Toothpaste does NOT help acne.  

Using toothpaste on a pimple has not been scientifically proven effective.

More Info: Most toothpaste consists of similar active ingredients including fluoride, an abrasive such as baking soda, and a foaming agent and antimicrobial such as sodium lauryl sulphate, none of which are proven to treat acne.  It is likely that those who tout toothpaste as an acne fighter have used a paste that contains methol or alcohol that dry the skin, which may have helped to shrink the acne lesion. 

Toothpaste May CAUSE Acne

If you are one of the 50 million Americans that suffer from allergies, putting toothpaste on your face could actually cause an allergic reaction that resembles acne. ["Allergy Facts and Figures." Asthma and Allergy Foundation]

As early as 1976 experts began to recognize that toothpaste may be the cause of an allergic reaction that is often mistaken for acne.  In a letter to the editor published in the journal Archives of Dermatology, a dermatologist shared his impromptu research on the subject.  Noting that many of his patients presented with acne only around the mouth and chin, often in the same fan-like pattern, he requested that they stop using toothpaste and instead switch to baking soda.  He reported that the results were overwhelming.  Nearly all acne cases showed marked improvement with almost complete clearing of acne. The patients that returned to using toothpaste, concerned about dental health, experienced an immediate return of acne. ." [Saunders,793]

Flavorings the Cause of Toothpaste Allergies

Getting rid of your acne-like toothpaste allergy may be as simple as switching flavors.  The additives most commonly associated with a toothpaste allergy are cinnamal, peppermint, caryone, anethole, and spearmint.  Unfortunately, as breath freshening agents, most toothpaste brands use at least one of these flavorings. The flavorings are used in higher concentrations in tartar control toothpastes to mask the unpleasant flavor of pyrophosphates, the active ingredient that helps delay calcification of bacteria plaque. [Tremblay, 445]