This was an open, single-center multi-site, non-comparative study to evaluate the safety and performance of CSP-Night under actual-use conditions in subjects with herpes labialis of the lips and/or perioral skin. A sufficient number of subjects were screened to ensure that 45 subjects experienced and treated a cold sore outbreak in the course of 14 weeks. Subjects were instructed to initiate therapy within approximately 1 hour of onset of their first sign or symptom. Treatment was continued until the lesion healed, or for a maximum of 10 days. All subjects were expected to return to the study center for clinical assessments within 24 hours and 48 hours after initiating treatment, and every other day thereafter, with a final visit at Day 10 or at the time of completion/discontinuation if before Day 10. Diaries were completed each day, beginning upon initiation of therapy and continuing until study completion/ discontinuation, and included information on study product applications and compliance.