Clinical Endpoint Study of Ivermectin 0.5% Lotion

Inclusion Criteria: 1. Signed Institutional Review Board (IRB)-approved informed consent form that meets all criteria of current FDA regulations. For participants who are considered minors in the state the study is being conducted (\<18 years in most states), the parent or legal guardian should sign the consent form and the child will be required to sign a participant "assent" form, as appropriate. Participants 11-17 years of age will read and sign an IRB-approved assent form and participants 6-10 years of age will provide verbal assent. Participants 6 months-5 years of age will be exempt from providing assent based on the child's comprehension and cognitive skills. 2. The participant and/or the participant's parent (legal guardian) is willing to apply the study product as directed, comply with study instructions, and commit to all follow-up visits for the duration of the study. 3. Male or non-pregnant, non-lactating female, 6 months of age or older. 4. Females of childbearing potential must not be pregnant or lactating at Visit 1 (Day -1 to 1) (as confirmed by a negative urine pregnancy test with a sensitivity of less than 50 milli-international units/milliliter \[mIU/mL\] or equivalent units of human chorionic gonadotropin). Women of childbearing potential must agree to the use of a reliable method of contraception. (for example, total abstinence, intrauterine device, a double-barrier method, oral, transdermal, injected, or implanted non-hormonal or hormonal contraceptive) throughout the study. Female participants using hormonal contraceptives should have been on the same product/dosing regimen for at least 28 days before Visit 1 (Day -1 to 1) and should not change this regimen during the study. A sterile sexual partner is not considered an adequate form of birth control. 5. Index participants (that is, the youngest household member) must have an active head lice infestation, defined as ≥3 live lice (that is, live adults and/or nymphs), at Visit 1 (Day -1 to 1). 6. Household members participating in the study must have ≥1 live louse (that is; live adults and/or nymphs) at Visit 1 (Day -1 to 1). 7. All members of the household must be present for examination. Any male head of household who is unable to attend Visit 1 (Day -1 to 1) may be assessed by a second member of the household as being lice free. Exclusion Criteria: 1. Females who are pregnant, lactating or planning to become pregnant during the study period. 2. Participants who do not have a known household affiliation with their household members (that is, do not stay in 1 household consistently, sleeping at 1 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). 3. Any infested member of the household is unable or unwilling to be treated with the study product. This includes male heads of household who do not attend Visit 1 (Day -1 to 1) but report infestation with lice. 4. More than 3 members of the household infested with lice. 5. Presence of visible skin/scalp condition(s) or open wounds at the application site that are not attributable to head lice infestation and that in the opinion of the Investigator will interfere with safety and/or efficacy evaluations. 6. Presence of eczema or atopic dermatitis at the application site. 7. Use of any prescription, over-the-counter, or home remedies for the treatment of head lice within 7 days before Visit 1 (Day -1 to 1). 8. Use of pediculicides within 4 weeks before Visit 1 (Day -1 to 1). 9. Use of systemic anti-parasitic agents within four weeks before Visit 1. 10. Participants with very short (shaved) hair or who are planning to shave head during the study. 11. Use of any hair dye, bleaches, hair straightening, or permanent wave solution on the hair within 14 days before Visit 1 (Day -1 to 1). 12. History of allergy or sensitivity to pediculicides or hair care products. 13. History of any drug hypersensitivity or intolerance that, in the opinion of the Investigator, would compromise the safety of the participant or results of the study. 14. Significant history or current acute or chronic infectious disease, system disorder, Netherton's Syndrome, organ disorder (for example, hepatic or renal impairment) or insufficiency, immunosuppression (from medical treatment or disease), organ transplant, uncontrolled diabetes, uncontrolled hypertension, current ocular condition, or other medical condition that, in the Investigator's opinion, would place the study participant at undue risk by participating in the study. 15. Participants or non-infested household members who would act as the primary caregiver who are of intellectually competent age but unable to understand the protocol requirements, instructions, and study-related restrictions, the nature, scope, and possible consequences of the clinical study. 16. Receipt of any drug as part of a research study within 30 days before Visit 1 (Day -1 to 1). 17. The participant is a member of the investigational study staff or a member of the family of the investigational study staff. 18. Previous participation in this study.