The purpose of this study is to compare the safety and efficacy of a 0.5% ivermectin cream to a placebo in subjects infested with head lice when used in an "at home" environment.

Inclusion Criteria:

• Subject must have an active head lice infestation defined as: At least 1 live louse (adult and/or nymph) present on the scalp and/or hair, as determined by a trained evaluator (with the exception of the male head of household who may self-assess as being lice free).
• Subject is male or female.
• Subject weighs at least 15kg (33 lbs).
• Subject is in good general health based on medical history.
• Each subject must have an appropriately signed Informed Consent agreement. A caregiver must sign an Informed Consent agreement for children not old enough to do so. Children of a specified age will be administered a child's assent form.
• The caregiver of a subject must be willing to allow all household members to be screened for head lice. If other household members are found to have an active head lice infestation, according to the criteria a (above), they must be willing and able to participate in the study. No more than one working male per family may be excluded from evaluation if he is self-assessed as being lice free and cannot come in due to his work schedule. If this individual may have lice, he must come to the test facility; otherwise the entire household will be excluded from study participation.
• Subject and/or their caregiver must be physically able and willing to apply the test article.
• Subject agrees not to use any other form of lice treatments (commercial, community-anecdotal, or mechanical/manual) while they are participating in the study.
• Following application and rinsing of Study Treatment, subject agrees not to shampoo, wash, or rinse their hair or scalp until the 24-hour post-treatment evaluation has been completed.
• Subject agrees that they will not cut or chemically treat their hair while they are participating in the study.
• Subject agrees to follow all study instructions.
• Female subjects of childbearing potential (including a female caregiver even if she is not being treated) must be willing to have a urine pregnancy test.
• In the event of a subject judged to be incapable of self-treating, the household must have a caregiver willing to apply the treatment at home.

Exclusion Criteria:

• History of irritation or sensitivity to ivermectin or the cream components, pediculicides or hair care products.
• Presentation at the treatment site with visible skin/scalp condition(s) that are not attributable to head lice infestation, such as an erythema score that is >2, blisters, vesicles which, in the opinion of the investigative personnel or sponsor, will interfere with safety and/or efficacy evaluations.
• Presentation at the treatment site with eczema or atopic dermatitis on the skin/scalp.
• Treatment with a marketed pediculicide (Over the counter [OTC] or Prescription) in the last 7 days.
• Any condition or illness that, in the opinion of the investigator, may compromise the objective of the protocol.
• Is receiving any other treatment which, in the opinion of the investigator or study monitor, may interfere with the study results.
• Females (including caregivers who come in contact with the investigational product) who are pregnant, nursing or planning a pregnancy. (NOTE: female caregivers and all enrolled females of childbearing potential must have a negative urine pregnancy test prior to treatment). If a household has a pregnant female who has an active case of lice, the entire household is excluded from participation. If this pregnant household member does not have an active infestation, this individual must NOT be the caregiver (one who provides treatment to other household members).
• Is of child-bearing potential and unwilling to use an adequate method of contraception for the duration of the study. Adequate methods of contraception include: abstinence, vasectomized partner, oral birth control pills, birth control injections or patches, Intra Uterine Devices, condoms with a spermicidal jelly or a diaphragm with spermicidal jelly, surgical sterilization.
• Participation in a previous investigational drug study within the past 30 days.
• Does not understand the requirements for study participation and/or may likely exhibit poor compliance, in the opinion of the investigator.
• Does not have a known household affiliation with their household members (i.e., do not stay in one household consistently, sleeping at one place several nights and then at another place or location). Household is defined as living in a shared area or space (for example the same house or apartment unit).