As innovation accelerates, products increasingly blur traditional regulatory lines – especially where substances, biological mechanisms or strong therapeutic claims are involved. In practice, the “borderline” problem rarely comes from the form of the product; it comes from intended purpose, and the underlying mode of action.

UK data reflects the growing operational impact. MHRA’s GOV.UK page (updated on 12 January 2026) added a May–October 2025 statistics table reporting 108 cases received, 111 cases completed, 360 online marketplace takedowns, and 1,030 external enquiries. While UK and EU frameworks differ, the signal is consistent: regulators and marketplaces expect defensible qualification decisions and act when claims drift into medicinal territory.

What “borderline” means in the EU approach

In the EU, a product may qualify as a medical device if it does not achieve its principal intended action by pharmacological, immunological or metabolic means, even though such means may assist its function in specific scenarios. MDCG 2022-5 rev.1 provides a structured way to analyse this by distinguishing specific medical purpose, principal intended action, and principal mode of action, and by stressing that qualification must align with state-of-the-art scientific data – not marketing positioning.

This becomes particularly relevant for:

  • substance-based devices, where similarity to medicines is high and certain MDR classification rules (and in some cases consultation with medicinal authorities) can affect timelines and evidence strategy;

  • device–medicine combinations, where the dominant component and regulatory pathway determine whether you are preparing a clinical investigation under MDR or a clinical trial for a medicinal product – and what “mixed” obligations apply.

The key EU documents

The European Commission’s MDCG guidance page lists the core “borderline and classification” toolbox. For clinical evidence planning, the most practical items are:

  • Manual on borderline and classification (Version 4, September 2025) – broader scope across multiple interfaces (device vs IVD, device vs medicinal product, device vs biocides) with case examples;

  • MDCG 2021-24 (device classification) – once a product is qualified as a device, correct risk class drives conformity assessment pathways and indirectly shapes clinical evidence expectations.

Impact on clinical investigations – what changes in practice?

For sponsors, CRO teams and sites, qualification is not a paperwork exercise – it sets the operating model:

  • different legal frameworks mean different approvals, documentation, safety reporting and evidence requirements;

  • stronger scientific burden of justification for mode of action and claims coherence;

  • for medicinal products with a device component, specific EU requirements apply, including those linked to MDR Article 117, as highlighted by EMA.

Key takeaways

Borderline cases are increasingly visible operationally, including marketplace interventions and high enquiry volumes. In the EU, MDCG 2022-5 rev.1 and the updated Manual provide the main interpretive backbone. Early, science-anchored qualification and a fit-for-purpose evidence strategy reduce the risk of rework, delays, and regulatory re-routing mid-project.

https://www.gov.uk/guidance/borderline-products-how-to-tell-if-your-product-is-a-medicine
https://health.ec.europa.eu/medical-devices-sector/new-regulations/guidance-mdcg-endorsed-documents-and-other-guidance_en
https://health.ec.europa.eu/document/download/b5a27717-229f-4d7a-97b1-e1c7d819e579_en?filename=mdcg_2022-5_en.pdf
https://health.ec.europa.eu/document/download/71a87df8-5ca1-4555-b453-b65bdf8de909_en?filename=md_borderline_manual_en.pdf
https://health.ec.europa.eu/document/download/2e667094-2eaf-4370-9861-d1a283210da7_en?filename=md_border-class_helsinki-proc-mdr-ivdr_en.pdf
https://health.ec.europa.eu/document/download/cbb19821-a517-4e13-bf87-fdc6ddd1782e_en?filename=mdcg_2021-24_en.pdf