Niclosamide is primarily used as an anthelmintic drug to treat tapeworm infections. It works by inhibiting oxidative phosphorylation in the mitochondria of parasitic worms, leading to energy depletion and eventual death of the parasite. Due to its action in the gastrointestinal tract with minimal systemic absorption, it effectively targets intestinal helminths without causing significant toxicity to the host.

Beyond its antiparasitic use, niclosamide has shown potential in other therapeutic areas. It has been investigated for its antiviral properties, particularly against certain RNA viruses, due to its ability to modulate cellular signaling pathways. Research also explores its role in cancer treatment, as it can induce apoptosis and suppress multiple oncogenic signaling pathways such as Wnt/β-catenin, NF-κB, and mTOR.

Additionally, niclosamide has been studied for its antibacterial effects, especially against biofilm-forming bacteria, and for its potential in treating metabolic disorders by improving mitochondrial function and energy metabolism. Its broad biological activity makes it a candidate for drug repurposing in various diseases.