Phase IV clinical trial synonyms refer to the post-approval study of a drug or medical device in the market. This phase is also known as the post-marketing surveillance phase, safety monitoring, or real-world evidence. The study monitors the safety, efficacy, and long-term effects of the drug on a larger patient population. Other synonyms for Phase IV clinical trial include observational study, drug surveillance, and post-approval research. The aim of this phase is to uncover any potential side effects, drug interactions, and unexpected benefits of the drug to improve patient safety. The FDA requires the pharmaceutical company to conduct phase IV clinical trials to ensure the product's safety and efficacy after being approved for sale.