Comparative in vitro acaricidal activity of lemongrass preparations and selected formulations against Demodex folliculorum

Overgrowth of Demodex mites, microscopic parasites residing in human pilosebaceous units, contributes to skin disorders such as demodicosis and rosacea. Although topical ivermectin 1% is effective, its use is limited by cost and irritation; reported refractory or treatment-resistant cases have been reported, highlighting the need for natural alternatives. This study compared the in vitro acaricidal activity of lemongrass essential oil (LEO), lemongrass ethanolic extract (LEE), and selected LEO-LEE formulations containing ethanol 95% or PEG-40 with ivermectin 1% and control agents. Mites were collected from standardized skin surface biopsy residues of patients with demodicosis and rosacea and exposed to nine test agents: LEO, LEE, LEO + LEE + ethanol 95% (1:1:1), LEO + LEE + PEG-40 (1:1:0.5), ivermectin 1%, ethanol 95%, PEG-40, LEO + immersion oil (1:1), and immersion oil (control). Survival times of ten mites per agent were observed microscopically. All mites exposed to the test agents died within 44 min, whereas those in immersion oil survived for more than 240 min. The LEO + LEE formulations containing ethanol or PEG-40 exhibited the shortest mite survival times under the tested conditions, although 95% ethanol alone also showed substantial acaricidal activity. LEO-containing formulations demonstrated rapid in vitro demodicidal activity against D. folliculorum , with the ethanol- and PEG-40-containing LEO–LEE formulations showing the shortest mite survival times under the tested conditions. These findings support further investigation of lemongrass-based formulations as potential topical agents for Demodex -associated dermatoses. However, further studies are needed to clarify individual component contributions and evaluate safety, stability, and clinical efficacy.