What is an FDA Form 483, and how is it different from a warning letter?

An FDA Form 483 is the list of observations an investigator gives management at the end of an inspection when they saw conditions that may violate the law. A warning letter is more serious: the FDA sends one when it identifies significant violations of federal requirements.

A 483 is not a final agency determination: the FDA weighs it together with the inspection report, the evidence collected and the company's response before deciding on further action. The FDA recommends answering a 483 in writing with a corrective action plan within 15 working days of the inspection's close. A warning letter lists the problems, requests a response within a set timeframe and lets the company explain if it disagrees. The FDA posts warning letters on its website. Once the FDA verifies that corrections were actually made, usually through a follow-up inspection, it may issue a close-out letter; it does not issue one based on promises alone.