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The world's largest clinical trial of COVID-19 treatments for recovery at home, focusing on those most at risk of serious illness from COVID-19.

Image of coronaviruses, tablets and a chemical structure of colchicine. © Shutterstock & University of Oxford

The PRINCIPLE trial platform is the national urgent public health trial for primary care and aims to find treatments for COVID-19 for people at most risk of serious illness. We are looking for medicines that can help people with COVID-19 symptoms to recover at home, get better quickly and stop them needing to go to hospital. 

Unlike many trials taking place in the community, PRINCIPLE breaks the mould with an innovative remote model that recruits participants online from anywhere in the UK, as well as via more than 1000 GP practices across the UK.

Launching in March 2020, PRINCIPLE has grown to become the world's largest Covid-19 treatments trial for recovery at home in the UK, and possibly globally. Evidence from the trial has shown that the common antibiotics azithromycin and doxycycline are not generally effective treatments for Covid-19, changing clinical practice in the UK and abroad.

In April 2021, the trial was the largest globally to report interim data showing that inhaled budesonide is an effective treatment for early-stage COVID-19, and when given to patients at home the treatment can can reduce recovery time by three days.


Lead Investigators: Professor Chris Butler, Professor Richard Hobbs.

Research Group: Primary Care Clinical Trials Unit, Oxford RCGP Research & Surveillance Centre / Clinical Informatics and Health Outcomes Research Group

Funder: National Institute for Health Research, UKRI.

Learn more here