8 things you need to know about medical device risk classification under the EU MDR

Medical device risk classification is based on the intended purpose and the inherent risk of a device. The classification has wide-ranging consequences for the regulatory requirements over the product’s entire lifecycle. The higher the risk of a device, the more proof of safety and performance must be provided before and after market access. In the European Union, medical devices are classified according to their risk as class I, IIa, IIb and III. If you are uncertain about what these risk classes mean, read on. Before classifying your device, you should ensure that it qualifies as a medical device.

Replaces the version of 28.01.2022

Key takeaways:

  • Medical device manufacturers should not assume that their existing classification under the former Directive 93/42/EEC (MDD) applies as is under the EU MDR. They should always verify the classification from scratch, per Annex VIII of the EU MDR.
  • Accessories for medical devices and “Annex XVI products” must be classified in their own right. For “Annex XVI products”, additional rules apply.
  • All definitions, implementing rules and classification rules in EU MDR Annex VIII must be considered for the determination of the correct device class. Guidance documents MDCG 2021-24 as well as MDCG 2019-11 for medical device software are essential resources to consider.


What is a risk class of a medical device?

The inherent risk of a device is a crucial element to be considered in the practical implementation of the new European Regulation (EU) No. 2017/745 on medical devices (EU MDR) in order to set a reasonable and proportionate level of evidence to achieve compliance. 

In this context, the term “risk” means two things: the risk class of a device and the potential and actual risk a manufacturer has to manage. These things are not fundamentally different but are dealt with in distinct parts of the EU MDR. In this blog post, the focus is on the classification of devices based on risk that introduces the division of devices into four product classes for conformity assessment procedures. 

The risk classes are:

  • Class I – low risk
  • Class IIa – medium risk
  • Class IIb – medium risk
  • Class III – high risk

Class I is complemented with three sub-classes addressing specific features:

  • Class Is – devices that are delivered sterile
  • Class Im – devices with a measuring function
  • Class Ir – devices that are reprocessed

Once the risk class of a device is identified, manufacturers are required to deal with the residual safety and performance risks throughout their products’ lifecycle. These specific risks may have different origins, such as the nature of the device’s invasiveness, the deployment of energy or substance, the product’s use environment and different end-user interactions, materials and manufacturing variability, or unforeseen device failure and misuse. The EU MDR highlights the requirement to identify and evaluate use-related risks. Two strongly interacting regulatory aspects are essential in this context: Risk Management and Post-market Surveillance.

How do I classify a medical device?

To classify the medical device, you need to consult Annex VIII of the EU MDR, consisting of three chapters: 


The classification rules in Annex VIII of the EU MDR are divided into 4 subsections: non-invasive devices, invasive devices, active devices, and “special” rules. Special rules may apply to devices that already fall under any of the previous 3 categories, and therefore need to be always considered.

The first chapter of this Annex provides the relevant definitions required to apply the classification rules and the implementing rules. The definitions outline the device characteristics that are specific for the classification rules, such as:

  • Categories of duration of use: Transient, short term, and long term;
  • Definition of invasive versus non-invasive devices;
  • Definition of active versus non-active devices

The following steps should be followed: 

  1. Evaluate each definition of both EU MDR Article 2 and Annex VIII chapter I, for applicability to the device in question.
  2. Take all implementing rules in Annex VIII of the EU MDR into account. Implementing rules provide general guidance to the classification process. For example, if several rules or sub-rules apply, the strictest rule and sub-rule shall be applied.
  3. Check all classification rules of chapter III Annex VIII, whether they are applicable to your medical device or not. As the intended purpose is the basis for applying the classification rules, it might be helpful to explicitly mention any limitations  (i.e. what the medical device is not intended to be used for). It is essential to be as precise as possible, a small difference of the wording can make a big difference from a regulatory viewpoint.

The extensive and useful guidance document MDCG 2021-24 discusses details on how to interpret and apply Annex VIII and also brings examples. It should always be used alongside Annex VIII when classifying a device.

