From the nickel in the button on your jeans to the herbal products in your expensive moisturizer, virtually any product that you use has the potential to cause an allergic reaction.
But toothpaste ingredients should be low on your list of potential allergens.
Of course, there have been some reports of allergic reactions that have been linked to toothpaste ingredients, but these reports are rare. The low degree of sensitization in most toothpaste ingredients contributes to the rarity of toothpaste allergies. The ingredients in toothpaste have changed over time and continue to change as companies refine their formulas to make them safer and more effective.
That said, flavourings often used in toothpaste, such as oil of peppermint, can cause an allergic reaction, but such reactions are usually mild and will resolve if you switch to a different flavour or brand of toothpaste. For example, a 1998 report from Denmark published in the journal Contact Dermatitis described a case of a person who developed severe chapped lips (cheilitis) as the result of a contact allergy to spearmint oil that was traced to toothpaste.
If you experience an allergic reaction, such as swelling, redness, dryness, or infection in your mouth, see your dentist immediately to rule out gum disease and to discuss your choice of toothpaste. You may find that you simply have sensitive teeth and gums, rather than a full-blown allergy, and that a mild flavoured toothpaste and soft-bristle brush may solve the problem.