Effectiveness of mosquito repellents for human: A systematic review of human-based studies

Mosquito repellents are personal protection tools against mosquito-borne diseases, but their effectiveness varies across active ingredients, formulations, and mosquito species. This systematic review followed PRISMA 2020 guidance to summarize human studies published between 2015 and 2025 that evaluated mosquito repellents delivered as topical application, wearable devices, spatial products, or treated clothing. Searches in Scopus and PubMed identified 1287 records, of which 19 met eligibility criteria. Data on complete protection time (CPT), repellency rate, safety, formulation type, and target species were synthesized descriptively because of methodological heterogeneity. Synthetic repellents, particularly DEET-based products in lotions or ointments, consistently provided the longest CPT, often five to nine hours, with repellency frequently approaching or exceeding 80-100% and no reports of adverse skin reactions. Natural repellents based on essential oils such as citronella, lemon eucalyptus, neem, and lemongrass usually achieve shorter CPT, commonly two to four hours. However, technologies such as microencapsulation and nanoemulsions improved performance in some formulations. Wearable products such as insecticide-treated clothing and spatial repellents demonstrated value as complementary measures in high-transmission settings. Synthetic topical repellents remain the most reliable option for prolonged protection, while optimized plant-based products may serve as safer alternatives for short-term or adjunctive use.