Medical devices: how to comply with the legal requirements

What you need to know before you can place a medical device in the UK market.


This guidance outlines the steps you need to follow before your product can be placed in the UK market.

Definition of a medical device

You need to decide if your product is a medical device before you go through the compliance process.

According to the Medical Devices Directive (MDD), a medical device is described as any instrument, apparatus, appliance, software, material or other article used alone or combined for humans to:

  • diagnose, prevent, monitor, treat or alleviate disease
  • diagnose, monitor, treat, alleviate or compensate for an injury or handicap
  • investigate, replace or modify the anatomy or a physiological process
  • control conception

A medical device does not achieve its main intended action by pharmacological, immunological or metabolic means although it can be assisted by these.

If you are manufacturing a medical device you must follow the specific directive for your type of product as it sets out the essential requirements the product must meet in the interest of patient safety. See more information on what a medical device is in the MDD.

See the guidance on borderline products if you are unsure whether your product is a medicine or a medical device or if it overlaps.

Medical device types and their associated directive

The 3 main types of medical devices and their associated directives are:

You must meet the requirements in the relevant directive before your device can be placed in the market.

Active implantable medical devices

These types of devices are powered implants or partial implants that are left in the human body. Examples of active implantable medical devices include:

  • implantable cardiac pacemakers
  • implantable defibrillators
  • leads, electrodes, adaptors for the above
  • implantable nerve stimulators
  • bladder stimulators
  • sphincter stimulators
  • diaphragm stimulators
  • cochlear implants
  • implantable active drug administration device
  • catheters, sensors for item above
  • Implantable active monitoring devices
  • programmers, software, transmitters

Active implantable devices fall within the highest risk category in the classification system for medical devices.

In vitro diagnostic devices

This type of medical device is usually a:

  • reagent
  • reagent product
  • calibrator
  • control material, kit, instrument, apparatus
  • equipment or system intended for use in vitro to examine specimens including blood and tissue donations from the human body

Other examples of in vitro devices are blood grouping reagents, pregnancy test kits and Hepatitis B test kits. See further guidance on the legislation relating to in vitro diagnostic devices to help with the directive.

All manufacturers of IVDs must register their medical device with the relevant authority, which is MHRA in the UK.

Some IVDs may be borderline products. You can see guidance by the European Commission for more information.

General medical devices

These types of devices usually relate to most other medical devices such as:

  • first aid bandages
  • hip prostheses
  • X-ray equipment
  • ECG monitors
  • heart valves
  • dental materials
  • spectacles
  • depressors

If you are manufacturing a medical device, you must follow these guidelines alongside the relevant directive.

These regulations fall under the Consumer Protection Act 1987 and ensure medical devices meet the requirements so that they are acceptably safe to use and suitable for their intended purpose.

The route is different for custom made devices. See the guidance on custom made devices for more information.

Classification of medical devices

Medical devices are given a classification depending on the level of risk associated with them, for example the strictest control is for products with the highest risk.

General medical devices and active implantable devices

When you have established your product is a general medical device, you need to decide which class your device falls under. The categories are:

  • Class I - generally regarded as low risk
  • Class IIa - generally regarded as medium risk
  • Class IIb - generally regarded as medium risk
  • Class III - generally regarded as high risk

How a medical device is classified will depend on factors including the intended purpose of the device, how long it’s intended to be in use for and if the device:

  • is invasive/ surgically invasive
  • is implantable or active
  • contains a substance, which in its own right is considered to be a medicinal substance

Accessories to medical devices are classified separately to the device, excluding accessories to active implantable devices. See guidance by the European Commission on how to establish which classification your product falls under.

All active implantable medical devices and their accessories fall under the highest risk category (Class III).

In vitro diagnostic medical devices (IVDs)

In vitro diagnostic medical devices are categorised differently into 4 main groups, which are devices:

  • considered as general IVD medical devices
  • within the classifications stated in Annex II list A of the IVD directive
  • within the classifications stated in Annex II List B
  • for ‘self-test’ intended to be used by a person at home

Conformity assessment and CE marking

Once you have established how your device should be classified or categorised, you will need to follow the conformity assessment route to show that it has met the requirements in the associated directives.

Assessment route for general medical devices and active implantable devices

If you have decided that your medical device falls into Class II, IIb or III, or is a Class I device that is sterile or has a measurement function, you need to contact a notified body that can carry out a conformity assessment for the specific classification.

A notified body ensures manufacturers comply with the regulations including reviewing clinical and scientific data, manufacturing processes and the quality management system. If they comply the notified body will issue a CE certificate, which manufacturers can place on their device to show that it has passed the conformity assessment. See more information on the role of a notified body and the list of notified bodies.

Class I medical devices do not need to go through a conformity procedure with a notified body if they are non sterile and don’t have a measuring function as they are generally low risk. You must register all Class I devices with MHRA.

Assessment route for IVDs

You must register all IVDs with MHRA. If your product is listed in Annex II or is a self-test device, you will need to contact a notified body.

Notified bodies will need to release in vitro products with the highest risk on a batch-by-batch basis. They will need to ensure that the product meets the relevant requirements before certifying it. You can then place the CE mark on your product to demonstrate compliance and it will be ready to place in the UK market.

See the different routes to conformity for IVDs in the guidance on the directive.

The conformity route is different for devices manufactured in healthcare establishments, see the guidance on in-house manufacturer of devices for more information.

Clinical data and clinical investigations

Manufacturers must hold clinical data to support claims made for all types of medical devices. This may be based on clinical investigations and in some cases published literature, where you can demonstrate equivalence. See more information on clinical evaluations by the European Commission.

You must inform MHRA if you are planning to conduct a clinical investigation at least 60 days before starting your investigation. This does not currently apply to IVDs, although you must notify MHRA about IVDs for performance evaluations.

Post-market monitoring and surveillance

Once a medical device has been placed in the UK market, the manufacturer is responsible for monitoring the product and reporting serious adverse incidents to the competent authority, which is MHRA in the UK. See guidance on reporting adverse incidents for information on how to do this. This ensures the device is acceptably safe to use for as long as it is in use.

See how to report a non-compliant medical device if you notice any issue with a medical device placed in the UK market.

Published 16 August 2013
Last updated 26 February 2019 + show all updates
  1. Added a link to new guidance on medical devices regulation in a no deal scenario.

  2. First published.