Contact Reactions to Toothpaste and Other Oral Hygiene Products

Oral hygiene products such as toothpaste, dental floss, denture cleansers, and mouthwashes are essential for maintaining dental health. These products are used by people of all ages, and contact reactions can occur across the entire population. Toothpaste is composed of various ingredients including flavorings, preservatives, solvents, surfactants, colouring agents, abrasives, thickening agents, detergents, buffers, humectants, antiseptics, antacids, and fluoride salts. Among these, flavorings are the primary culprits in allergic reactions to toothpaste, with considerable overlap between toothpaste and food allergies.

Toothpaste and other oral hygiene products can lead to conditions such as cheilitis (inflammation of the lips) and stomatitis (inflammation of the mouth). Specific adverse reactions to these products include allergic and irritant contact cheilitis, contact stomatitis, perioral dermatitis due to allergic or irritant contact dermatitis, contact leukoderma, contact urticaria, and teeth discolouration. Such reactions are relatively rare given how frequently these products are used.

Allergic reactions to ingredients in oral hygiene products are infrequent, likely due to the rinsing process following their use. Approximately 30 potential allergens have been identified in toothpaste, and these are commonly found across most brands. Women are more likely than men to present with allergic contact reactions to toothpaste, possibly because they are sensitized to other fragranced products. Toothpaste is the second most common cause of contact cheilitis after lipsticks, and the leading cause of this condition in men.

Clinical Presentations

Cheilitis, or inflammation of the lips, is a common manifestation of contact allergies triggered by oral hygiene products. It typically presents as eczematous cheilitis affecting both lips, and symptoms such as dryness, itching, pain, or blistering are frequently reported.

Stomatitis can also result from allergic reactions, although it is less common than cheilitis despite the direct contact of products with the interior of the mouth. This condition can be acute or chronic, most commonly affecting the gums, tongue, and inner cheeks, with symptoms including burning pain, redness, swelling, and peeling.

In more severe cases, allergic reactions can extend beyond the lips, leading to perioral eczema or contact leukoderma. The skin surrounding the mouth may become inflamed or discoloured. Whitening of the skin, known as perioral leukoderma, has been linked to the presence of cinnamic aldehyde in certain toothpaste formulations.

Contact urticaria is another possible reaction, presenting with immediate swelling of the lips after contact with an allergen such as cinnamic aldehyde found in mouthwash. Repeated exposure to low concentrations of the allergen may not only result in swelling but may also lead to eczematous cheilitis, highlighting the diverse ways allergic reactions can manifest even with varying degrees of allergen exposure.

Common Allergens

Flavorings tend to be the most common allergens found in toothpaste. Ingredients such as spearmint, peppermint, menthol, and carvone, which are derived from the mint plant, are frequently implicated in allergic reactions. Beyond flavorings, other substances such as cinnamal, anethole, and propolis have also been reported to cause sensitivities.

Dental floss, mouthwashes, and denture cleaners may also contain allergens that cause reactions in susceptible individuals. While allergic reactions to these products are less common than those caused by toothpaste, they warrant attention, particularly in cases where symptoms persist.

In addition to allergic reactions, irritant contact reactions to oral hygiene products can also occur. Sodium lauryl sulfate (SLS), a detergent commonly found in toothpaste, is known to cause irritant contact dermatitis, especially around the mouth. In some cases, SLS has been linked to an increased frequency of aphthous ulcers.

Another potential side effect of oral hygiene products is the discolouration of teeth, particularly from the use of mouthwashes containing chlorhexidine. Although this ingredient is effective in eliminating bacteria, prolonged use can lead to cosmetic concerns such as tooth discolouration and altered taste sensations.

Diagnosis and Treatment

To properly diagnose contact allergies associated with oral hygiene products, patch testing is typically the first step. However, standard patch test series may not include the specific allergens present in these products. Extended testing, including the patient's own products, is often necessary for accurate diagnosis. While patch testing has its limitations, such as potential false negatives, it remains a valuable tool in identifying the source of the allergy.

Once a diagnosis is confirmed, the most effective treatment is avoiding the identified allergen and discontinuing use of the offending product. With elimination of the allergen, symptoms generally resolve within a few weeks. In the interim, topical corticosteroids can help manage eczematous reactions and provide relief during recovery.