Niclosamide is primarily used as an anthelmintic drug to treat tapeworm infections. It works by disrupting the parasite’s energy metabolism, leading to paralysis and detachment from the host’s intestinal wall. Beyond its antiparasitic use, niclosamide has shown potential in research for treating various conditions including certain cancers, due to its ability to modulate signaling pathways like Wnt/β-catenin and NF-κB. It is also being investigated for antiviral activity, particularly against some RNA viruses, and for its role in metabolic disorders by affecting mitochondrial function. Its broad biological activity makes it a candidate for drug repurposing in oncology, virology, and metabolic disease research.