Theranostics is an advanced field of medicine that involves a combination of targeted diagnostic tests with targeted therapy. It is also known as companion diagnostics, integrated medicine, Dx/Rx partnering, and pharmacodiagnostics. The theranostic utilizes nanoscience to unite diagnostic and therapeutic application in order to create a single agent, for diagnosis, drug delivery, and monitoring treatment response. Moreover, this technique utilizes specific biological pathways in the human body for obtaining diagnostic images and also deliver a therapeutic dose.