Design: 152 patients were eligible to participate in the study and after a run-in period of two weeks consuming a placebo minidrink were randomized to one of the two experimental study groups: placebo minidrink (n=79) and a minidrink containing a combination of a pre- and probiotic (n=78). These minidrinks were consumed until the end of the study (day 140). At day 33 of the study the lip most prone to the development of a lesion was stimulated with UVB to provoke a lesion. During the entire study period subjects were checked for any clinical signs of a lesion, completed a self-assessment regarding the lesion and a QoL questionnaire at baseline (day 14), at day 49 and the end of the study (day 140). In addition, a blood sample was collected at baseline, at day 49 and at the end of the study to be analyzed for HSV-specific antibody concentrations , to check immune system specific functions.