Inclusion Criteria:  Males or females, 18 years of age or older inclusive;  History of recurrent HL lesions where:  Recurrence is defined as at least 4 episodes in the preceding 12 months; At least half of the episodes should be vesicular in nature; At least half of the episodes should be preceded by prodromal symptoms; Herpes labialis lesions are characterized by their localization on the cutaneous and/or mucosal surfaces of the lips; Willing to avoid, during the treatment phase, the use of anti-inflammatory, anti-herpetic, antibiotic and antiviral agents as well as steroids or other natural products that would interfere with the immune system response; Female participants of childbearing potential must be using a medically acceptable form of birth control for at least 1 month prior to screening (3 months on oral contraceptives) [e.g., hormonal contraceptives (oral, patch, injectable or vaginal ring), implantable device (implantable rod or intrauterine device), or a double barrier], abstinence or in same sex relationship and have a negative pregnancy test at Screening and prior to study drug administration. Female participants of non-childbearing potential must be amenorrheic for at least two years or have undergone surgical sterilization (i.e. tubal ligation/occlusion, hysterectomy and/or bilateral oophorectomy); Agreement to abstain from any mechanical disruption of the prodromal area or lesion (i.e. scrubbing, lancing, shaving the area, rubbing with alcohol, application of heat emitting devices used for cold sore treatment, etc.); Capable of giving signed informed consent as described in Section 10.1.4 which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol; Ability to understand and follow study-related instructions; Be willing and able to participate in all scheduled visits, treatment plan, and trial procedures according to the clinical protocol.  Exclusion Criteria:  Participants who did not develop herpes prodromal symptoms within 6 months after randomization in the study; More than 50% of recurrences that aborted spontaneously (without intervention) in the past 12 months; Primary herpes lesion outside the lips (e.g., nose, chin, etc.); Abnormal peri-oral skin condition that might affect the normal course of cold sores (e.g., eczema, psoriasis, etc.); Oral diseases whose prodromal symptoms may mimic those of herpes labialis, including recurrent oral aphthous disease; Allergy to any acyclovir or its containing agents; Milk allergy or known history of hypersensitivity to one of the components of Sitavig; Self-reported immunocompromised condition, including self-reported Human Immunodeficiency Virus (HIV) positive and previous bone marrow or organ transplant; Known medical history of renal disease; Females who are planning to become pregnant, are pregnant or lactating.