Low Temperature Hydrogen Peroxide Sterilisation: Everything You Need to Know

Understanding BS EN ISO 22441:2022 – The Standard Behind VHP Sterilisation 

BS EN ISO 22441:2022 sets the global framework for validating low temperature hydrogen peroxide sterilisation processes, ensuring both safety and repeatability for medical device manufacturers. In my previous blog post, I explored the importance of assessing residual hydrogen peroxide left on medical devices after sterilisation. It’s a critical part of ensuring patient safety. But it’s only one piece of the puzzle. This follow-up focuses on the validation of the sterilisation method itself, particularly when using VHP (Vapourised Hydrogen Peroxide) under the framework of BS EN ISO 22441:2022. 

A Brief History of Hydrogen Peroxide Sterilisation 

Hydrogen peroxide was first discovered in 1818 by Louis Jacques Thénard. Its strong oxidising properties made it useful as a disinfectant, and by the late 19th century, it was being used to treat a range of conditions, from scarlet fever to asthma. 

Its role in sterilisation, however, didn’t emerge until much later. In the late 1970s, hydrogen peroxide vapor was first identified as a potential sterilant. By the 1980s, gas plasma systems using hydrogen peroxide were being field-tested for medical device sterilisation. The real turning point came in 1993, when the first VHP steriliser was introduced to healthcare facilities as a safer alternative to ethylene oxide (EO). Since then, VHP has evolved from a novel concept to an FDA-recognised, established sterilisation method. From a basic disinfectant to a leading sterilisation method, hydrogen peroxide has transformed how we approach medical device sterilisation. 

Why Low Temperature Hydrogen Peroxide Sterilisation Matters

VHP sterilisation (short for vapourised hydrogen peroxide sterilisation) has become the go-to choice for heat-sensitive devices that can’t withstand traditional steam or EO sterilisation. VHP offers: 

• Low temperature processing (typically 37–44°C). 
• No toxic residues (breaks down into water and oxygen). 
• Broad material compatibility. 
• Shorter cycle times compared to EO. 
• Relatively easy installation in-situ.  

What ISO 22441:2022 Requires for VHP Sterilisation Validation

ISO 22441:2022 standard outlines how to ensure VHP sterilisation is safe, effective, and repeatable: 

• Process Development. Define cycle parameters (dosage, exposure time, venting, etc.) based on the medical device’s design and materials. 
• Sterilisation Validation. Demonstrate microbial efficacy and material compatibility. Medical devices must remain functional after sterilisation and meet sterility assurance levels. 
• Routine Monitoring. Use biological and chemical indicators to confirm each cycle meets validated conditions. 
• Documentation. Maintain detailed records of development, sterilisation validation, and routine control for traceability and compliance. 

What’s Outside the Scope of ISO 22441:2022 

While ISO 22441:2022 defines the framework for hydrogen peroxide sterilisation validation, it excludes other sterilisation chemistries and applications (focuses solely on VHP sterilisation). It does not cover: 

• Mixed chemical sterilisation methods. 
• Prion inactivation. 
• Environmental decontamination systems. 
• Occupational safety aspects of steriliser design. 

Why Validation Is Essential for Hydrogen Peroxide Sterilisation 

Sterilisation isn’t a one-size-fits-all process. Each medical device, whether it’s a simple surgical tool or a complex multi-material instrument, requires its own validation. That’s because geometry, material composition, and intended use all influence how effectively VHP can sterilise the device. 

Validation demonstrates that your low temperature hydrogen peroxide sterilisation process consistently achieves the required Sterility Assurance Level (SAL) – typically a 10⁻⁶ reduction in viable microorganisms.  

The Half-Cycle Approach to VHP Sterilisation Validation 

Just like with other sterilisation methods (e.g., steam or ethylene oxide), VHP validation often uses a half-cycle approach. This means we deliberately run the sterilisation process at half the intended dose or exposure time and then test whether it still achieves the desired SAL. 

Why half? Because if the process can sterilise under reduced conditions, it provides strong evidence that the full cycle is robust and reliable, even under slight variations. This conservative testing method ensures that the sterilisation process is both reliable and reproducible under real-world conditions.

Material Compatibility in Hydrogen Peroxide Sterilisation 

While VHP is praised for its low temperature and material compatibility, it’s not without challenges. Some polymers, adhesives, and coatings may degrade, discolour, or lose mechanical integrity after repeated exposure.  

That’s why material compatibility studies are essential. These aren’t just one-off tests, they need to simulate multiple sterilisation cycles, reflecting real-world use. The goal is to ensure that the device remains safe, functional, and compliant throughout its lifecycle. Material compatibility testing ensures that repeated exposure to hydrogen peroxide vapour doesn’t degrade device performance or safety. 

At Test Labs, we design these studies to assess: 

• Visual changes (e.g., cracking, warping, discolouration). 
• Mechanical performance (e.g., tensile strength, flexibility). 
• Functional integrity (e.g., sealing, articulation, electronics). 

Designing a Robust Hydrogen Peroxide Sterilisation Validation Plan 

In our lab, we’ve seen how VHP sterilisation can preserve delicate instruments while ensuring patient safety. But it’s not plug-and-play. Devices with long lumens, adhesives, or sensitive optics require tailored cycles and thorough validation. 

ISO 22441 helps us navigate this complexity. It gives structure to what was once a loosely defined process, ensuring that VHP sterilisation is as effective, as reliable and safe. 

A well-designed validation plan aligns with ISO 22441:2022 requirements while accounting for device-specific design, material, and use case. That means: 

• Identifying worst-case devices within a product family. 
• Selecting representative materials and geometries. 
• Running sub-optimal sterilisation efficacy test (half-cycle approach). 
• Assessing material compatibility impact of repeated cycles. 
• Documenting every step for regulatory compliance. 

And yes, it includes assessing residuals, as discussed in the previous post. Because sterilisation isn’t just about process efficacy. It is ensuring nothing harmful is left behind. 

Building Confidence in Low Temperature Hydrogen Peroxide Sterilisation 

VHP sterilisation has come a long way – from its early use as a disinfectant to its current role as a trusted sterilant for sensitive medical devices. But with that evolution comes responsibility. Validation is essential. And compatibility testing ensures that sterilisation doesn’t compromise safety or performance. 

At Test Labs, we’re committed to helping manufacturers navigate this process with confidence. Whether it’s validating a new device or refining an existing cycle, we’re here to make sure every product meets the highest standards.