Borderline & combination products
Borderline determinations flow from the definition of a medical device in Regulation 2(1) of the UK MDR 2002 and the definition of a medicinal product in the Human Medicines Regulations 2012. Drug-device combination product rules are in Regulation 7A of UK MDR 2002 (inserted post-Brexit). MHRA publishes borderline guidance at gov.uk/government/publications/borderline-products-guidance-for-manufacturers.
This site provides general information only and does not constitute legal or regulatory advice. Borderline and combination product determinations are highly fact-specific. Always consult MHRA guidance and a qualified regulatory professional before finalising regulatory strategy.
What is a borderline product?
A borderline product is any product that sits at the boundary between the medical device regulatory framework and another regulatory framework — most commonly:
- Medical devices and medicinal products (medicines)
- Medical devices and cosmetics
- Medical devices and biocidal products
- Medical devices and food supplements
The same physical product can fall into entirely different regulatory regimes depending on how it is presented, what claims are made, and what the manufacturer intends it to do.
The device-medicine boundary
This is the most clinically significant — and most frequently litigated — borderline question.
The principal mode of action test
The fundamental test is the principal mode of action:
- If the product achieves its principal intended action through pharmacological, immunological, or metabolic means → medicinal product regulated under the Human Medicines Regulations 2012
- If the product achieves its principal intended action through physical, mechanical, or other non-pharmacological/immunological/metabolic means → medical device regulated under UK MDR 2002
- A product may be assisted by pharmacological/immunological/metabolic means and still be a medical device, provided those means are not the principal mechanism
What "principal mode of action" means in practice
The principal mode of action is the mechanism by which the product achieves its primary intended therapeutic or diagnostic effect — not an ancillary or secondary effect.
| Product | Principal mode of action | Regulatory status |
|---|---|---|
| Coronary stent (bare metal) | Mechanical — holds vessel open | Medical device |
| Drug-eluting stent | Mechanical (principal) + pharmacological (ancillary) | Medical device (Class III) |
| Antibiotic-coated central venous catheter | Mechanical/barrier (principal) + antimicrobial (ancillary) | Medical device |
| Antibiotic injection | Pharmacological — kills bacteria systemically | Medicinal product |
| Hyaluronic acid dermal filler (cosmetic) | Mechanical — volume restoration | Not regulated as MD or medicine in GB (no Annex XVI) |
| Hyaluronic acid intra-articular injection (osteoarthritis) | Mechanical — joint lubrication | Medical device |
| Topical antiseptic cream (wound management, device function claimed) | Barrier + antimicrobial | Borderline — depends on specific claims |
| Nicotine patch | Pharmacological — nicotine delivery through skin | Medicinal product |
| Nicotine replacement gum (no NRT claim, sold as "oral care") | Borderline — may be food or medicine depending on claims | Requires case-by-case assessment |
MHRA's approach to the boundary
When a product's principal mode of action is genuinely unclear, MHRA will assess:
- The specific claims made — labelling, IFU, marketing materials, website, social media
- The scientific evidence — what does the mechanism of action evidence show is the predominant effect?
- Regulatory precedent — how have similar products been categorised previously?
- International consensus — MHRA considers EU and FDA positions, though it is not bound by them post-Brexit
Drug-device combination products
A drug-device combination product is an integral presentation of a medical device and a medicinal substance, where both components contribute to the product's purpose and the product cannot be placed on the market separately.
Examples:
- Pre-filled syringes (device containing a medicine)
- Antibiotic-eluting bone cement
- Drug-eluting stents
- Drug-coated balloons
- Intraocular lenses with sustained-release drug component
- Transdermal drug delivery patches where the patch itself has a device function
How combination products are regulated in the UK
Regulation 7A of UK MDR 2002 (inserted post-Brexit) provides that an integral combination product is regulated under the framework applicable to its principal mode of action:
If the device is the principal element (device-led):
- Regulated as a medical device under UK MDR 2002
- The classification and conformity assessment apply to the whole product
- MHRA expects the manufacturer to consult on the medicinal substance component, which must be assessed for safety and quality (though not independently licensed as a medicine)
- For a Class III combination device with an integral medicine that is a derivative of human blood or plasma, or that would be a medicinal product if used separately: the UKAB must seek an opinion from MHRA on the medicine component as part of its assessment
If the medicine is the principal element (medicine-led):
- Regulated as a medicinal product under the Human Medicines Regulations 2012
- Requires a Product Licence (marketing authorisation)
- MHRA expects the device component to meet relevant Essential Requirements (typically those relating to safety, material compatibility, and design)
Pre-filled syringes and drug delivery systems
Pre-filled syringes (PFS) are one of the most common combination product scenarios:
| Situation | Regulatory status |
|---|---|
| Empty syringe sold separately | Medical device (container/drug delivery device) |
| Pre-filled syringe with a licensed medicine | The combination is a medicinal product (medicine-led); the syringe component must meet relevant device standards |
| Drug delivery system (pen injector) sold with medicine cartridge | Typically device-led for the delivery system; medicine-led for the cartridge |
Device-cosmetic boundary
The general principle
Cosmetic products are regulated under the UK Cosmetics Regulation (Retained Regulation (EC) No 1223/2009). A product whose sole purpose is to clean, perfume, change appearance, or protect the body for cosmetic effect is a cosmetic — not a medical device — even if it has an indirect effect on health.
