CD04 Are we missing toothpaste allergens in allergic contact cheilitis and oral mucosal disease?

Abstract

Toothpastes are a recognized cause of allergic contact cheilitis and oral mucosal disease, traditionally attributed to flavouring agents. Increasing use of stannous (tin) salts in toothpaste formulations may represent under-recognized allergens. There is currently no dedicated British Society for Cutaneous Allergy (BSCA) cheilitis or oral mucosal patch test series. We reviewed reported cases of toothpaste-induced allergic contact cheilitis and correlated reported allergens with current toothpaste ingredients, to provide evidence supporting a BSCA multicentre cheilitis audit and development of a dedicated patch test series. A literature review was conducted using PubMed in January 2026 with the search terms toothpaste, allergic, allergy, contact dermatitis, contact cheilitis, lichenoid and stomatitis. Non-English-language publications and reports lacking sufficient clinical or diagnostic detail were excluded. Published cases were analysed alongside contemporary UK toothpaste ingredient prevalence data (Phillips PF, Rogers A, Soriano LF. Mint condition? A survey of allergenic ingredients in UK toothpastes. Clin Exp Dermatol 2026; in press; doi: 10.1093/ced/llag006). Between 1932 and 2025, 232 cases of toothpaste-related allergy were identified, with 130 patients testing positive to their own toothpaste. Flavourings were the most frequently implicated allergens (n = 133), particularly cinnamon derivatives (n = 63), menthol compounds including peppermint and carvone (n = 37), anethole (n = 12) and eugenol (n = 7). Despite this, cinnamon derivatives are currently labelled in only 5.9% of UK toothpastes, with no published cases since 1998. In contrast, stannous fluoride and stannous chloride, present in 7.3% and 3.5% of UK toothpastes, respectively, have been implicated in nine published cases of cheilitis, all since 2014, suggesting a shift in clinically relevant exposures. These findings demonstrate that while several toothpaste flavour allergens are captured within recommended BSCA baseline, fragrance and facial series, increasingly prevalent ingredients, particularly stannous salts, and flavourings such as anethole, remain unrepresented. This provides a clear rationale for a BSCA multicentre cheilitis audit and the development of a dedicated cheilitis patch test series reflecting contemporary toothpaste exposures.