Historical, Pharmacological, Clinical, and Regulatory Evolution of Hirudotherapy: An Evidence-Informed Traditional Narrative Review

Objectives: This traditional narrative review aimed to synthesize the historical development, pharmacological basis, contemporary clinical indications, safety concerns, contraindications, and regulatory framework of hirudotherapy.Methods: Literature was identified through targeted searches of PubMed, Scopus, CrossRef, Google Scholar, publisher databases, and official regulatory sources. The search focused on medicinal leech therapy, Hirudo medicinalis, hirudin, venous congestion, reconstructive surgery, microsurgery, knee osteoarthritis, contraindications, Aeromonas infection, and traditional and complementary medicine. Peer-reviewed reviews, systematic reviews, meta-analyses, randomized controlled trials, pharmacological studies, reconstructive surgery literature, historical sources, and official regulatory documents were prioritized.Results: Hirudotherapy has evolved from a traditional bloodletting practice into a mechanism-informed intervention with limited but clinically relevant modern indications. The strongest evidence-supported indication is the management of venous congestion after reconstructive microsurgery, replantation, and flap procedures. Symptomatic knee osteoarthritis appears promising but remains limited by methodological constraints and safety concerns. In contrast, broad claims involving cosmetic, metabolic, neurologic, reproductive, oncologic, or systemic diseases are insufficiently supported. Major risks include prolonged bleeding, anemia, allergic reactions, wound complications, and Aeromonas-related infection.Conclusion: Modern hirudotherapy should not be justified by historical continuity alone. It should be applied only within clearly defined indications, under medical supervision, with appropriate patient selection, infection-control measures, safety monitoring, and regulatory compliance.