title: Severe contact urticaria to guar gum included as gelling agent in a local anaesthetic.
abstract: We report the first case of a life-threatening immediate-type hypersensitivity caused by Dynexan, a local anaesthetic gel. After mucosal application by his dentist, a 63-year-old man rapidly developed urticaria, dyspnea and, at last, he collapsed and remained unconscious for 2 hr despite emergency care. While the standard prick tests were negative to all local anaesthetics tested including lidocaine, a 1-fold positive reaction was detected to Meyprogat 60, an ingredient of Dynexan. As the gelling agent Meyprogat represents a derivative of guar (synonymous guar gum, guaran, E-412), we subsequently tested different guar products derived from Cyamopsis tetragonoloba beans and, as control, the closely related locust bean gum E-410. In the prick-to-prick tests, the guar-derived food additive Provigel NAG 905 provoked a 1-fold positive reaction. Native guar beans pounded and resuspended in water showed a 2-fold positive reaction, whereas no reaction was found to derivatives of locust bean gum. Specific immunoglobulin E were negative in all cases. Despite the common use of guar as versatile food additive or gelling agent, this is the first case of a severe immediate-type hypersensitivity after mucosal contact.
authors.affiliation: Department of Dermatology, University of Regensburg, Franz-Josef Strauss-Allee 11, D-93053 Regensburg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Roesch
authors.forename: Till
authors.initials: T
authors.lastname: Haegele
authors.forename: Thomas
authors.initials: T
authors.lastname: Vogt
authors.forename: Philipp
authors.initials: P
authors.lastname: Babilas
authors.forename: Michael
authors.initials: M
authors.lastname: Landthaler
authors.forename: Rolf-Markus
authors.initials: RM
authors.lastname: Szeimies
mesh_terms: D000707:Anaphylaxis / Q000139:chemically induced / Q000175:diagnosis* / Q000628:therapy; D000779:Anesthetics, Local / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology / Q000628:therapy; D003937:Diagnosis, Differential; D004638:Emergency Treatment; D005685:Galactans / Q000009:adverse effects*; D005782:Gels / Q000009:adverse effects; D006801:Humans; D007428:Intradermal Tests; D008297:Male; D008351:Mannans / Q000009:adverse effects*; D008875:Middle Aged; D053149:Plant Gums; D012720:Severity of Illness Index
chemical_list: D000779:Anesthetics, Local; D005685:Galactans; D005782:Gels; D008351:Mannans; D053149:Plant Gums; C007894:guar gum