An unusual cause of lip swelling

Recurrent lip swelling is a frequent presentation to Oral Medicine with causes including orofacial granulomatosis, allergic angioedema, and hereditary angioedema. We present a case of lip swelling associated with stannous fluoride allergy.

A 19-year-old woman presented with a 6-month history of episodic lip swelling and crusting. She described episodes of symmetrical upper and lower lip swelling, presenting over several hours, accompanied by crusting and dryness. The swelling persisted for up to 3 days with complete resolution between episodes. The patient noted possible triggers including a new toothpaste, Oral B Gum & Enamel Pro-Repair, the ingredients of which include sodium lauryl sulfate, stannous chloride, stannous fluoride and sodium fluoride.

The patient attended for patch testing to the extended European baseline series of contact allergens. She was also asked to perform a repeated open application test (ROAT) with daily topical application of her Oral B toothpaste to the skin of the arm. Her day 2 and 7 patch readings demonstrated a vesicular reaction (+++) to tin oxalate. Her ROAT demonstrated perifollicular erythema at day 2 and a florid papular reaction at day 7. The toothpaste, and other toothpastes containing stannous (tin) fluoride, were withdrawn, with no recurrence of lip swelling since.

This case demonstrates allergic contact cheilitis associated with tin present in toothpaste in the form of stannous fluoride and chloride. Metals are commonly associated with allergic contact dermatitis, and contact allergy to components of amalgam, namely mercury, are commonly encountered in Oral Medicine clinics in the form of oral lichenoid lesions. Tin is much less frequently encountered as an oral allergen, with only a few reported cases1,2 and a case series of 34 toothpaste allergies identifying stannous fluoride as the causative allergen in a single case only3.