Therapeutic potential of plant-based therapies in pediculosis capitis: Systematic review and meta-analysis

Pediculosis capitis is a worldwide prevalent public health issue, mostly involving children. Resistance has been increasingly identified with conventional treatments such as permethrin or malathion. We aimed to evaluate the therapeutic potential of plant-based therapies for pediculosis capitis. PubMed, MEDLINE, Embase, EmCare, Web of Science, Cochrane, and ScienceDirect were searched for studies. Google Scholar was used to identify relevant gray literature from inception until 30th July 2023. Randomized controlled trials (RCTs) and non-randomized controlled trials (NRCTs) in English language evaluating a plant-based head lice treatment were considered for inclusion. This review was registered with the International Prospective Register of Systematic Reviews (CRD42023428674). Study characteristics, detection method, outcomes including final cure rate at 1-14 days following last treatment and adverse events were identified. Statistical analysis was performed with one sample t-test and linear mixed models. Random effects meta-analysis using forest-plots were used to describe intervention odds ratio. From 881 records, 20 studies were included comprising 13 RCTs and 7 NRCTs. All 20 studies were qualitatively analyzed and 9 RCTs were quantitatively analyzed. Based on RCT data, certain plant-based interventions may offer improved cure rates with overall higher mean final cure rate 0.86 (95% CI 0.73, 0.99) compared to conventional treatment 0.60 (95% CI 0.25, 0.95), however findings were limited by study heterogeneity (I2 = 83.2%) and methodological constraints. Local cutaneous irritation was the most frequent adverse event. Several limitations were identified, including confounding variables (e.g., inconsistent combing technique and variable plant-based interventions with multiple active ingredients and formulations), small sample sizes and lack of blinding. The risk of bias was high for NRCTs, while RCTs had some concerns. In conclusion, results should be interpreted cautiously in the context of study limitations. Further research is required to elucidate the efficacy and clinical role of plant-based therapies in PC.