Out of Specification (OOS)

Out of Specification (OOS) refers to a test result that falls outside the predefined acceptable range for a particular quality parameter, such as strength, purity, or safety, in a product or sample. In pharmaceutical or manufacturing settings, OOS results indicate that a product does not meet established quality standards, which may require investigation and corrective actions to ensure safety, efficacy, and compliance with regulations. It’s a signal that something may be wrong in the process or product and needs review before approval or distribution.