When cosmetics become medical devices
A cosmetic product crosses into medical device territory when:
- The manufacturer makes specific medical claims (treatment or prevention of disease)
- The product's mechanism of action goes beyond cosmetic effect to a medical purpose
| Product | Claim | Regulatory status |
|---|---|---|
| Moisturiser | "Hydrates skin, reduces visible wrinkles" | Cosmetic |
| Moisturiser | "Treats eczema, clinically proven to reduce flare frequency" | May be a medical device or medicinal product depending on mode of action |
| Sunscreen | "SPF 50 sun protection" | Cosmetic |
| Sunscreen | "Prevents skin cancer in high-risk patients" | Medicinal product claim — enforcement risk |
| Toothpaste | "Whitens teeth, freshens breath" | Cosmetic |
| Toothpaste | "Remineralises enamel, prevents caries" | May cross into medical device territory |
The Annex XVI gap in GB
In the EU, Annex XVI of EU MDR 2017/745 brings certain non-medical-purpose products — including non-corrective contact lenses, cosmetic dermal fillers, and lipolysis/body contouring equipment — into the medical device regulatory framework. The UK MDR 2002 has no equivalent provision. These products are not currently regulated as medical devices in Great Britain.
This creates a meaningful divergence: a cosmetic dermal filler manufacturer must comply with EU MDR for their EU and NI markets (Class III under Annex XVI) but faces no equivalent UK medical device requirement for the GB market.
MHRA's reform programme may address this gap. Monitor What's New for developments.
Device-biocide boundary
Biocidal products destroy or control harmful organisms (bacteria, fungi, viruses, insects) and are regulated under the UK Biocidal Products Regulation (retained EU BPR 528/2012).
A product with antimicrobial claims may be:
- A biocidal product — if intended to destroy microorganisms in the environment or on non-living surfaces for the primary purpose of disinfection
- A medical device — if the antimicrobial function is ancillary to a primary device function (e.g., an antibiotic-impregnated catheter where the catheter's physical properties are the primary mode of action)
- A medicinal product — if intended to kill microorganisms within the living human body through systemic pharmacological action
Surface disinfectants for use in clinical settings (cleaning operating theatres, decontaminating equipment) are generally biocidal products, not medical devices.
Seeking a borderline opinion from MHRA
Manufacturers with genuine uncertainty about whether their product is a medical device — or how it should be classified at the device/medicine/cosmetic boundary — can seek an informal opinion from MHRA through its pre-submission meeting service:
- Who can apply: Any manufacturer, regulatory consultant, or UKRP with a genuine borderline question
- What is provided: MHRA's informal view on the product's likely regulatory status — not a binding legal determination
- How to apply: Via MHRA's pre-submission service
- Turnaround: Variable — typically several weeks
- Cost: Fee-based for some product types
Even an informal MHRA borderline opinion, while not legally binding, provides significant confidence for regulatory strategy. If MHRA subsequently takes a different position in enforcement, the existence of a prior opinion will be relevant context.
MHRA also publishes its borderline product assessments, which manufacturers can use as reference points for similar products.
Related pages
- What is a medical device?
- What is not a medical device?
- Devices incorporating a medicinal substance
- Software & SaMD classification
- Great Britain vs Northern Ireland — Annex XVI applies in NI, not GB
Official references
| Reference | Description |
|---|---|
| UK MDR 2002, Reg 2(1) | Medical device definition |
| UK MDR 2002, Reg 7A | Drug-device combination product provisions |
| Human Medicines Regulations 2012 | Medicinal product definition and framework |
| UK Cosmetics Regulation (retained 1223/2009) | Cosmetic product framework |
| UK BPR (retained 528/2012) | Biocidal product framework |
| MHRA: Borderline products guidance | MHRA published opinions on borderline products |
| MHRA: Pre-submission meetings | How to request a borderline opinion |
| EU MDR 2017/745, Annex XVI | Non-medical purpose device provisions (EU & NI only — not GB) |