Oral Ivermectin in Pediculosis Capitis: A Systematic Review and Meta-Analysis of Clinical Trials

Objective: Oral ivermectin has shown promise as a good option for treating pediculosis capitis (head lice). However, evidence regarding its efficacy and safety remains inconsistent in the literature. Therefore, this systematic review and meta-analysis was conducted to synthesize existing evidence and evaluate the efficacy and safety of oral ivermectin in treating pediculosis capitis. Methods: We systematically searched 3 major electronic databases—Medline via Ovid, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) for clinical comparative studies on oral ivermectin for head lice from inception to May 2025. To ensure a comprehensive search, we conducted supplementary searches in Google Scholar and Semantic Scholar, scanned ResearchGate, and manually examined the reference lists of identified studies. Data were extracted and assessed by 2 independent authors. The effect size for complete head lice clearance using oral ivermectin vs. topical therapies was calculated using a fixed effect model and expressed as risk ratios (RR) with a 95% confidence interval (CI). The results from randomized controlled trials (RCTs) are emphasized owing to higher quality evidence. This systematic review and meta-analysis was registered on the International Prospective Register of Systematic Reviews with ID CRD42024565100. Results: Seven studies were included, comprising 4 RCTs and 3 non-RCTs, with a combined total of 1,316 participants. Oral ivermectin (200–400 μg/kg, 2 doses 1 week apart) was given to 611 patients, while 705 participants received various topical therapies, including 0.5% malathion ( n = 454), 1.0% ivermectin ( n = 31), 1.0% permethrin ( n = 60), 5.0% permethrin ( n = 30), and d-phenothrin shampoo ( n = 130). The meta-analysis of RCTs indicated that oral ivermectin was superior to topical therapies in achieving complete lice clearance by day 15 (RR = 1.13, 95% CI: 1.08–1.18, P < 0.05), and similar efficacy of oral ivermectin was found from non-RCTs (RR = 1.39, 95% CI: 1.24–1.57, P < 0.05). Adverse events were slightly more common in the oral ivermectin group (RR = 0.88, 95% CI: 0.73–1.06, P > 0.05) with reported serious adverse effects of seizures. Conclusion: Oral ivermectin appears to be an effective and safe option for treating pediculosis capitis. However, further high-quality research is needed to better establish its long-term safety and comparative efficacy.