D2.65 - Allergic cheilitis related to vaginal lubricant: a case report

Background: Glycols, particularly propylene glycol (PG), are commonly used as emollients and humectants in vaginal lubricants and moisturizers and play a key role in determining their osmolality. Although PG is generally considered a weak sensitizer, allergic contact dermatitis related to its use in vaginal lubricants remains rare. To date, only three cases have been reported in the literature.

Case Presentation: We report the case of a 28-year-old female student with no significant past medical history, who presented to the dermatology and allergology unit of the occupational medicine department for evaluation of a chronic, painful, and disabling erosive cheilitis evolving in recurrent flare-ups over a six-month period. The patient had no personal or family history of atopy. A comprehensive diagnostic work-up was conducted, including autoimmune, infectious, and inflammatory investigations. Infectious cheilitis, atopic cheilitis, drug-induced eruptions, and autoimmune bullous diseases were systematically excluded, leading to a strong suspicion of allergic contact cheilitis.

Diagnostic Assessment: Patch testing using the European baseline series yielded negative results. Additional patch tests with products routinely handled by the patient (cosmetics, detergents, and cleaning agents) were performed to exclude hand-transmitted allergic contact dermatitis and were also negative. Given the clinical context, food allergy was considered, but skin prick tests were negative. A second, more detailed anamnesis focusing on lifestyle and sexual practices revealed a history of oral sexual contact. The vaginal lubricant used by the patient to treat vaginal dryness was subsequently suspected as the source of sensitization. Patch testing with the lubricant was positive (++), and further analysis of its composition identified propylene glycol as the causative allergen.

Conclusion: This case highlights propylene glycol as a potential cause of allergic contact cheilitis. It underscores the importance of detailed patient history, including sexual practices, and careful evaluation of excipients in personal care products. Clinicians should maintain a high index of suspicion for PG-induced allergic contact dermatitis and advocate for greater transparency regarding excipient composition in topical and mucosal products.