Sep 12, 2019
Household and personal care products are common sources of
contact allergy in dermatology patients. Dr. Vincent DeLeo talks
with Dr. Amber Atwater and Dr. Margo Reeder and about the epidemic
of allergic contact dermatitis associated with
methylisothiazolinone (MI), a common preservative found in many
water-based products. Dr. Reeder and Dr. Atwater discuss the
emergence of MI as a contact allergen and highlight some of the
common and lesser-known sources of MI exposure.
We also bring you the latest in dermatology news and
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those with severe skin sagging.
New evidence supports immune system involvement in hidradenitis
Microscopy identifies signs of immune dysregulation in the blood
of hidradenitis suppurativa patients.
3. Dr. Andrew Alexis discusses topical treatment options
for pigmentary disorders
Things you will learn in this episode:
- Methylisothiazolinone (MI) has been used for decades as a
preservative in combination with methylchloroisothiazolinone;
however, higher concentrations of MI alone have been used in
personal care products beginning in the 2000s: “That’s really when
we began to see patients being exposed to MI and subsequently
developing contact allergy,” notes Dr. Reeder.
- Common sources of MI exposure include liquid and water-based
products such as dish soaps, shampoos, household cleaners, hair
conditioners and dyes, laundry products, and soaps and
- Latex-based paints containing MI can result in airborne contact
dermatitis from off-gassing when the paint is curing on the
- Another common source of MI contact dermatitis is slime, a
sticky play substance that children concoct out of household
products such as glue or cleaning agents that contain MI.
- Contact allergy to MI may present in a photodistributed pattern
and also has been associated with photoaggravation. Patients also
may demonstrate lasting photosensitivity even when avoiding the
allergen; therefore, it is important to consider including MI when
performing photopatch testing.
- Two additional potentially allergenic isothiazolinones found in
household products and industrial chemicals include
benzisothiazolinone and octylisothiazolinone.
- The T.R.U.E. Test includes MI in a mix with
methylchloroisothiazolinone but not on its own, which has been
known to miss a considerable number of patients who are allergic to
MI; therefore, patch testing to MI alone may be beneficial in
patients with allergic contact dermatitis who test negative for MI
contact allergy using the T.R.U.E. Test.
- Many patients are sensitized to MI when it is used in leave-on
products. The European Union has banned MI from use in these
products, but currently there are no regulations in the United
Hosts: Elizabeth Mechcatie, Terry Rudd, Vincent A. DeLeo, MD (Keck
School of Medicine of the University of Southern California, Los
Guests: Margo Reeder, MD (University of Wisconsin, Madison);
Amber Reck Atwater, MD (Duke University, Durham, North
Carolina); Andrew F. Alexis, MD, MPH (Icahn School of Medicine
at Mount Sinai, New York.
Show notes by Alicia Sonners, Melissa Sears, and Elizabeth
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