How are accessories classified?

Per EU MDR Article 2(2) a medical device accessory is:

“an article which, whilst not being itself a medical device, is intended by its manufacturer to be used together with one or several particular medical device(s) to specifically enable the medical device(s) to be used in accordance with its/their intended purpose(s) or to specifically and directly assist the medical functionality of the medical device(s) in terms of its/their intended purpose(s).” 

Before classifying your device, it is important that you determine whether a given item that you consider an “accessory” to your main device falls under this legal definition. 

Accessories to medical devices are classified separately from the device (or “in their own right”, as implementing rule 3.2 states).

A man gesticulates. He is sitting in an office chair. Large windows in the background.

In the European Union medical devices are classified according to their risk and divided into classes I, IIa, IIb and III.

How is medical device software classified?

The EU MDR defines software as an “active device”, meaning that classification Rules 9 to 13 in Annex VIII that apply to active devices have to be considered. Among these, Rule 11 is specific to software. In addition, special Rules 15 and 22 can also apply to software.

Rules 9 to 12 are used to classify devices which are involved in the exchange of energy and/or substances between the body and active devices for diagnostic or therapeutic purposes. However, the risks related to medical “standalone” software mainly stem from incorrect or missing information, which can be indirectly harmful. To reflect this risk, Rule 11 was introduced. 

Classification Rule 11 states:

 “Software intended to provide information which is used to take decisions with diagnosis or therapeutic purposes is classified as class IIa, except if such decisions have an impact that may cause:

  • death or an irreversible deterioration of a person’s state of health, in which case it is in class III; or
  •  a serious deterioration of a person’s state of health or a surgical intervention, in which case it is classified as class IIb.

Software intended to monitor physiological processes is classified as class IIa, except if it is intended for monitoring of vital physiological parameters, where the nature of variations of those parameters is such that it could result in immediate danger to the patient, in which case it is classified as class IIb. 

All other software is classified as class I.”

Further clarification on the application of Rule 11 is given in guidance document MDCG 2019-11. This document focuses on the qualification and classification of medical device software and includes an informative table linking the EU MDR risk classification of software to the risk categorization framework developed by the IMDRF (International Medical Device Regulators Forum). The approach taken in the IMDRF publication (IMDRF/SaMD WG/N12FINAL:2014)  combines the significance of the information provided by the software to the healthcare decision (“treat or diagnose”, “drive clinical management” or “inform clinical management”) with the healthcare situation or patient condition (“critical”, “serious” or “non-serious”).

For more details, see our blog article on Medical device software (MDSW) under the EU MDR and IVDR.

My device was previously classified under the former MDD. What changes have been introduced with the EU MDR?

There are no essential differences in the classification approach described in Article 51, but the EU MDR clarifies various aspects, such as: 

  • New classification rules for several products e.g., medical device software, substance medical devices, nanomaterials.
  • Clarification on the duration of “continuous use”.
  • Explanation of when a device is considered to allow direct diagnosis.

As the former Directive 93/42/EEC on medical devices (MDD) did not take sufficient account of the degree of invasiveness and the potential toxicity of certain devices, in addition to Rule 11 for medical device software, the EU MDR added four new “special” rules:

  • Rule 19 – Devices incorporating or consisting of nanomaterial
  • Rule 20 – Invasive devices with respect to body orifices to administer medicinal products by inhalation
  • Rule 21 – Substances or of combinations of substances that are intended to be introduced into the human body via a body orifice or applied to the skin and that are absorbed
  • Rule 22 – Active therapeutic devices with an integrated or incorporated diagnostic function which significantly determines the patient management

In addition, the former special Rule 18 for blood bags in the MDD was discontinued under the EU MDR as a separate rule, and is now part of Rule 2.

Some fine-tuning has been brought to other classification rules that already existed under the MDD and, the rule numbering has been affected. As such, manufacturers should not assume that their former MDD classification applies as is and should always verify the classification from scratch under the EU MDR.

What if I struggle with the classification?

