Causality assessment is the process of evaluating the relationship between a medical event, such as a disease or adverse drug reaction, and a specific exposure, such as a medication or environmental factor. The purpose of causality assessment is to determine whether the exposure is likely to have caused the event or whether the event is due to other causes. Causality assessment involves a systematic evaluation of the available evidence, including clinical data, laboratory results, medical history, and other relevant information. The assessment is typically based on a set of criteria, such as the temporal relationship between the exposure and the event, the strength of the association, the presence of alternative explanations, and other factors. Causality assessment is an important tool in pharmacovigilance, which is the science of monitoring and evaluating the safety of medicines. It is also used in epidemiological research to identify and understand the causes of diseases and other medical events. Causality assessment is not always straightforward, and there is often a degree of uncertainty involved in the process. However, it is an essential part of evaluating the safety and efficacy of medical treatments and is used by regulatory agencies, healthcare providers, and researchers to make informed decisions about patient care and public health.