or are
more likely to handle the chemicals
as part of maintaining hot tubs. Or
perhaps there is an unexpected
explanation that is yet to be
In summary, allergy to PPMS
used in hot tubs and swimming
pools appears to be much more
common than previously known.
Patients with the highest risk are
men between the ages of 45 and 80.
This is a relatively easily
identifiable cause of widespread,
recalcitrant, severe dermatitis, and
all patients presenting with this
picture should be questioned about
hot tub use.
1. Kagen HH, Wolf J, Scheman A,
Nedorost S. Potassium
peroxymonosulfate-induced contact
dermatitis. Contact Dermatitis.
2. Estrada Rodriguez JL, Gozalo
Reques F, Cechini Fernandez C,
Rodriguez Prieto MA. Contact
urticaria to potassium persulfate.
Contact Dermatitis. 2001;45:177.
3. Veien N, Hattel T, Laurberg G.
Contact dermatitis due to
potassium persulfate. Contact
Dermatitis. 2001;45:176.
4. Yankura JA, Marks JG Jr, Anderson
BE, Adams D. Spa contact dermatitis.
Dermatitis. 2008;19:100–101.
5. Wallengren J, Bergendorff O.
Potassium peroxymonosuflate-
induced dermatitis in a sheep
farmer. Contact Dermatitis.
6. DuPont Oxone®monopersulfate
compound technical information.
Authors: Dr. Zirwas is Assistant Professor of Dermatology, The Ohio State University, Columbus, Ohio. Ms.
Gilligan is from The Ohio State University College of Medicine. Mr. Vander Horst is from the Department of
Education—Quantitative Section, The Ohio State University, Columbus, Ohio. The authors report no relevant
conflicts of interest.
TABLE 1. Characteristics of reported patients with allergy to PPMS used as a shock treatment in hot tubs
159 M4–5 years Axillae, abdomen,
thighs, flanks, ankles Yes No 1+ 2+ Hot tub
253 M1 year Legs, trunk, arms Yes No 1+ 2+ Hot tub
360 M4 months Axillae, flanks, thighs,
calves Yes No 1+ 2+ Hot tub
449 M15 months Calves, thighs, chest,
abdomen Yes No 1+ 2+ Hot tub
554 M14 months Back, thighs, axillae Yes No 1+ 2+ Hot tub
677 M1 year Face, chest, arms,
legs Yes No Not done 2–3+ Swimming
755 M1 year Anterior legs, thighs,
torso Yes No 1+ Negative Hot tub
845 M 1 year Trunk, extremities Yes Unknown Not done 2+ Hot tub
Allergic contact dermatitis (ACD) is an important diagnosis to consider in patients with dermatitis following specific exposures. Classically, ACD from persulfates is associated with hair-bleaching products and spa water/swimming pool exposure and is most commonly reported in adult men. We report a case of ACD to potassium peroxymonopersulfate (PPMS), a common pool "shocking" chemical, in a 7-year-old boy presenting with recurrent and diffuse dermatitis triggered by swimming pool exposure.
Background: Persulfate is an oxidizing agent used for multiple purposes, including bleaching hair, bleaching flour, and as pool/spa water disinfectant. Objective: To identify the prevalence and clinical characteristics of patients allergic to ammonium persulfate (APS) among patients who underwent patch testing in our clinic. Methods: A retrospective chart review of 2138 patients who underwent patch testing at Brigham and Women's hospital in Boston between July 2015 to November 2019. All patients were tested to our standard series including APS 2.5% petrolatum. Given the irritant nature of APS, we included for analysis only patients with 2+ or 3+ reactions. Results: Among 2138 patients, 61 (2.85%) had 2+ or 3+ reactions to APS. In this study, 72% were female. 75% had an atopic diathesis; 56% had 2+ reactions, and 44% had 3+ reactions. Clinical relevance was definite in 11%, probable in 10%, and unknown/possible in 79%. In patients with definite clinical relevance, 6/7 had occupational allergic contact dermatitis: 4 hairdressers, 1 hair salon cleaner, and 1 aquarium worker; 1/7 was bleaching her hair. Conclusion: Prevalence of 2+ or 3+ APS reactions in this single-center study was higher than that reported by the North American Contact Dermatitis Group, 2015-2016, (0.75% vs. 2.85% in our study). APS is an important occupational allergen, and clinicians should be aware of this when treating patients with exposure to APS.