The manufacturer is responsible for the correct classification of his devices. As mentioned above, the MDCG issued two guidance documents to help manufacturers with EU MDR classification: 

  • MDCG 2021-24 Guidance on classification of medical devices.
  • MDCG 2019-11 Qualification and classification of software – Regulation (EU) 2017/745 and Regulation (EU) 2017/746.

If these guidance documents do not suffice, the manufacturer can send an inquiry to the concerned competent authority (of the Member State where the manufacturer has its registered place of business) or, in the case of devices that require the involvement of a Notified Body in their conformity assessment process, the manufacturer can discuss the selected classification with its Notified Body.

Various classic medical devices on a white background

The manufacturer is responsible for the correct classification of his medical device.

In case of a dispute between the manufacturer and its Notified Body, the competent authority will – after consulting the MDCG – decide on the classification and inform the MDCG and the commission about the decision. The competent authority will base its decision upon the classification rules given in Annex VIII of the EU MDR, new scientific evidence, and/or any information which becomes available in the course of the vigilance and market surveillance activities, as defined in Article 51 of the EU MDR.

Beware that there might be situations where the classification under the EU MDR  turns out to be convoluted, due to an incorrect qualification as medical device, which might be revealed through questions such as:

  • Does my product qualify as a medical device?
  • Is my device a medical device or an in-vitro diagnostic device?
  • Is my product a medical device or a medicinal product?
  • Delimitation to other regulated markets such as cosmetics, food or general consumer products.

The Medical Device Coordination Group (MDCG) has issued a Manual on borderline and classification (current version 3 – September 2023). There is also the more specific MDCG 2022-5 guidance on borderline between medical devices and medicinal products under the EU MDR. To learn more about the qualification of medical devices and borderline issues, read our blog article Is my product a medical device in Europe? How to determine if your product requires medical device CE marking

Do classification rules also apply to devices without a medical purpose?

The EU MDR regulates not only medical devices, but also specific groups of similar products without an intended medical purpose. These groups are listed in Annex XVI, and thus commonly referred to as “Annex XVI products”. 

In general, Annex XVI products are classified in accordance with the classification rules in Annex VIII of the EU MDR. Accessories to Annex XVI products also fall under the EU MDR and, per Annex VIII Chapter II 3.2, they shall be classified in their own right. 

There are however some exceptions, documented in Regulation (EU) 2022/2347 on the reclassification of Annex XVI products that are considered to be active devices. These include the following “active devices”:

  • High intensity electromagnetic radiation emitting equipment intended for the use on the human body for skin treatment is class IIb, unless it is intended for hair removal only in which case it is class IIa.
  • Equipment intended to be used to reduce, remove or destroy adipose tissue is class IIb.
  • Equipment intended for brain stimulation that apply electrical currents or magnetic or electromagnetic fields that penetrate the cranium to modify neuronal activity in the brain is class III.

Where do I document the classification rationale?

Annex II of the EU MDR on technical documentation specifies that the device description needs to include the device’s risk class and the justification for the classification rule applied (per section 1.1(f)).

It is good practice to present the justification in the form of a table, where all 22 classification rules in Annex VIII of the EU MDR are listed, and the justification for applicability or non-applicability is indicated for each of them. This shows to the Notified Body or competent authority who might review the documentation, that the manufacturer understands the classification process and has thoroughly applied it. In our consultancy practice, we recommend to do so even when the non-applicability is obvious, for example the non-invasive and invasive rules would never apply to medical device software.

How Decomplix can help

As you now know, the specifics and the intended use of a device are essential for the correct classification under the EU MDR. Are there specific questions you would like to discuss?

Are you wondering whether the risk classification under the EU MDR coincides with the risk classes in the USA?  Find more information in our bespoke article on Medical device regulatory strategy – US vs. EU.

We are happy to support you (re-)defining your intended purpose or classifying your medical device under the EU MDR, and pointing out the relevant differences from a US classification. Learn more about our services.

Further reading

More articles