Hypersensitivity reaction of the gingiva to chlorhexidine: case report and literature review

Objective. The aim of this case report was to document a case of delayed-type hypersensitivity reaction of the gingiva to chlorhexidine and review the literature on oral mucosal hypersensitivity reactions associated to chlorhexidine-containing oral hygiene products. Study Design. A 58-year-old man presented with a well-demarcated erythematous area on the right upper anterior gingiva. Incisional biopsy was performed. Postoperatively, chlorhexidine digluconate gel was prescribed twice a day, but the patient did not use it because he experienced intense burning immediately after the first application. The microscopic diagnosis was nonspecific mucositis. Hypersensitivity reaction was suspected. The patient reported use of 0.004% chlorhexidine digluconate-based toothpaste twice a day in the past few years. A delayed-type hypersensitivity reaction to the toothpaste was hypothesized, and its use was discontinued. Chlorhexidine, the common ingredient of both the toothpaste and the gel, was considered the allergen. The literature was reviewed on chlorhexidine-induced oral hypersensitivity reactions. Results. Two weeks after cessation of toothpaste use, complete remission of the lesion was observed without additional intervention. Four years later, no recurrence has been reported. The literature review yielded 7 studies reporting 20 patients with intraoral manifestations of hypersensitivity reactions associated with chlorhexidine-containing oral hygiene products. Conclusions. Clinicians should be aware that oral hygiene products containing even low concentrations of chlorhexidine might induce hypersensitivity reactions.