Run a clinical trial of a medicine in the UK

These rules apply across the UK. They bind the sponsor of a trial, meaning the person or organisation that takes responsibility for starting, managing and financing it, whether commercial or academic. Every trial must have one, or two or more acting jointly. A sponsor must be established in the UK or in a country on the approved country list, or have a legal representative who is.

Check that the rules cover your study

The rules cover any investigation in human participants, other than a non-interventional trial, that is meant to discover or verify the effects of a medicinal product, identify its adverse reactions, or study how the body absorbs, distributes, metabolises and excretes it, in order to ascertain its safety or efficacy. The Medicines and Healthcare products Regulatory Agency (MHRA) publishes an algorithm that helps you decide whether your study is a clinical trial of a medicinal product. Trials of medical devices fall under separate rules.

Get approval before you start

You must not start a trial until it has a joint clinical trial approval, which is a favourable opinion from a research ethics committee and an authorisation from the MHRA. You apply once, through the Integrated Research Application System (IRAS), and the MHRA and an ethics committee review the application in parallel. Separate applications are allowed only in exceptional circumstances, with the MHRA's written agreement in advance.

The review runs on fixed timescales.

• Within 7 calendar days of submission, you are told whether the application is valid or has deficiencies to put right.
• Within 30 calendar days of validation, you receive one combined decision: approved, approved with conditions, or not approved with the grounds and the further information needed.
• If it is not approved, you have 60 calendar days to send the further information through IRAS, and a decision follows within 10 calendar days.
• If an expert committee or specialist group is consulted, the first 30 days extend by 90 days.

You can appeal an MHRA refusal or the conditions it attaches by writing to the Health Research Authority within 28 calendar days. Fees apply to an application, and the cover letter must carry the purchase order number for invoicing.

Some trials need further approvals as well. For example, a trial using radioactive substances needs approval from the Administration of Radioactive Substances Advisory Committee. You, as sponsor, must make sure you have them all before the trial starts.

Use the notifiable trial route if you qualify

A notifiable trial receives automatic authorisation from the MHRA, normally confirmed within 14 calendar days of validation. A trial is notifiable only if it meets all of the following.

• As far as you know after reasonable enquiries, there are no significant safety concerns with any investigational medicinal product.
• No participant is under 18, pregnant or breastfeeding.
• No product is an advanced therapy medicinal product or is being used in humans for the first time.
• The trial meets at least one of three conditions. Every product is authorised in the UK and used in line with that authorisation or established clinical practice. Or the same product was approved in a UK trial within the previous 2 years at the same or a higher dose, frequency and duration, with the same manufacturing process, route and indication. Or the licensing authority in the EU, an EEA state or the USA has approved the trial.

You apply through IRAS with the same documents as any other trial, plus the confirmation of notifiable trial criteria form, and the cover letter must say the trial is notifiable. The ethics committee reviews it in the usual way, and the trial cannot start until you have the combined decision. The MHRA can still choose a full review, and if it does it tells you within 14 calendar days of validation.

Follow good clinical practice

Get informed consent

Report safety events

Submit SUSAR reports through ICSR Submissions or the MHRA Gateway in E2B(R3) format.

Register the trial and publish the results

End the trial and keep the records

Tell the MHRA and the ethics committee in writing that the trial has ended, within 90 calendar days if it ended as the protocol planned, or within 15 calendar days if it stopped early. Approval lapses if no participant has been recruited within 2 years of approval. You can ask the MHRA for an extension of up to 36 months, and then a further extension of up to 24 months.

These rules apply to trials whose approval application was submitted on or after 28 April 2026. A trial whose application went in earlier is an old rules trial, and its registration and results duties are as the transitional guidance sets out.

Know what happens if you do not comply

It is a criminal offence to start a trial without approval, or to breach the duties to follow good clinical practice, register the trial, report safety events and urgent safety measures, send annual safety reports, notify the end of the trial, or keep the trial master file. Since 28 April 2026 the MHRA can also issue infringement notices for the same breaches.