Case of allergic contact dermatitis due to 1,3‐butylene glycol

1,3‐Butylene glycol (1,3‐BG) is widely used in cosmetics, including low‐irritant skin care products and topical medicaments, as an excellent and low‐irritation humectant. We report a case of allergic contact dermatitis caused by 1,3‐BG. A 28‐year‐old woman suffered from an itchy erythematous eruption on her face. By 2 days of closed patch testing, her own cosmetics and many of the hypo‐irritant skin care products showed positive results. A second patch testing showed positive reaction to 1,3‐BG (1% and 5%). 1,3‐BG was a common component in most of the products that had elicited a positive reaction in the first patch testing. Although allergic contact dermatitis due to 1,3‐BG is not so common, we have to consider 1,3‐BG as a possible contact allergen in the patients presenting with allergic contact dermatitis due to various cosmetics.