E-fuse structures in back end of the line (BEOL) interconnects and methods of manufacture are provided. The method includes forming an interconnect via in a substrate in alignment with a first underlying metal wire and forming an e-fuse via in the substrate, exposing a second underlying metal wire. The method further includes forming a defect with the second underlying metal wire and filling the interconnect via with metal and in contact with the first underlying metal wire thereby forming an interconnect structure. The method further includes filling the e-fuse via with the metal and in contact with the defect and the second underlying metal wire thereby forming an e-fuse structure.