Cheilitis and urticaria associated with stannous fluoride in toothpaste
Authors: Monica Enamandram, Shinjita Das, Keri S. Chaney
Journal: Journal of the American Academy of Dermatology (2014)

To the Editor: A 55-year-old woman presented with recurrent idiopathic urticaria and cheilitis. Her symptoms began 2 years ago following dental work, with intermittent lip swelling and daily hives occurring over 10 months. She received 5- to 7-day tapered courses of 40 mg prednisone on 8 occasions during this time, and her symptoms ultimately remitted spontaneously. Prior allergy workup for urticaria, including patch testing (via TRUE test) was mildly positive only for thimerosal and fragrance. Prick testing for environmental allergens was negative. One month before initial evaluation, the patient underwent implantation of new dental resin fillings in place of older amalgam fillings. She tolerated lidocaine during the procedure without difficulty. The patient awoke 6 hours later with lip and oral swelling. On presenting to the emergency department, she received epinephrine and intravenous steroids, and completed a course of prednisone. In the weeks thereafter, she continued to experience intermittent lip swelling, facial dermatitis, and urticaria. She consulted the allergy clinic. Pulmonary function testing revealed normal spirometry; skin prick testing and intradermal testing with lidocaine, mepivacaine, and proparacaine yielded negative results. Based on the temporal correlation between her dental work and symptom onset, the patient was referred for expanded patch testing. Immediate patch testing interpretation to detect urticaria was not performed. Testing results at 96 hours revealed no positive reactions to fragrance or flavoring chemicals. The patient had 1+ methyldibromoglutaronitrile, 1+ lidocaine, 1+ dodecyl gallate, and 1+ tin reactions (Fig 1). Lidocaine was relevant to her episode of oral swelling occurring hours after her dental procedure. The reactions to dodecyl gallate and methyldibromoglutaronitrile were not relevant. It is possible that the patient's persistent symptoms occurred due to allergy to tin. Her exposures included prior amalgam dental fillings (which typically contain mercury, silver, copper, and tin) and Crest Pro-Health toothpaste with the active ingredient stannous fluoride (Tin (II) fluoride). Upon discontinuation of this toothpaste, the patient's episodic lip swelling and urticaria resolved. She was symptom-free for 8 weeks, when an inadvertent reexposure to the same toothpaste was associated with recurrence of urticaria and lip swelling within a few hours. After subsequent avoidance of the suspected toothpaste, she again experienced remission of symptoms. We postulate that the stannous fluoride in the toothpaste may be the cause of her urticaria, although it is possible that another ingredient, such as a flavoring agent, is responsible. Metals are commonly associated with allergic contact dermatitis. However, tin has been associated with extremely low reaction rates.1Davis M.D. Wang M.Z. Yiannias J.A. Keeling J.H. Connolly S.M. Richardson D.M. Farmer S.A. Patch testing with a large series of metal allergens: findings from more than 1,000 patients in one decade at Mayo Clinic.Dermatitis. 2011; 22: 256-271PubMed Google Scholar Amalgam restorations have been implicated in localized as well as systemic hypersensitivity reactions.2Aggarwal V. Jain A. Kabi D. Oral lichenoid reaction associated with tin component of amalgam restorations: a case report.Am J Dermatopathol. 2010; 32: 46-48Crossref PubMed Scopus (14) Google Scholar, 3McGivern B. Pemberton M. Theaker E.D. Buchanan J.A. Thornhill M.H. Delayed and immediate hypersensitivity reactions associated with the use of amalgam.Br Dent J. 2000; 188: 73-76PubMed Google Scholar To our knowledge, no cases of allergy to stannous fluoride, an agent commonly found in toothpaste and oral rinse formulations, have been published.4Paraskevas S. van der Weijden G.A. A review of the effects of stannous fluoride on gingivitis.J Clin Periodontol. 2006; 33: 1-13Crossref PubMed Scopus (80) Google Scholar Additionally, small studies have suggested that contact allergies may play a role in chronic idiopathic urticaria in a small proportion of patients. Metals, particularly nickel, are the most commonly associated allergens.5Hession M.T. Scheinman P.L. The role of contact allergens in chronic idiopathic urticaria.Dermatitis. 2012; 23: 110-116Crossref PubMed Scopus (15) Google Scholar Based on our findings, in select patients we suggest that clinicians consider testing for additional allergens beyond standard patch testing series.