This is a Phase 2 single center study designed to compare the safety, local tolerability, and efficacy of 3 strengths of ivermectin treatment conditioner to placebo.

Inclusion Criteria:

• Subjects who are at least 6 months old and weighing at least 15 kg.
• Infestation with head lice and viable nits.
• Are otherwise in a normal state of health.
• Willing and able to attend all study visits as scheduled.
• Agree not to cut or chemically treat their hair in the period between treatment and the final visit.
• The subject and/or his/her parent/legal guardian have provided written informed consent, and, if appropriate, the child has provided assent.
• Females of childbearing potential must have a negative urine pregnancy test at screening and agree to take reasonable precautions against becoming pregnant during the study period.

Exclusion Criteria:

• Subjects who have received any over the counter or prescription treatment for head lice in the last 2 weeks.
• Subjects unable to comply with the study obligations and all study visits.
• Subjects with eczema or other chronic conditions of the scalp and skin.
• Subjects in a household with more than 5 infested members.
• Subjects with a history of allergy to ivermectin or any ingredients commonly included in hair products such as shampoos, hair conditioners, or styling aids.
• Subjects with neurologic conditions including a seizure disorder or history of seizures.
• Subjects with an infestation of body lice or pubic lice (determined by questioning).
• Subjects suffering from a condition likely to require medical attention, including administration of oral or systemic antibiotics, oral or systemic corticosteroids, or any other treatment, which in the opinion of the Investigator and visiting physician could influence the results of the study.
• Subjects with other diagnoses which, in the opinion of the Investigator, would interfere with efficacy or safety assessments or would preclude study participation.
• Subjects with very short (shaved) hair.
• Subjects who have been treated with a systemic antibiotic within the previous 2 weeks before screening.
• Subjects who have been previously enrolled in any clinical study within the past 30 days; subjects may not participate in another study while participating in this study.
• Pregnant and/or nursing females.

Adverse event data were collected from Day 1 up to Day 28 post-application.