The purpose of this study is to determine if Merlin, a mixture of ethanol and glycolic acid, is safe and effective in the treatment of cold sores.

Subjects who meet the requirements to participate in the study will be put randomly, and equally, into one of two groups: 1) a group receiving Merlin to treat their cold sore; or 2)a group receiving a placebo of just ethanol to treat their cold sore. Neither the subject nor the site will know which treatment they will be getting. Once the subject has been assigned to a treatment group, they will be given a kit containing a bottle of the treatment and special swabs to apply the liquid. The subject will be told to take the kit home and wait until they think they are starting to get a cold sore.

Once a subject begins to feel something or see something that they think is the start of a cold sore, they are to immediately call the clinic. Once the clinic confirms that the subject is in fact starting to get a cold sore, the subject will be told to open the kit and begin treatment. From the start of treatment, there will be twelve (12) treatments, with either Merlin or placebo, applied six (6) hours apart, up to 3 per day, over the next 96 hours (4 days). Each treatment of Merlin or placebo is made up of three (3) applications given twenty (20) minutes apart, for a total of thirty-six (36) applications. FOr each application, the subject will use the special swab to put the Merlin or placebo solution on their cold sore.

Subjects will need to report daily to the clinic for a minimum of 3 consecutive days, until either the cold sore is completely healed or 14 days from the start of treatment, whichever comes first. At each clinic visit the cold sore will be observed to determine at what stage it is at or if it has healed. The subject will also be asked how they are feeling.

Subjects will also be told to record in a diary the time of each application of Merlin or placebo. They will also be asked to record how much pain, if any, related to the cold sore, that they are feeling.

Inclusion Criteria:

• Male or female subject 18-75 years of age
• Female subjects must be using a medically acceptable form of birth control during the study. Acceptable birth control measures include, but are not limited to: abstinence, oral contraceptive pills or patch, injectable contraception, barrier contraceptives (condom, diaphragm with spermicide), IUD, vaginal contraceptive ring, surgical (hysterectomy, tubal ligation), vasectomized partner, and natural post-menopausal inability to conceive. Menopause is defined for this protocol as starting one year after the time of the last menstrual period.
• Subject must have a history of recurrent herpes labialis and report at least 3 separate recurrences (i.e. multiple herpetic lesions in one outbreak count as only one episode) during the preceding 12 months.
• Subject must have a history of experiencing prodromal symptoms of cold sores (e.g. itching, tingling, or burning) during at least half of their previous cold sore episodes.
• Subject must have a history of at least half of their cold sore episodes producing classical lesions (i.e., episodes that progressed through macule, papule, vesicle, crust, and healed).
• Subject must provide voluntary written informed consent to participate in this study.
• Subject is able to appear for a clinic visit within 24 hours from the time of treating cold sore and is able to return to the clinic for the full 14 day duration of the study if necessary.

Exclusion Criteria:

• Subjects with evidence of active malignancy or immunodeficiency disease within the last 30 days. Subjects who have completed therapy and are considered unlikely to relapse or who have had surgery and do not have any evidence of disease, are eligible for the study.
• Subject requires chronic use of immunomodifying drugs (e.g. systemic steroids) or topical steroids on or near the face; use of inhaled steroids does not exclude a subject from the study. If a subject is unlikely to get through the Treatment Phase of the protocol without requiring the use of an immunomodifying drug for a chronic condition the subject should be excluded.
• Subject requires chronic use of anti-viral medication.
• In females of childbearing potential, a positive urine pregnancy test at time of screening.
• Nursing mothers.
• Subject has abnormal skin conditions (e.g. acne, eczema, rosacea, psoriasis, albinism, or chronic vesiculobullous disorders) that occur in the area ordinarily affected by cold sores or has significant facial hair in the area of the cold sore that might affect the normal course of the cold sore or might impair accurate evaluation of the cold sore lesion.
• Subject has had a vaccine for herpes simplex virus type 1 (typically oral herpes) or 2 (typically genital herpes).
• Subject is currently enrolled in another clinical trial involving the use of a drug and/or a device.
• Subject requires chronic use of analgesics or non-steroidal anti-inflammatory agents (NSAIDs) except for low doses of aspirin (less than 325 mg/day) used for cardiovascular purposes. If a subject is unlikely to get through the Treatment Phase of the protocol without requiring the use of analgesia for a chronic condition, e.g. back pain, recurrent daily headaches, the subject should be excluded.