Medical device classification: what is it and why is it used?

What is classification under the MDR?

Classification assigns a medical device to class I, IIa, IIb or III under the rules of Regulation (EU) 2017/745. Article 51 requires the intended purpose and inherent risks to be taken into account. Annex VIII sets out the detailed rules. 1 

The class determines, among other things, how conformity must be demonstrated. For many devices, this requires a notified body. It also affects the frequency of certain reports and specific obligations relating to clinical data. 2 

Classification does not assess the quality of an individual unit. A class I device must still meet the applicable safety and performance requirements. Class III is a regulatory category; it does not mean that a properly assessed device is defective.

Qualification comes first: does the product fall under the MDR?

Before selecting a rule, establish which regulatory framework applies. Qualification determines whether the product is a medical device or another product covered by the MDR. Classification then determines its class. 1  2 

Start with the intended purpose. The manufacturer's statements in the labeling, instructions for use, promotional materials and clinical evaluation all matter. Establish the medical purpose, intended users, patient population and how the product is used. 1 

For example, a system used solely to schedule appointments calls for a different assessment from software that processes patient data to support treatment decisions. The word "medical" in a trade name does not define the function. MDCG 2019-11 rev.1, published in June 2025, provides guidance for software. 3 

In vitro diagnostic medical devices fall under the IVDR and have separate rules. That framework uses classes A, B, C and D. These must not be carried over into MDR classification. MDCG 2020-16 rev.5, published in September 2026, explains the IVDR rules. 8  4 

How should classes I, IIa, IIb and III be understood?

The class affects the scope of conformity assessment and the evidence required. It is assigned by applying the rules to the particular device. Describing a product as "simple" or "complex" is not enough to select a class. 1  2 

• Class I: for devices without specific characteristics requiring notified body involvement, the manufacturer performs conformity assessment without a notified body.
• Class IIa: requires a notified body in the appropriate conformity assessment procedure.
• Class IIb: also requires a notified body; the scope of assessment depends, among other things, on whether the device is implantable.
• Class III: follows the procedures provided for this class, with specific requirements for assessing documentation and clinical evidence. 1  2 

This is an outline of the routes for standard devices. Custom-made devices and investigational devices have their own rules, which cannot be inferred from the class alone.

What do Is, Im and Ir mean?

These designations describe class I devices:

• Is: devices placed on the market in sterile condition,
• Im: devices with a measuring function,
• Ir: reusable surgical instruments.

For these devices, Article 52(7) provides for notified body involvement limited to the relevant aspects: sterility, metrological requirements or reuse. For Ir, this includes cleaning, disinfection, sterilization and the related instructions. 1  5 

"Reusable" does not automatically mean Ir. The device must meet the definition of a reusable surgical instrument, and the classification rules must be applied correctly. 2 

Which characteristics determine the class?

Annex VIII contains 22 rules. Their application depends on the device's characteristics and intended purpose. The assessment considers duration of use, invasiveness, the site of contact with the body, whether the device is active and its specific functions. 1  2 

Duration of use and invasiveness

The MDR distinguishes transient, short-term and long-term use. In general, these mean continuous use for less than 60 minutes, between 60 minutes and 30 days, and more than 30 days, respectively. The detailed provisions for calculating continuous use must also be considered, including applicable cases of immediate replacement with the same type of device. 1  2 

It also matters whether the device penetrates the body, by which route and whether it remains in the body after a procedure. The definitions of invasive, surgically invasive and implantable devices have specific wording. A general description such as "patient contact" is not sufficient to apply them.

Function, energy and specific rules

For active devices, relevant factors include the type of energy delivered and the possible effects of its use. Separate rules cover, for example, contraception, disinfection of certain devices and products incorporating certain substances. 1  2 

Continue the assessment after finding the first applicable general rule. A specific rule may also apply and lead to a different result. Where several rules or sub-rules apply, use those that result in the highest class. 1 

How is medical device software classified?

Rule 11 provides for class IIa for software that supplies information used to make diagnostic or therapeutic decisions. If the impact of those decisions may cause serious deterioration in health or a surgical intervention, class IIb may apply. If it may cause death or irreversible deterioration in health, the rule specifies class III. 1  2 

The rule also covers monitoring physiological processes. It distinguishes monitoring vital physiological parameters where the nature of variations could result in immediate danger to the patient. All other software covered by the final sentence of Rule 11 is classified as class I. 1 

The assessment needs more detail than "the app advises a doctor." Describe the information it provides and its significance for the decision. Check the other rules too, including the provisions for software that drives a device or influences its use. 1  3 

What changes after sales begin?

For class I devices, the manufacturer prepares a post-market surveillance report under Article 85 MDR. For classes IIa, IIb and III, it prepares a periodic safety update report (PSUR) under Article 86. The PSUR must be updated at least every two years for class IIa and at least annually for classes IIb and III. 1  2 

Classification also affects certain clinical evaluation and traceability obligations. Requirements associated with implantation and other device characteristics must be checked separately. The class alone does not describe every applicable obligation.

For a device using transitional provisions, do not automatically apply the entire scheme above. Guidance for legacy devices distinguishes the classification used to determine the end of the transitional period from the classification relevant to certain ongoing obligations. 6 

Who is responsible for classification?

The manufacturer determines the class and includes the justification for the rules applied in the technical documentation. A notified body assesses this element when involved in the relevant procedure. The MDR provides for the competent authority to resolve a dispute between the manufacturer and notified body over the application of Annex VIII. 1 

The justification should allow the decision to be reconstructed. It is useful to record the device description and intended purpose, the characteristics relevant to classification and the assessment of applicable rules. A date and approval can be added under the company's document control procedures. The MDR does not prescribe a single form.

Classification rules and risk analysis

The class follows from applying the regulatory rules. Risk analysis identifies hazards associated with the particular device and assesses the controls. Both activities should use a consistent product description, but the outcome of a risk analysis does not allow the class specified by a rule to be lowered at will. 1  2 

Similarly, a European Medical Device Nomenclature (EMDN) code describes the type of device when registering it in EUDAMED. It does not replace risk classification under the MDR. 7 

What does this mean in practice?

Review classification before setting the budget and schedule for conformity assessment. The recommended sequence is:

Hypothetical example: extending a dressing's intended purpose

Which mistakes should a review avoid?

Copying a competitor's class provides no justification for your own device. The other product may have a different intended purpose, duration of use or operating principle. Carrying an MDD classification over without assessing the MDR creates a similar problem.

Check whether the rules were assessed for all claimed intended purposes and whether a change to the instructions for use was reflected in the classification document. Resolve uncertainties before selecting a procedure, because the outcome determines the work plan and notified body involvement.

How can Neximed support the team?

Classification requires a manufacturer decision based on the MDR and an appropriate device description. When organizing work following a change in classification, the Training module can help maintain training records and evaluate training effectiveness. If a review identifies a systemic problem, CAPA allows the team to plan actions and assess their effectiveness.

Neximed does not replace the classification justification or a competent authority's decision. A discussion of the process can help define how to manage the resulting tasks.

What should be checked before approving classification?

Verified on 15 October 2026. Educational material on classification in the EU. The example is hypothetical and does not determine the class of a particular product.