2024 Allergen of the year: Sulfites
Clinical Applications
Dr. Schwarzenberger is the former physician editor of DermWorld. She interviews the author of a recent study each month.
By Kathryn Schwarzenberger, MD, FAAD, April 1, 2024
In this month’s Clinical Applications column, DermWorld Physician Editor Kathryn Schwarzenberger, MD, FAAD, talks with Erin Warshaw, MD, FAAD, about her Dermatitis paper, ‘Sulfites: Allergen of the Year 2024.’
DermWorld: The long-awaited Contact Allergen of the Year for 2024 is sulfites! What are sulfites and why were they chosen this year?
Sulfites were chosen as allergen of the year to raise awareness that this allergy exists and may be missed by the T.R.U.E Test, ACDS Core Series, and most “screening series.” Thus, an allergy to sulfites may be under-recognized. We also want to raise awareness of the potential sources of sulfites (including gloves!) and offer practical resources.
DermWorld: Sulfites, sulfates? Are they the same and do those with sulfite allergies need to avoid both?
Dr. Warshaw: This is a common misconception! Importantly, sulfates contain the sulfate ion (SO₄²-) and are completely different from sulfites; there is no cross-reactivity.
DermWorld: What does sulfite contact dermatitis commonly look like? Are there people at high risk of developing this allergy?
Dr. Warshaw: Sulfite contact dermatitis looks similar to contact dermatitis due to other substances. It presents as an eczematous eruption at the anatomical site of exposure. Hand, face, and lip dermatitis are common presentations. Systemic contact dermatitis distribution patterns have also been described.
There is no strong association of sulfite contact allergy with gender. Risk is higher in individuals in certain occupations and industries including brewing, wine making, photographic chemical use, leather manufacturing, the textile industry, mineral extraction, the pulp/paper industry, chemical manufacturing, rubber production, food preparation, health care, pharmaceutical/personal product production, and water/sewage treatment.
DermWorld: Where might we and our patients commonly encounter sulfites?
Dr. Warshaw: Sulfites are added to various topical medicaments, including antifungals, corticosteroids, ophthalmic solutions, hemorrhoidal preparations, local anesthetics, topical antibiotic preparations, and urinary catheterization gels. I had one patient who presented for dermatitis at the site of three hand orthopedic procedures; surgical cleansers were suspected, but the patient reacted to sodium metabisulfite. Review of the operating room contactants confirmed sulfites as preservatives in an injectable anesthetic and antibiotic (used for wound irrigation). I had another patient who had been treated for recurrent otitis externa and seborrheic dermatitis who was allergic to sulfites in the antibiotic otic suspension as well as ketoconazole cream.
Many personal care products contain sulfites including hair dyes, bleaching creams, and vaginal preparations. Safe alternatives may be found on the ACDS CAMP product website. Occupational contact dermatitis has been reported in hairdressers, food/beverage industry workers, and photographers. Sulfites are also used in the manufacturing of gloves and have been detected in both latex and nitrile gloves.
DermWorld: What about sulfites in foods? Do we need to worry about Type I hypersensitivity reactions as well?
Dr. Warshaw: Sulfites may occur naturally in food as a byproduct of fermentation or may be added as a preservative. Foods with high sulfite content include dried fruit, beer, wine, fruit/citrus juices, pickled products, bottled salad dressings, sauerkraut, and vinegar. I only advise avoidance of sulfites in food if the patient has lip dermatitis and/or a systemic contact dermatitis presentation.
Type I hypersensitivity may occur, but it is less common now than in the past. Because of many reports of severe systemic Type I reactions, in 1986, the FDA banned the use of sulfites on fresh fruits and vegetables, and packaged foods containing 10 ppm or more of sulfites are now required to disclose this on labels.
DermWorld: How do we test for sulfite allergy? Is it on the T.R.U.E. Test® panel?
Dr. Warshaw: Sodium disulfite and sodium metabisulfite are available for purchase from patch test allergen suppliers. It is not on the T.R.U.E Test nor is it on the ACDS Core Series. It will likely be added to the Core Series when updated.
DermWorld: Finally, what about wine? Many wines contain sulfites. Are wines off the menu forever?
Dr. Warshaw: Good question! It depends. If the patient has lip dermatitis or a systemic contact dermatitis presentation, then I will talk about avoidance of sulfites in food/beverages. Low-sulfite wines as well as devices (“wands”) to treat wine are marketed to individuals with sulfite “intolerance” (e.g., headaches) but there is no scientific data (to my knowledge) about tolerance of these products in patients with contact allergy.
Dr. Warshaw is a professor of dermatology at the University of Minnesota and past director of the Park Nicollet Contact Dermatitis Clinic in Bloomington, Minnesota. She also staffs occasional dermatology resident clinics at the Minneapolis VA medical center.
Co-author Dr. Sam Ekstein is an incoming dermatology resident at HonorHealth in Phoenix. Their paper appeared in Dermatitis. The authors have no relevant financial or commercial conflicts of interest.
Disclaimer: The views and opinions expressed in this article do not necessarily reflect those of DW.
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