A dab of toothpaste has long been a favorite home remedy for clearing up pimples. But could it also cause them?

Despite suspicions from some zit-stricken folks seeking answers on online advice forums, dermatologists say there’s no reason to blame toothpaste for acne breakouts.

What toothpaste can cause, however, is irritation or allergic reactions in people with certain sensitivities, resulting in rashy bumps around the mouth or, perhaps, rosacea, a chronic condition of redness and skin sores that might be confused with traditional acne, said Dr. Richard Gallo, chair of the dermatology department at the University of California at San Diego.

People can be allergic to just about anything, but toothpaste’s mint and cinnamon flavorings, which can include the allergens balsam of Peru, cinnamic aldehyde and peppermint and spearmint flavors, are major culprits in skin reactions, Gallo said.

Trouble is, 95 percent of 153 toothpastes evaluated in a study did not list the specific flavoring ingredients, so people wouldn’t know to avoid them, researchers wrote in a study published in September in the Journal of Clinical and Aesthetic Dermatology.

People who are worried they are allergic to toothpaste ingredients should see a specialist who can test reactions to the specific ingredients, Gallo said.

But sometimes a skin flare-up has nothing to do with an allergy and is instead irritation.

Sodium lauryl sulfate, a detergent responsible for the foaming properties of toothpaste, is a common irritant that can aggravate the skin around the mouth just as might happen when you eat citrus or spicy foods, said Dr. Andrew Scheman, a dermatologist at the North Shore Center for Medical Aesthetics in Northbrook, Ill., who specializes in contact allergies and was the lead author on the toothpaste study.

— Chicago Tribune