Any oral or written communication from an end user of a medicinal product indicating that it had an adverse effect on a patient, did not function as specified, or appeared to be contaminated or defective in any way. The sponsor must promptly investigate all such complaints and document the investigation in a retrievable file. If the complaint is confirmed, corrective and preventive actions are required. Examples include FDA notification, product lot(s) withdrawal, product recall, and review of medical files of adverse events caused by the product. These requirements are found in US regulations in 21CFR 314, the CGP regulations.