When cosmetic allergy is suspected, it is essential to include the personal care products used by the patient in the patch tests as not only will this facilitate a more exact diagnosis, but also it may make it possible to identify new allergens. The collaboration of the pharmaceutical and cosmetics industries is fundamental to this approach, as it is those companies that will have to supply us with the components of the specific products. We present a case of allergic contact dermatitis to capryloyl salicylic acid present in an antiwrinkle cream. A 40-year-old woman consulted for a pruritic erythematous rash that arose on her face 10 days after starting to apply an antiwrinkle cream (Revitalift Laser X3 Day Cream by L’Oreal). The condition resolved after interruption of the use of the cream and a week of treatment with a topical corticosteroid. Patch testing was performed using the standard series of the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC), a cosmetics series (Chemotechnique, Sweden), and the specific cream used by the patient, with readings taken at 48 and 96hours, in accordance with the recommendations of the European Society of Contact Dermatitis (ESCD). In the final reading at 96hours, a positive reaction (++) was observed to the specific cream used by the patient and negative reactions to the other allergens in the standard and cosmetics series. We contacted the company that marketed the cream involved and they provided us with the 27 ingredients of the cream, thus enabling us to complete the study. A positive allergic reaction (++) to 1% capryloyl salicylic acid in alcohol was observed in the readings taken at 48 and 96hours (Fig. 1). This same substance showed no allergic responses after patch testing in 15 healthy controls.

Figure 1.

Positive allergic reaction to capryloyl salicylic acid.

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Capryloyl salicylic acid (5-capryloyl salicylic acid, CAS no. 78418-01-6, also known as 2-hydroxy-5-octanoylbenzoic acid) is a lipophilic derivative of salicylic acid that promotes epidermal renewal, stimulates collagen formation, combats chronic actinic photodamage,1 and increases skin resilience to UV radiation. It is attributed comedolytic,2 antiacne,3 antibacterial, and anti-inflammatory4 properties. This substance is widely used, mainly by the French cosmetics industry, and it can be included in facial emollients, antiaging formulations, products for the treatment of acne, sunscreens, and facial hygiene products.5

De Groot et al.5 recently published the first 2 cases of contact allergy to capryloyl salicylic acid, using 1% capryloyl salicylic acid in alcohol in the patch testing of their patients. According to those authors, the allergenicity of this substance may derive more from the salicylic or benzoic part of the molecule that from the caprylic acid fraction. However, Roberts et al.6 concluded that 5-capryloyl salicylic acid was probably not the agent responsible for the allergy of the patients described by de Groot et al.; in their opinion, the allergy was due to its 3-capryloyl salicylic acid isomer, a contaminant of 5-capryloyl salicylic acid.

We have described a third case of allergic contact dermatitis to capryloyl salicylic acid, the diagnosis of which was made possible by patch testing the ingredients provided by the company marketing the cream used by the patient, as these substances are not included in other test series. The description of further cases in which capryloyl salicylic acid is implicated will clarify the allergenic potential of this substance.