Background Persulfate compounds are reactive oxidative agents increasingly recognized as contact allergens. Objective The aim of this study was to identify common consumer products containing persulfate compounds in the United States market. Methods Five publicly accessible online ingredient repositories and searches of two large online retailers were used to identify persulfate-containing consumer products. Results We identified persulfates in 23 hair coloring products, 11 denture cleansers, 8 pool/hot-tub products, 3 paints, and 3 cleaning products. Conclusions Clinicians assessing contact dermatitis should be aware of three primary categories of consumer products that contain persulfates: denture cleansers, hair coloring products, and non-chlorine hot-tub and pool shock. This article is protected by copyright. All rights reserved.
Background: Ammonium persulfate (APS), an oxidizing agent used in hair products, manufacturing, and pool/spa water, can cause skin reactions including allergic contact dermatitis. Objective: To characterize positive patch test reactions to APS (2.5% pet). Methods: Retrospective analysis of patients tested to the North American Contact Dermatitis Group (NACDG) screening series from 2015-2018. Results: Of 10,526 patients, 193 (1.8%) had positive patch test reactions to APS. Compared to negative patients, APS-positive patients were significantly more likely to be male (43.2% vs. 28.0%, p<0.0001), have primary hand (30.2% vs. 22.0%, p=0.0064), scattered generalized (25.5% vs. 17.9%, p=0.0064), or trunk dermatitis (8.9% vs. 4.9%, p=0.0123), and occupationally-related dermatitis (22.2% vs. 10.9%, p<0.0001). Over half of the APS-positive reactions were currently relevant (57.0%); 19 (9.8%) were related to occupation, especially (68.4%) hairdressers. Swimming pools/spas (23.3%) and hair care products (19.2%) were the most common APS sources. Limitations: Immediate reactions and follow-up testing not captured. Conclusions: The proportion of patients positive to APS was 1.8%. APS positivity was significantly associated with male sex and hand dermatitis. Swimming pool/spa chemicals are important sources of APS exposure.
The International Contact Dermatitis Research Group proposes a classification for the clinical presentation of contact allergy. The classification is based primarily on the mode of clinical presentation. The categories are direct exposure/contact dermatitis, mimicking or exacerbation of preexisting eczema, multifactorial dermatitis including allergic contact dermatitis, by proxy, mimicking angioedema, airborne contact dermatitis, photo-induced contact dermatitis, systemic contact dermatitis, noneczematous contact dermatitis, contact urticaria, protein contact dermatitis, respiratory/mucosal symptoms, oral contact dermatitis, erythroderma/exfoliative dermatitis, minor forms of presentation, and extracutaneous manifestations.
Keywords:potassium persulfate;contact urticaria;cosmetics;hair dyes
Keywords:potassium persulfate;allergic contact dermatitis;occupational;laboratory worker;potato flour;cross-sensitivity;ammonium persulfate
Potassium monopersulfate (MPS) is widely used in spa and pool "shock" treatments, yet contact dermatitis associated with MPS has been rarely reported. A patient presented with a generalized scattered dermatitis from the neck down that worsened after spa use. Patch testing elicited a ++ reaction to ammonium persulfate. Contact with ammonium persulfate was ruled out; however, MPS, which can cross-react with ammonium persulfate, was found to be the active ingredient in the patient's spa shock treatments. The dermatitis cleared after the patient switched to a hydrogen peroxide-based shock treatment.