The present work reports the results of a multicentre study of toothpaste allergic contact cheilitis (TACC) conducted by GIRDCA (Gruppo Italiano Ricerca Dermatiti da Contatto e Ambientali). The study examined 54 patients with eczematous lesions on the lips, the possible cause of which was suspected to be the use of toothpastes. Patch tests were conducted with a standard series, a specially-targeted series (toothpaste cheilitis series, TCS), and with suspected toothpaste(s). A stop-restart test (SRT) was carried out with these, together with a use test to identify possible alternative products. The TCS produced 17 positive reactions in 13 patients, the most frequent being to spearmint oil. Of the 54 patients, 5 displayed positive reactions only to the TCS. The patch tests with toothpaste produced positive reactions in 11/32 patients, the SRT a positive response in 10/12 cases. The diagnosis of TACC was confirmed in 15/54 patients. Alternative products were identified for 5 patients. In conclusion, the allergens most frequently responsible for TACC were the flavourings, and the additional series proved to be useful in many cases (together with patch tests with toothpastes and the SRT) for correct diagnosis and to initiate effective prevention.