8 things you need to know about medical device risk classification in the EU (MDR)

In the European Union (EU) medical devices are classified according to their risk and divided into classes I, IIa, IIb and III. And class I devices are divided into class I, Is, Im and Ir. What do these risk classes mean, and what risk are we talking about? 

Before you worry about the correct classification of your device, you should ensure that it is correctly qualified as a medical device. If you want to know whether your product is considered a medical device in the EU, you can find answers to your questions here:  “Is my product a medical device”?

The subsequent step is the medical device risk classification, based on the intended purpose and the inherent risk of a device (read more about the intended purpose here). The classification has wide-ranging consequences for the regulatory requirements the device has to comply with during the entire product lifecycle. The higher the risk potential of the device, the more proof with regards to safety and performance must be provided by the manufacturer before and after market access (read more about how the regulation of medical devices enhances patient safety here).


1. 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 (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 regulation. 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

There are 3 sub-classes under class I:.

Class Is: product that is delivered sterile

Class Im: product with a measuring function

Class Ir: products that are reprocessed

Once the correct risk class has been identified, manufacturers are still required to deal with residual safety and performance risks throughout their products’ lifecycle. These risks may originate from different root causes such as product variability, factors affecting the product’s use environment and different end-user interactions or unforeseen device failure and misuse. The MDR highlights the requirement to identify and evaluate use-related risks. Two regulatory aspects are essential in this context:

2. How do you classify a medical device with the classification rules?

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


The risk classification of medical devices is governed by rules laid out in Annex VIII to the MDR. The classification rules in Annex VIII of the MDR are divided into 4 subsections: non-invasive devices, invasive devices, active devices and special rules. The first Chapter of this Annex provides the relevant definitions required to apply the classification rules and the implementing rules. These outline the device characteristics and definitions that are specific for the classification rules, such as:

Duration of use: the difference between transient, short term, and long term;

Definition of what is considered an invasive device, what is regarded as an active device;

The first step consists of taking all implementing rules of Annex VIII to the MDR into account. Rule 3.5 states:

If several rules, or if, within the same rule, several sub-rules, apply to the same device based on the device’s intended purpose, the strictest rule and sub-rule resulting in the higher classification shall apply.

The second step is to check all classification rules of chapter III Annex VIII whether they are applicable to your medical device or not. If several rules or sub-rules apply, the strictest rule and sub-rule shall be applied. 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 — read more about intended purpose). It is essential to be as precise as possible, especially if the device could have a borderline medical purpose. 

3. How are accessories classified?

Per 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 to the device; all active implantable medical devices and their accessories fall under the highest risk category (Class III). Implementing rule 3.2 states: 

If the device in question is intended to be used in combination with another device, the classification rules shall apply separately to each of the devices. Accessories for a medical device shall be classified in their own right separately from the device with which they are used.

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

4. How is medical device software classified?

Under the former EU Directive 93/42/EEC concerning medical devices (MDD), as amended, software was a rather neglected topic. With the MDR, a new classification rule solely for software is introduced.  The MDR defines software as an ‘active device’, meaning that classification rules 9 to 13 of Annex VIII to the MDR have to be considered. In addition, special rules 15 and 22 can also apply to software.

Rules 9 to 12 are used to classify devices which are related to the exchange of energy and/or substances between the body and diagnostic or therapeutic active devices. However, the risks related to medical stand-alone software mainly relate to the consequences of indirect harm from failure to provide correct information. To reflect this risk, rule 11 was introduced in the MDR.

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 the document MDCG 2019-11 (Qualification and classification of software – Regulation (EU) 2017/745 and Regulation (EU) 2017/746).

This document focuses on main questions regarding qualification and classification and includes inter alia a table relating the MDR risk classification of software devices to the risk categorisation framework developed by the IMDRF (International Medical Device Regulators Forum). This framework categories the risk of software based on the combination of the significance of the information provided by the software to the healthcare decision (‘treat or diagnose’, ‘drive clinical management’ or ‘inform clinical management’) and the healthcare situation or patient condition (‘critical’, ‘serious’ or ‘non-serious’). 

The guidance has received criticism from industry and experts as it presents some issues. It was met with claims that it contains inconsistencies and errors, and some of its content is more likely to cause confusion than clarity on the interpretation of the regulation. The biggest criticism with the most significant consequences is the narrow interpretation of the MDCG of rule 11, which means there will hardly be any stand-alone software that falls into Class I. In other words, almost all medical device software, including apps, will be up-classified, multiplying the efforts and costs for the manufacturers to comply with the regulatory requirements. 

In this blog article you can read 10 facts you need to know about the MDR as a medical software manufacturer.

