UL54

This will be a randomized, efficacy assessor-blinded, parallel group, pilot study of up to 40 subjects with documented herpes labialis. Patients will be treated with the study drug, acyclovir-penciclovir cream, or the active comparator of Abreva.
Potential subjects will be assessed during a screening visit that must take place no greater than 2 weeks prior to the Day 1 (Baseline) visit. During the screening period, subjects that meet all other entry criteria will undergo Ultraviolet susceptibility testing to determine the subject's individual minimal erythema dose (MED). Ultraviolet susceptibility testing takes place over two days with exposure to Ultraviolet light on specified regions on the subject's back followed by an assessment of the exposed areas 24 hours later to identify the MED. Subjects who have a measurable MED will be allowed to enroll in the study. Each subject will be randomly assigned in a 1:1 ratio to receive either acyclovir-penciclovir cream or Comparator (Abreva).
Patients who express a cold sore will track the lesion with a diary card to rate their pain levels, and any unusual symptoms at Day 1, Day 3, Day 5, Day 7, and Day 10. Patients may also take photographs of the lesion throughout the study.