Combined Neem Oil 6% w/w and Eucalyptus Oil 16% w/w Lotion for Treating Head Lice: In Vitro and In Vivo Efficacy Studies

ABSTRACTAimTo test a combined neem oil 6% w/w and eucalyptus oil 16% w/w lotion for the whole‐of‐life cycle treatment of human head lice (Pediculus humanus var. capitis) infestation.MethodPreliminary formulations of dilutions of neem and eucalyptus oils in isopropanol were tested for pediculicidal and ovicidal efficacies against Pediculus humanus var. capitis. This trial informed the development of a stable formulation consisting of neem oil 6% w/w and eucalyptus oil 16% w/w in a hydrophobic carrier (mixture of lanolin and silicones), which was also tested in vitro for pediculicidal and ovicidal efficacies against Pediculus humanus var. capitis. The lotion was then tested in vivo (clinical study) in volunteer Thai female students. At the conclusion of the in vivo study, participants and their parents/guardians completed a questionnaire pertaining to their perceptions and acceptance of the treatment.ResultsInitial in vitro testing demonstrated pediculicidal and ovicidal efficacies of 96% and 100%, respectively. The clinical study involving 45 volunteer Thai female students aged 7 to 12 years, with 2 applications of the lotion on the scalp and hair 1 week apart, showed significant in vivo activity. Pediculicidal efficacies of 93% and 97% and ovicidal efficacies of 80% and 100% were measured 2 days after the first and second application of the lotion. Participants and their parents/guardians indicated strong acceptance of the formulation.ConclusionThe combined neem oil 6% w/w and eucalyptus oil 16% w/w lotion demonstrated high pediculicidal and ovicidal efficacy for Pediculus humanus var. capitis infestation.