5. What changes concerning the classification have been introduced with the MDR? 

There are no essential changes in the classification approach described in article 51, but the MDR clarifies the process and role in unclear classification cases such as:

  • New classification rule for several products e.g., stand-alone software
  • Clarification on the duration of continuous use
  • Explanation when a device is considered to allow direct diagnosis

As the MDD did not sufficiently took account of the level of invasiveness and potential toxicity of certain devices which are introduced into the human body, the MDR added four new rules to obtain a suitable risk-based classification of devices that are composed of substances or of combinations of substances that are absorbed by or locally dispersed in the human body:

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

The new rules take into account if the device performs its action in or on the human body, where it is introduced or applied, and whether a systemic absorption of the substances of which the device is composed, or of the products of metabolism in the human body of those substances occurs.

6. What if you struggle with the classification?

The manufacturer is responsible for the correct classification of his devices. The MDCG issued two documents to help manufacturers which struggle with their MDR/IVDR classification:

  • MDCG 2019-11 Qualification and classification of software – Regulation (EU) 2017/745 and Regulation (EU) 2017/746
  • MDCG 2020-16 Guidance on Classification Rules for in vitro Diagnostic Medical Devices under Regulation (EU) 2017/746

So far, there is no MDCG guidance for classification rules for general medical devices which are not software devices. According to MDCG’s published plans for upcoming guidance documents (i.e. Ongoing guidance development and deliverables of MDCG Subgroups), you should expect the following ones in 2021:

  • Classification of medical devices
  • Borderline with medicinal products (including general guidance, definitions of pharmacological, immunological and metabolic means of action and diagnosis)

There are many reasons why the classification of a device may not be as easy or straightforward as expected, even when applying the classification rules the MDR provides. 

In case of a dispute between the manufacturer and his notified body, the competent authority (of the Member State in which the manufacturer has its registered place of business) 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 MDR, new scientific evidence, and/or any information which becomes available in the course of the vigilance and market surveillance activities as defined in Art. 51 MDR:

2. Any dispute between the manufacturer and the notified body concerned, arising from the application of Annex VIII, shall be referred for a decision to the competent authority of the Member State in which the manufacturer has its registered place of business. In cases where the manufacturer has no registered place of business in the Union and has not yet designated an authorised representative, the matter shall be referred to the competent authority of the Member State in which the authorised representative referred to in the last indent of point (b) of the second paragraph of Section 2.2 of Annex IX has its registered place of business. Where the notified body concerned is established in a Member State other than that of the manufacturer, the competent authority shall adopt its decision after consultation with the competent authority of the Member State that designated the notified body.

The competent authority of the Member State in which the manufacturer has its registered place of business shall notify the MDCG and the Commission of its decision. The decision shall be made available upon request.

3. At the request of a Member State the Commission shall after consulting the MDCG, decide, by means of implementing acts, on the following:

(a) application of Annex VIII to a given device, or category or group of devices, with a view to determining the classification of such devices;

(b) that a device, or category or group of devices, shall for reasons of public health based on new scientific evidence, or based on any information which becomes available in the course of the vigilance and market surveillance activities be reclassified, by way of derogation from Annex VIII.

4. The Commission may also, on its own initiative and after consulting the MDCG, decide, by means of implementing acts, on the issues referred to in points (a) and (b) of paragraph 3.

5. In order to ensure the uniform application of Annex VIII, and taking account of the relevant scientific opinions of the relevant scientific committees, the Commission may adopt implementing acts to the extent necessary to resolve issues of divergent interpretation and of practical application.


The manufacturer is responsible for the correct classification of his devices.

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

The MDR regulates medical devices, but it also applies to groups of products without an intended medical purpose. These groups are listed in Annex XVI. The classification rules were formulated/designed to classify medical devices and are not strictly transferable to products without an intended medical purpose. The example of active devices without medical purpose illustrates this problem: If the classification rules are applied to active devices covered by Annex XVI, they would all be classified in class I according to the residual criteria of rule 13 and rule 11. This may, in many cases, not capture the risk those devices pose to their users. 

The European Commission is aware of this issue and is preparing an implementing act to clarify the regulatory provisions applicable to Annex XVI products.

8. Where do you document the classification rationale?

Annex II of the MDR outlines the requirements applicable to a medical device’s technical documentation and specifies that the device description needs to include the device’s risk class and the justification for the classification rule applied following Annex VIII (per section 1.1(f)), as well as the rationale for qualification of a product as medical device (per section 1.1(e)).

You should base the qualification rationale on the definitions of medical device and accessory to medical device in MDR Article 2. However, a useful tool to present the qualification rationale for medical device software is the decision tree in MDCG 2019-11 guidance document.

Differences in medical device classification between EU & US

Are you wondering whether the risk classification under the MDR in the EU coincides with the risk classes in the USA?  Find more information on the differences in risk classes and how the risk class determines the regulatory pathway in the EU and US here.

How can Decomplix help?

Are there specific questions you would like to discuss? As you now know, the specifics and the intended use of a device are essential for the correct classification. We are happy to support you (re-)defining your intended purpose or classify your medical device. You can learn more about our services here.

More articles