Allergic paraben and benzyl alcohol hypersensitivity relationship of the “delayed” and “immediate” varieties

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Abstract
From a review of the literature, and the results of scratch, intracutaneous and subcutaneous injections of patients with parabens and benzyl alcohol sensitivity of the delayed type characterised by allergic contact dermatitis and strongly positive patch tests, it would appear that such sensitivity is not usually accompanied by the immediate urticarial type of allergic sensitivity. This communication concerns itself with results of testing patients with clinical sensitivity and positive patch test reactions to the parabens or benzyl alcohol with scratch, intracutaneous and subcutaneous injections of these preservatives in order to determine the relationship of the “delayed” type of allergic hypersensitivity to the parabens and benzyl alcohol with the “immediate” variety of hypersensitivity. The parabens and benzyl alcohol are widely employed as preservatives for many allergenic extracts used in scratch and intracutaneous testing. In addition, these preservatives are used in injectable corticosteroid medicaments and in local anesthetic solutions. In order to determine whether the presence of these preservatives in allergenic extracts would produce false positive scratch or intracutaneous tests or might produce an immediate, urticarial or anaphylactic reaction in patients with allergic contact dermatitis and positive patch test reactions to these preservatives, two patients with positive patch test reactions and allergic contact dermatitis to the parabens and two with similar benzyl alcohol sensitivity were tested in the manner detailed in the following case reports.