The efficacy of Australian essential oils for the treatment of head lice infestation in children: A randomised controlled trial

Abstract

BackgroundThe increase in resistance of head lice to neurotoxic pediculicides and public concern over their safety has led to an increase in alternative treatments, many of which are poorly researched or even untested.MethodsA multicentre, randomised, assessor‐blind, parallel‐group trial (Trial 1) was conducted to compare the safety and efficacy of a head lice treatment containing Australian eucalyptus oil and Leptospermum petersonii (EO/LP solution; applied thrice with 7‐day intervals between applications) with a neurotoxic treatment containing pyrethrins and piperonyl butoxide (P/PB mousse; applied twice with a 7‐day interval) in children. A single‐blind, open trial (Trial 2) was conducted to assess the efficacy of EO/LP solution following a single application. In addition, skin irritancy and sensitisation tests using EO/LP solution were performed in adults and children. In vitro tests were performed to further assess the ovicidal and pediculicidal efficacy of EO/LP solution.ResultsEO/LP solution was found to be more than twice as effective in curing head lice infestation as P/PB mousse in per‐protocol participants (Trial 1; 83% vs 36%, P < 0.0001), and was also found to be 100% pediculicidal following a single application (Trial 2). Adverse events were limited to transient itching, burning or stinging. Further skin testing with the EO/LP solution reported no irritation or sensitisation in adults, or irritation in children. In vitro exposure of lice and eggs to the EO/LP solution resulted in 100% mortality.ConclusionThe efficacy, safety and relative ease of use of the EO/LP solution make it a viable alternative in treating head lice.

Essential Oils as a Potential Treatment Option for Pediculosis

“…In addition, other constituents in minor quantities may also have a possible synergistic or antagonistic activity [41,107]. Among the 22 genera of essential oils discussed above, which were reported to have pediculicidal activities, certain genera such as Aloysia, Cinnamomum, Eucalyptus, Eugenia, Lavandula, Melaleuca, Mentha, Myrcianthes, Origanum, Pimpinella, and Thymus have demonstrated high efficacy in killing the lice, which makes them strong candidates for clinical assays [23,[115][116][117]. Some major components of these plants belong to mono-oxygenated classes (1,8-cineole, linalool, pulegone, terpinen-4-ol, thymol), phenylpropanoids (anethole, cinnamaldehyde, eugenol), and monoterpene hydrocarbons (p-cymene, limonene) (▶ Table 1).…”

“…On the other hand, the concentrations of essential oils used in the ex vivo bioassays are quite low (generally below 5 %, mostly even below 1 %), whereas the essential oil-based prod-ucts for the treatment of lice infestations typically contain at least 10 % essential oil, which is around the threshold level of the concentration capable of causing vesicant reactions on human skin [110]. A clinical trial of a pediculicide containing more > 10 % of eucalyptus essential oils plus 1 % Leptospermum petersonii demonstrated satisfactory results [125]. In addition, some essential oils (e.g., M. pulegium, S. officinalis) and their compounds (e.g., pulegone, carvacrol, thujone, camphor, and menthol belonging to the chemical families of ketones and phenols) can be mildly to severely toxic to mammals.…”

“…In addition, some essential oils (e.g., M. pulegium, S. officinalis) and their compounds (e.g., pulegone, carvacrol, thujone, camphor, and menthol belonging to the chemical families of ketones and phenols) can be mildly to severely toxic to mammals. They often exert irritant, allergic, analgesic, or hepatotoxic, abortifacient, and hormone-like effects [123][124][125][126][127][128][129].…”

“…They are biodegradable, with low environmental toxicity and minimal environmental residual activity due to being highly volatile, and are well accepted by people who want to discontinue the use of synthetic chemicals [22]. They have previously been reported to be highly effective in the treatment of pediculosis [23]. The potency of essential oils against lice varies considerably across species.…”

Efficacy and repellency of some essential oils and their blends against larval and adult house flies, Musca domestica L. (Diptera: Muscidae)

“…The literature on insecticidal properties of botanicals, mainly EOs, is vast and expanding rapidly. Early research on these botanicals focused on pests of crop systems, but recently there has been strong interest in their application against pests of medical and veterinary importance, including mosquitoes (Khater and Shalaby , Govindarajan et al a,b, Muturi et al ), ticks (Abbas et al , Benelli and Pavela ), sucking lice (Khater et al , Greive and Barnes , Soonwera et al ), biting lice (Khater et al ), bed bugs (Sharififard et al , Gaire et al ), horn flies (Mullens et al , Zhu et al ), stable flies (reviewed in Showler ), primary screwworms (Chaaban et al , Tavares et al ), botflies (Khater et al , Khater ) and other myiasis‐causing flies (Khater and Khater ; Khater et al , Chaaban et al ). Prior to World War II, mosquito repellents were primarily plant‐based, with oil of citronella being the most widely used product and the standard against which others products were compared (Moore et al ).…”