Difference Between OOS and Deviation

OOS (Out of Specification) and deviation are terms commonly used in the context of quality management, particularly in pharmaceuticals industries. Here’s a brief overview of each term:

Out of Specification (OOS)

Definition: An OOS result occurs when the test results of a sample fall outside the established acceptance criteria or specifications.

Significance: OOS results are critical because they indicate that a product or process may not meet the required quality standards.

Response: When an OOS result is observed, it typically triggers a thorough investigation to determine the root cause of the deviation from specifications. The investigation aims to identify whether the result is due to laboratory error, instrument malfunction, or an issue with the manufacturing process. The process related OOS investigations should draw necessary Corrective Actions and Preventive actions (CAPA), to prevent the reoccurrence of the failure.


Definition: A deviation refers to any departure from approved procedures or specifications, whether intentional or unintentional, during the manufacturing, testing, or documentation process.

Significance: Deviations can occur at various stages, including production, testing, packaging, and distribution. They may affect the quality, safety, or efficacy of the final product.

Response: Deviations are usually subject to investigation to understand their cause and impact. Corrective and preventive actions (CAPA) may be implemented to address the root cause and prevent recurrence.

Deviations are classified as:

  • Minor: Does not have any impact on the product quality. e.g. spillage of raw material during dispensing.
  • Major: moderate to a considerable impact on product quality or GMP system e.g. breakdown of FBD during drying of granules.
  • Critical: significant impact on the production quality or GMP system. e.g.- Use of contaminated/ expired materials or solvents.

Both OOS and deviations are important in maintaining product quality and ensuring compliance with regulatory standards.

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Resource Person: Jairus Fernandes

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