Sulfites Selected as Allergen of the Year

Sulfites, present in foods, drinks, pharmaceuticals, and personal care products, have been named the "Allergen of the Year" for 2024 by the American Contact Dermatitis Society (ACDS).

Sulfites are currently not found in most screening patch test series, so may be missed as a relevant contact allergen, Donald V. Belsito, MD, emeritus professor in the Department of Dermatology at Columbia University, New York City, said in his presentation on the Allergen of the Year on March 7 at the ACDS Annual Meeting in San Diego. Sulfites, he noted, are distinct from sulfates, and the groups do not cross-react with each other.

Sodium disulfite, an inorganic compound, belongs to a group of sulfiting agents, which contain the sulfite ion SO32− and include ammonium sulfite, potassium sulfite, and sodium sulfite, Belsito said. Sulfites function as antioxidants and preservatives in a range of products including food and beverages, personal care products, and pharmaceuticals.

The type of sulfite allergy diagnosed by patch testing is type IV hypersensitivity or delayed-type hypersensitivity, where patients present with pruritic, red, scaling macules, papulovesicles, and patches, Belsito told Medscape Medical News. "It is not the type I, immediate hypersensitivity that causes hives and, in some cases, anaphylaxis," he said. Sulfites also can cause these side effects, so correct labeling of food and beverages is important, he noted.

Some common nonoccupational sulfite sources include hair coloring and bleach products, hairspray, tanning lotions, makeup, sunscreens, and deodorants, Belsito said in his presentation. Medications including topical antifungals, topical corticosteroids, and nasal solutions can be culprits, as can water in swimming pools, he noted.


In occupational settings, sulfites may be present not only in food and drink products but also can be used in production of products, such as those used for sterilization during beer and wine fermentation, Belsito said in his presentation. Other potential occupational sources of sulfite exposure include healthcare settings and textile, chemical, rubber, and pharmaceutical manufacturing.

High-sulfite food products (> 100 ppm) to be aware of include dried fruit (raisins and prunes are exceptions), bottled lemon or lime juice (but not frozen products), wine, molasses, grape juice (white, or white, pink, and red sparkling), and pickled cocktail onions, Belsito said.

"Like other contact allergens, the clinical presentation correlates with exposure," he added. A study by the North American Contact Dermatitis Group (NACDG) found that 28.8% of patients positive for sulfite allergy on patch testing presented with facial dermatitis, which was not only related to cosmetics and medications used on the face but also from products, such as shampoo, used on the scalp that dripped onto the face. "The scalp is relatively resistant to the expression of contact allergy and may not be involved at all," he said.

According to the NACDG study, the hands were the second most common site of dermatitis associated with sulfites (20.5%) followed by generalized distribution (13.6%). These sites are to be expected, given the sources of food and beverage, personal care products, and occupational materials, Belsito said.

"Eczematous dermatitis of the lips is also common in patients with ingested food sources of sulfites," he said.

Systemic contact dermatitis to sulfites has been documented following oral, rectal, and parental exposure, Belsito told Medscape Medical News. "Systemic dermatitis may present as a scattered/generalized dermatitis, symmetrical drug-related intertriginous and flexural exanthema (also referred to as baboon syndrome), or erythroderma," he said.

How to Spot Sulfite Allergies

The exclusion of sulfites from most patch test series means that sulfite allergy diagnoses are often missed, despite the wide range of potential exposures, Belsito said.

"Most cases of allergic contact dermatitis occur at the site of application of the allergen," he told Medscape Medical News. Depending on the location of the dermatitis, a detailed history of exposures that includes cosmetics and topical medications, work-related materials, and foods and beverages might suggest a sulfite allergy, he said.

Given the range of potential clinical presentations and the many and varied exposures to sulfites, Belsito's best tip for clinicians is to routinely screen for them and evaluate the many avenues of exposure if a patch test is positive, he said.

For now, Belsito said he does not think additional research is needed on sulfites as allergens; instead, sulfites, such as sodium metabisulfite/sodium disulfite, should be included in all clinicians' baseline screening series, he said.

The Allergen of the Year was also recently announced in the journal Dermatitis. Authors Samuel F. Ekstein, MS, and Erin M. Warshaw, MD, from the Department of Dermatology, Park Nicollet Health Services, Minneapolis, Minnesota, noted that the ACDS hoped to raise awareness of sulfites as a "significant allergen" and called for their increased inclusion in screening patch test series.

Patients identified with sulfite allergies can find alternative products on the ACDS CAMP (Contact Allergen Management Program) website, Warshaw said in an interview.

Warshaw also highlighted some examples of sulfites as allergens in healthcare settings in particular. She described one patient who presented with dermatitis at the site of three previous hand orthopedic procedures.

"Although surgical cleansers were suspected, 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," she said. Another patient who had been treated for recurrent otitis externa and seborrheic dermatitis was found to be allergic to sulfites in an otic antibiotic suspension as well as in a ketoconazole cream product, she added.

In the paper, Warshaw and Ekstein called for the addition of sulfites to the test series. Although the NACDG added sodium metabisulfite to the series in 2017, sulfites are not part of the American Contact Dermatitis Core Series, they wrote. Sodium metabisulfite, they added, was added to the European baseline standard series after review of the 2019-2020 patch test reactivity and clinical relevance data.

The ACDS meeting is held every year the day before the annual meeting of the American Academy of Dermatology.

Article from Medscape.


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