What is a medical device?
This page is based on Regulation 2(1) of the UK Medical Devices Regulations 2002 (SI 2002/618, as amended). The definition is the starting point for determining whether your product requires MHRA compliance and UK MDR 2002 registration.
This site provides general information only and does not constitute legal or regulatory advice. Always consult the official legislation text at legislation.gov.uk and, where appropriate, a qualified regulatory professional.
The legal definition
Under Regulation 2(1) of the UK Medical Devices Regulations 2002 (UK MDR 2002), a medical device is any instrument, apparatus, appliance, software, material or other article — whether used alone or in combination — that is:
- Intended by the manufacturer to be used for human beings, and
- Intended for one or more specific medical purposes, and
- Does not achieve its principal intended action by pharmacological, immunological, or metabolic means — though it may be assisted by such means.
The medical purposes covered are:
| Purpose | Examples |
|---|---|
| Diagnosis, prevention, monitoring, treatment or alleviation of disease | Glucose monitors, MRI machines, stethoscopes |
| Diagnosis, monitoring, treatment, alleviation of or compensation for an injury or handicap | Orthopaedic implants, hearing aids, wheelchairs |
| Investigation, replacement or modification of anatomy or a physiological process | Surgical instruments, coronary stents, catheters |
| Control of conception | Intrauterine devices (IUDs), contraceptive diaphragms |
The UK MDR 2002 explicitly lists "control of conception" as a qualifying medical purpose. This reflects the original MDD 93/42/EEC definition retained post-Brexit. The EU MDR 2017/745 does not list this as a separate purpose — it is absorbed into the general definition. In practice, contraceptive devices regulated as medical devices in the EU continue to be regulated as medical devices in the UK, but the explicit legal footing differs.
Accessories to medical devices
An accessory to a medical device is regulated as a medical device in its own right. Under UK MDR 2002, an accessory is an article that:
- Is not itself a medical device, but
- Is intended by its manufacturer to be used specifically with a medical device to enable or assist the device to be used in accordance with its intended purpose.
Examples include carrying cases, calibration materials, dedicated software add-ons, and sterilisation packaging designed for a specific device.
The "intended purpose" principle
The definition turns entirely on intended purpose — what the manufacturer states the product is designed, made, and marketed to do. Under UK MDR 2002, "intended purpose" means:
the use for which the device is intended according to the data supplied by the manufacturer on the labelling, in the instructions and/or in promotional materials.
This means:
- A scalpel sold to a butcher is not a medical device. A scalpel marketed for surgical use is.
- A smartphone app that records health data for personal interest is not a medical device. An app marketed to detect atrial fibrillation and alert a clinician is.
- A UV lamp marketed for mood lighting is not a medical device. The same lamp marketed for phototherapy of psoriasis is.
Manufacturer intent is determinative — not how an end user actually uses the product.
Even if a manufacturer does not intend off-label use, if off-label use for a medical purpose is foreseeable and not explicitly disclaimed, MHRA may consider this in scope. Be precise in your intended purpose statement.
The "mode of action" exclusion
A product is not a medical device — even if it has a medical intended purpose — if it achieves its principal intended action through:
- Pharmacological means → regulated as a medicinal product under the Human Medicines Regulations 2012
- Immunological means → regulated as a medicinal product
- Metabolic means → regulated as a medicinal product
However, a device may be assisted by such means and still qualify as a medical device. This creates important borderline and combination product categories:
| Product type | Regulatory status in UK |
|---|---|
| Drug-eluting coronary stent | Medical device — mechanical action is principal; drug is ancillary |
| Antibiotic-coated wound dressing | Medical device — physical barrier/absorption is principal |
| Monoclonal antibody treatment | Medicinal product — immunological action is principal |
| Integral drug-device combination | Primary mode of action determines lead regulation; if device-led, regulated under UK MDR 2002 with MHRA involvement for the drug component |
| Bone cement with antibiotic | Medical device — structural function is principal |
For products that sit on the boundary between devices and medicines, MHRA publishes borderline guidance. Manufacturers can also request a formal opinion from MHRA on borderline classification.
Software as a medical device (SaMD)
Software is explicitly included in the UK MDR 2002 definition. Standalone software qualifies as a medical device if it:
- Is intended by its manufacturer to be used for a medical purpose, and
- Does more than merely store, archive, compress, or transmit data.
Software that takes data as input and outputs a result that informs a clinical decision — such as a diagnostic aid, risk predictor, or treatment planning tool — is very likely to qualify as a medical device. Software that simply displays or transfers data without interpretation does not.
The classification of software-as-a-medical-device follows the standard UK MDR 2002 classification rules (Rules 9–12 for active devices, plus Rule 22 for software specifically). The higher the autonomy and influence on clinical decisions, the higher the class.
See the Software & AI as a medical device page for a full treatment including the MHRA AI and machine learning guidance.
What the UK framework does not currently cover
Unlike the EU MDR 2017/745, the UK MDR 2002 does not include an equivalent of Annex XVI — the provision that brings certain non-medical-purpose devices (such as non-corrective contact lenses, cosmetic fillers, and lipolysis equipment) into the regulatory framework. These products are not currently regulated as medical devices in Great Britain.
The Medical Devices Act 2021 gives the Secretary of State broad powers to reform UK medical device regulation. MHRA's ongoing reform programme may introduce an Annex XVI equivalent in future. Monitor MHRA consultations for updates.
Key questions to ask
Before concluding your product is a medical device, work through these questions:
- Has the manufacturer made medical claims? Check labelling, IFU, marketing materials, and technical documentation.
- Is the intended user human? Veterinary devices are outside UK MDR 2002 scope.
- What is the principal mode of action? If pharmacological, immunological, or metabolic — it is likely a medicinal product, not a device.
- Is it an IVD? If the product is used in vitro to examine specimens from the human body, consider the IVD provisions (Part III, UK MDR 2002) first. See What is an IVD?.
- Does it apply to both Great Britain and Northern Ireland? The regulatory requirements differ between GB and NI. See Great Britain vs Northern Ireland.
Related pages
- What is an IVD? — IVD definition under UK MDR 2002 Part III
- What is not a medical device? — exclusions, borderlines, and lifestyle products
- Great Britain vs Northern Ireland — dual-market regulatory position post-Brexit
- Who needs to comply? — manufacturers, UKRPs, importers, distributors
- Software & AI as a medical device
Official references
| Reference | Description |
|---|---|
| UK MDR 2002, Reg 2(1) | Definition of medical device |
| UK MDR 2002, Reg 2(1) Part III | Definition of IVD medical device |
| SI 2019/791 | Medical Devices (Amendment etc.) (EU Exit) Regulations 2019 — post-Brexit amendments |
| Medical Devices Act 2021 | Powers to reform UK medical device regulation |
| MHRA guidance: Borderline products | Determining whether a product is a medical device |
| legislation.gov.uk: UK MDR 2002 | Full consolidated text of the Regulations |