Excipients in Oral Antihistamines Can Perpetuate Allergic Contact Dermatitis.

Propylene glycol is a well-documented causative agent of allergic contact dermatitis (ACD). It is also reported to cause systemic dermatitis after ingestion of foods or medicines containing it and after intravenous injection of a medicine with propylene glycol in its base. We describe two adolescents with sensitivity to propylene glycol confirmed by patch testing whose dermatitis improved dramatically after cessation of oral antihistamines containing propylene glycol. We report these cases to alert providers to the potential for worsening of ACD due to systemic exposure to propylene glycol in patients with a cutaneous sensitivity to the allergen.

Contact allergens in oral antihistamines.

BACKGROUND: Excipients in various formulations of active drugs occasionally include known contact allergens. Their ingestion may trigger dermatitis or cause it to become widespread or refractory to therapy. OBJECTIVE: The aim of this study was to investigate the prevalence of common contact allergens among the excipients of oral antihistamines available in this country. METHODS: We gathered the complete ingredient lists of 2119 different preparations of 12 oral antihistamines from the National Library of Medicine data bank and entered them into an electronic database for analysis. RESULTS: More than half the formulations (55.0%) contained at least 1 member of the 10 allergen families assessed. Most brompheniramine and doxepin preparations included potentially allergenic excipients, whereas fexofenadine was most often free of them. Sorbitan group members, azo dyes, and propylene glycol were the allergens found most frequently in the antihistamines, each present in over 25% of the products. Elixirs, liquids, solutions, suspensions, and syrups were more likely than nonchewable caplets, capsules, and tablets to contain the allergens tabulated (100% vs 39.3%, respectively). Chewable pills frequently contained azo dyes. CONCLUSIONS: Ingestion of antihistamines could precipitate a systemic contact dermatitis in a patient sensitized to an allergen present as an excipient in the medicine.

Chlorhexidine: uses and adverse reactions.

Chlorhexidine is increasingly being used not only as an antiseptic to prevent hospital infections and an adjuvant in oral hygiene but also as a preservative in personal care products. As exposure to the agent becomes more widespread, reports of adverse reactions to it are increasing. Complications range from mild irritant contact dermatitis to life-threatening anaphylaxis. Allergic contact dermatitis in some cases precedes anaphylaxis. It is imperative that physicians be aware of the many possible sources of contact with this antiseptic and be alert to recognize the potentially debilitating and catastrophic reactions that may occur because of chlorhexidine sensitization.

Pruritus ani as a manifestation of systemic contact dermatitis: resolution with dietary nickel restriction.

Pruritus ani is a common distressing problem with numerous possible causes. When locally applied agents trigger irritation or allergic response, skin changes of dermatitis usually accompany the itch. Focal pruritus in the absence of dermatitis is not generally considered to be a manifestation of contact allergy. Furthermore, focal pruritus is not listed among the possible diverse presentations of the systemic delivery of a proven contact allergen. We report a case of a gentleman with a 1.5-year history of treatment-resistant pruritus ani. When patch testing revealed a positive reaction to nickel sulfate, he admitted to daily peanut butter consumption. His symptoms resolved with dietary nickel restriction. Patch testing may be useful in patients with pruritus of the anogenital region, not only to elucidate potential contact exposures contributing to the symptom but also to suggest possible dietary precipitants.