Patch tests with 1% ethylenediamine and 1% aminophylline were positive at 48 and 96 hours. These results were consistent with a delayed type IV reaction. In another patient, urticaria was caused by a preparation containing phosphatidylcholine, lipoic acid, vitamin B3, and N-acetylcysteine. No allergological tests were performed; however, according to the authors, phosphatidylcholine was responsible for the urticaria because it is a histamine liberator. 6,8 Mesotherapy is currently regarded as a safe procedure for the cosmetic treatment of localized fat deposits. However, allergic reactions, although apparently rare, should be kept in mind.