Antibiotics provide no benefit to COVID-19 patients

The PRINCIPLE trial has found that azithromycin and doxycycline do not provide any recovery benefits for COVID-19 patients

The ‘Platform Randomised trial of INterventions against COVID-19 In older people’ (PRINCIPLE) trial has found that the commonly used antibiotics, azithromycin and doxycycline, do not reduce recovery time for COVID-19 patients.

The trial was funded by UK Research and Innovation (UKRI) and is part of the COVID-19 rapid research response from UKRI and the Department of Health and Social Care through the National Institute for Health Research.

Prevent hospital admissions

Azithromycin and doxycycline were investigated as separate treatments to test if they would help people recover more quickly from COVID-19 and prevent the need for hospital admission.

Analyses of both antibiotics concluded that there is no benefit to patients aged over 50 who received treatment at home, nor did it reduce recovery time.

Overuse of antibiotics

Professor Chris Butler from the University of Oxford and co-lead of the PRINCIPLE trial, said:

“Azithromycin and doxycycline have anti-inflammatory, anti-bacterial and possibly anti-viral effects, and so were considered as potential treatments for COVID-19 in the community.

“While we are completing the analysis of the full range of study outcomes, and in different patient groups, our findings show that a three-day course of azithromycin or a seven-day course of doxycycline has no important clinical benefit in terms of the time taken to feeling recovered, and so will not help most patients with COVID-19 in the early stages their illness.

“These are two important findings, as both azithromycin and doxycycline have been used for treating COVID-19 in the community even in the absence of suspected bacterial pneumonia, so this practice should now be re-considered – particularly because overuse of antibiotics in the community can fuel the emergence of antimicrobial resistance.”

Professor Richard Hobbs, from the University of Oxford and co-lead of the PRINCIPLE trial, said:

“While it is disappointing that neither azithromycin nor doxycycline speed-up recovery for those with COVID-19 in the community, these are both important findings which will reduce the use of ineffective antibiotics for this illness.

“This finding shows the importance of doing rigorous clinical trials in real-world settings before treatments are rolled out on a wide scale. Widespread use of treatment should not be based on laboratory studies and opinion alone. We remain incredibly grateful for the huge efforts from many patients, GP practices and other organisations in delivering this national, flagship primary care study in these challenging times.”


To provide real-time information in the pandemic, these preliminary results have been released by the trial. Full results will be made available as a peer-reviewed publication once follow-up and analysis has been completed for all participants.


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