There are few prior reports of ACD due to beer. A case series in 1969 described 4 patients with positive patch testing to ethanol and alcohol by-products and clinical resolution with avoidance of alcohol.8 Another case from 1985 described ACD to beer where patch testing was positive to the beer itself.9 Other published cases of cutaneous reactions to beer demonstrated immediate-type hypersensitivity resulting from both ingestion and skin contact, which is thought to be caused by IgE antibodies to malt and barley proteins.10,11
It is important to distinguish between systemic ACD and oral allergy syndrome (OAS). Although the defining features and criteria for diagnosing OAS have not been officially established, OAS is an IgE-mediated immune reaction commonly described as itching, tingling, or swelling, usually confined to the oral cavity after recent consumption of foods such as raw fruits, vegetables, and nuts.12 Oral allergy syndrome is treated with antihistamines and avoidance of known food allergens. In comparison, ACD is a type IV hypersensitivity, delayed cell-mediated reaction, commonly presenting with widespread rash.
Occupational contact dermatitis is common in bakers and food handlers and is more often irritant than allergic. Several relevant allergens have been identified in these groups13,14 and do not include sorbitans; our patient tested positive to both SSO and SMO. Sorbitan sesquioleate and SMO have been increasingly recognized as contact allergens over the last several years, both as standalone allergens and as potential cross-reactors.1 Sorbitan sesquioleate, SMO, and other sorbitol derivatives are found in cosmetics, topical and oral medications, topical emollients, produce, and other commercial products, including but not limited to topical clindamycin, topical metronidazole, topical ketoconazole, tazarotene cream 0.05% and 0.1%, toothpastes, acetaminophen maximum strength liquid, apples, berries, and sucrose-free cakes and cookies.1,15,16
In 2014, a study evaluated 12 oral antihistamines as potential sources for systemic contact allergens; 55% of these 12 oral antihistamine preparations included at least 1 of 10 allergen groups specifically identified. The sorbitans and sorbitol derivatives group ranked highest among the group of allergens found listed in these oral medications.17
Most patients found to have a contact allergy to the products containing SSO, SMO, or sorbitol derivatives reported notable improvement with discontinuation and change to sorbitol-free product use.1,18 It should be noted that SSO is added as an emulsifier to many of the fragrances used for patch testing. A positive patch test to fragrance mix without concomitant sorbitan testing may incorrectly diagnose the allergen.19
Patients with atopic dermatitis, particularly those with a filaggrin mutation, are at increased risk for ACD to sorbitans due to a compromised skin barrier and frequent use of topical steroids. In one study, 75% of patients (n=12) with a positive patch test to SSO were using a topical steroid emulsified with sorbitol or sorbitan derivatives.19
Sorbitan sesquioleate and SMO are increasingly relevant contact allergens. Sorbitol and related substances have been identified in numerous products and may be present in yeast-fermented and leavened goods. When patch testing is positive to SSO and SMO, the dermatologist should inquire about dietary habits with specific attention to beer and bread, in addition to inventorying other dietary preferences, prescription and over-the-counter medications, and personal care products. We suggest dietary considerations only if topical exposures have been eliminated and the rash has not improved.