The use of Carbon Nanotubes has been done extensively over the last few decades. Due to their exemplary electromechanical characteristics, they have been significantly used to develop flexible sensors. Although they have been used in certain sectors, like wearable sensing applications, where their biocompatible nature has been tested, the toxicity of Carbon Nanotubes has also been a question. This chapter highlights the work done to analyze and determine the toxic nature of Carbon Nanotubes when considered in various physiochemical forms. It showcases the parameters that are attributed to their toxicology and the subsequent effect it has on their behaviour.