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    ISO 11135

    Standard for development, validation, and routine control of ethylene oxide (EO) sterilization.

    Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed May 5, 2026

    Definition

    ISO 11135 specifies requirements for EO sterilization processes for medical devices, including microbiological qualification, dose setting, process challenge devices, and parametric release options.
    What the regulation says
    ISO 11135:2014 specifies the requirements for the development, validation, and routine control of an ethylene oxide sterilization process for medical devices. The standard outlines the requirements for equipment, process control, and validation to ensure the sterility assurance level (SAL) for terminally sterilized medical devices in accordance with national and international regulations, such as those overseen by the FDA and the EU MDR. It does not specify requirements for developing, validating, and routinely controlling a process for inactivating the causative agents of spongiform encephalopathies or other unconventional agents.

    What this means in practice

    EO sterilization capacity has been a persistent supply-chain risk; ISO 11135 conformance is essential to qualify alternative sites.

    Examples

    • A manufacturer validates an ethylene oxide sterilization cycle for a new surgical implantable device, ensuring all parameters meet ISO 11135 requirements, such as gas concentration, exposure time, temperature, and humidity.
    • During a regulatory audit, a medical device company demonstrates compliance with ISO 11135 by presenting documentation for routine biological indicator testing and equipment calibration records for their ethylene oxide sterilizer.
    • A contract sterilizer develops a process challenge device (PCD) that accurately represents the most difficult-to-sterilize product within a load, as mandated by ISO 11135, for ongoing sterilization monitoring.
    Common pitfalls
    • •A common pitfall is the failure to re-validate the sterilization process after changes to the product, packaging, or equipment, which can compromise sterility assurance.
    • •Another mistake is neglecting to perform routine biological indicator testing or chemical indicator monitoring, leading to undetected sterilization failures.
    • •Assuming that a generic sterilization cycle is appropriate for all devices, without specific validation for each product, can result in inadequate sterilization.
    • •Improper storage and handling of ethylene oxide gas cylinders or sterilized products can compromise sterility and safety.
    • •Not adequately training personnel involved in the sterilization process can lead to procedural errors and non-compliance with the standard.

    Frequently asked questions

    The primary purpose of ISO 11135 is to provide requirements for the development, validation, and routine control of an ethylene oxide sterilization process for medical devices, ensuring product safety and efficacy.
    Grouped by theme

    Primary references

    3 sources
    Link health: 3 verified· last checked 2026-06-20
    ISO·2FDA·1
    1. 1
      ISO 11135
      Verified
      ISOiso.org
    2. 2
      FDA Recognized Consensus Standards
      Verified
      FDAaccessdata.fda.gov
    3. 3
      ISO Standards Catalogue - Health
      Verified
      ISOiso.org

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