Pharmacovigilance
Pharmacovigilance also known as drug safety, is the science of "collection, detection, assessment, monitoring, and prevention" of adverse effects of medicines.  Side effects are common with most medicines.  Mistakes such as overdose, and misuse and abuse of a drug as well as drug exposure during pregnancy and breastfeeding are also studied.   To sell or test a pharmaceutical product in most countries, information about these adverse events has to be collected and reported.