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The University of Southampton
Southampton Clinical Trials Unit

The COAT Study

COAT logo

A Study for Patients Who Are Prescribed Antibiotics for Cellulitis


Research sites

Research Sites

Information and resources for research sites who are running the COAT study.



Information for study participants and patients interested in taking part.

What is the COAT study?

Trial status - Recruiting

Background and study aim

Cellulitis is a deep infection of the skin and subcutaneous tissues and most often occurs in the legs. It is a painful condition that is associated with inflammation and swelling of the site, and often systemic symptoms such as fever, headache, muscle aches, malaise, and fatigue. Patients report feeling unwell and that it has a significant impact on their mobility and ability to carry out their usual activities.

NICE guidelines recommend oral flucloxacillin 500–1000 mg four times daily for 5-7 days as first-line treatment for most patients with cellulitis in the community, but most prescriptions are dispensed for a 7-day course.

Research sites open - 37

We will be assessing the effectiveness and safety of a 5-day treatment versus the standard 7-day treatment. We also aim to evaluate the cost-consequences of a shorter course from an NHS and personal perspective.

Who can participate?

Adults presenting in primary care with unilateral cellulitis of the leg.

What does the study involve?

Participants will be randomly allocated to one of two groups. In addition to usual care, participants will either be assigned to a 5-day oral flucloxacillin course or a standard 7-day flucloxacillin course.

Patients recruited - 43

Participants will be prescribed a 5-day course of oral flucloxacillin, and two additional tablets will be posted to the participants which will either be the antibiotic or a placebo tablet.

Participants will be asked to fill out daily questionnaires and express their experiences with the shortened course and taking part in the trial.

What are the possible benefits and risks of participating?

Benefits include that participants may see an improvement in their cellulitis and avoid needing to use antibiotics or for longer than is necessary. Participants will be helping to further our knowledge of how to treat patients with cellulitis and this will benefit others with the same condition in the future. However, possible risks include the listed side effects of oral flucloxacillin, and the need to fill out questionnaires that would not normally be asked of them if they were not part of the trial.

Research Sites

This page provides information for researchers and research teams at sites taking part in the COAT cellulitis study. If you are a study participant, or a patient wanting to find out more information about joining the study, please click here.


1)    Can non trial team recruit into the trial?

Eligibility can be assessed by any clinician that has experience in diagnosing and managing cellulitis, this can include AMPs who fulfil this criteria. In order to assess eligibility clinicians must watch the training video on assessing eligibility and identifying true penicillin allergies, however staff members ONLY delegated this task do not need to have GCP training. The clinician can then prescribe the potential patient 5 days of flucloxacillin and refer them onto the trial team who can consent the patient.

2)    What happens if there is no one who has been delegated to recruit working that day?

Clinicians who are delegated to assess eligibility can determine if the patient is eligible and prescribe the 5 days of flucloxacillin. The trial team can then pick this up the following day. Please note when doing this it is important that the central team receive the ICF and the proforma as soon as possible to allow time for the IMP to be sent to the patient.

3)    What happens if the patient doesn’t receive the extra 2 days of IMP in time?

When initially calling the patient the central trial team will explain the process for sending the IMP to the patient and ask that they call the central team if they haven’t received the IMP within 2-3 days. The central team will then send out another bottle of the IMP via a courier service. The patient will be advised to that if both bottles of the IMP arrive, they must only use 1 bottle. If the central team become aware after the initial 5 days the participant will be advised that they are still in the study and asked to continue to complete the questionnaires. The central team will inform the site when this occurs.

4)    Does the patient need to be seen face to face?

Yes – at this time we are requesting that all patients are seen face to face to confirm the diagnosis and allow for the completion of the baseline CRF. However, the initial triage can be done remotely if this is the current practice.  

5)    How long will the study be recruiting for?

The study will be recruiting for 20 months

6)    What is the recruitment rate?

The target recruitment is 1 patient per site per month, although this is not a maximum and sites can recruit more than this.

7)    Can the paper CRFs be completed from home, or will patients need to come back to the surgery?

Patients completing the CRFs on paper not via the website will be sent the paper copies with the IMP by the central trial team. This will also include free post envelopes for them to return the questionnaires to the CTU. This data will be inputted by the central team onto openclinica.


Contacting the study team

If you have a query about the study and need to contact the study team, please email

You can find details of the Trial Management team here.

If you need to report an SAE, please email

Patients and potential study participants

This page provides information for study participants and patients interested in finding out more or joining the COAT cellulitis study. If you are a researcher or part of a research team at a site taking part in the COAT study, please click here.


Watch Professor Nick Francis introducing the COAT study

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