Despite the importance of knowing a drug’s mechanism of action (MOA) for its success in clinical trials and for understanding its potential side effects, it is not a requirement for Food Drug Administration (FDA) approval. As a result, many drugs on the market are administered without knowing their precise mechanism of action. The current challenge is to predict whether a drug presents a warning toxicity and how it interacts with its environment and therefore better characterize its mechanisms via multi-layer omic network analysis approaches.