Plain English Summary
Background and study aims
Upper respiratory tract illness (URTI) is the most common respiratory illness experienced by the general population and sore throat is the most common URTI managed in the NHS, costing the NHS an estimated £25 million in consultations alone. Antibiotic use for respiratory tract illnesses has decreased since 1997 but is still double the rate of other Northern European countries, and costs the NHS an additional £6-12 million in prescribing costs per annum. Xylitol (used in some sugar-free gum) is a birch sugar, and causes local 'bacterial interference' by inhibiting the growth and adherence of bacteria to the throat. Sorbitol has no such effect and will be used as a 'placebo' (dummy) gum. Probiotics, which are also available commercially, are benign non-pathogenic bacteria and may also act through local 'bacterial interference' by a different mechanism and may also have an effect on non-specific general activation of the immune system. Although there are studies that support the use of both xylitol and probiotics in the management of recurrent infections, this evidence needs confirming, and we particularly need evidence about their effectiveness for either symptoms or recurrence of sore throat. In addition there is no clear evidence concerning the effect of chewing any kind of gum on the symptoms of sore throat. The effectiveness of chewing xylitol and probiotics in URTIs requires urgent clarification both for the general public and for the health service. Since probiotics and xylitol act via different mechanisms, a study is needed to assess the possible interaction of both interventions together. This study aims to investigate the effect of xylitol and probiotics on symptoms and recurrence of sore throat.
Who can participate?
Patients over the age of 16, presenting with acute sore throat.
What does the study involve?
We will provide participants with instructions and randomly allocate them to receive a treatment pack containing 3 months' supply of either just probiotic capsules (to take one capsule daily) or probiotic capsules and chewing gum (to chew five pieces a day). As some people get better just because they are taking something they believe to be helpful (a placebo), some of our packs have pretend treatments in them - they will look and taste the same as the real thing and participants won't know which one they've got until the end of the study.
What are the possible benefits and risks of participating?
Not provided at time of registration.
Where is the study run from?
The study was lead and run by the trial management team in Southampton, and we recruited participants from 83 practices from Land's End to Ipswich.
When is the study starting and how long is it expected to run for?
The study will run from November 2008 to January 2015. Recruitment closed in July 2014.
Who is funding the study?
National Institute for Health Research (NIHR) (UK).
Who is the main contact?
Ms Tammy Thomas
A primary care randomised controlled trial of probiotics, xylitol and sorbitol for acute sore throat
This study aims to investigate the effect of xylitol and probiotics on symptoms and recurrence of sore throat.
Patients will be approached by either advertising in the practice, when seeing their doctor/nurse (who will provide information to the patient with the consent form) or by writing to patients with known recurrent sore throat identified from a database search. Patients who agree to take part will be allocated treatment packs in numerical order provided by the investigators with the surgery recording ID numbers.
On 21/08/2014 the overall trial end date was changed from 01/07/2011 to 01/01/2015.
Southampton and South West Hampshire REC, 28/02/2005, ref: 05/Q1702/11
Randomised interventional treatment trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Topic: Primary Care Research Network for England; Subtopic: Not Assigned; Disease: All Diseases
Probiotics, sorbitol and xylitol for acute sore throat. Patients randomised to probiotics/placebo will be required to take one capsule per day for 3 months. Patients randomised to chew active/placebo gum will be asked to chew five pieces per day (for 5 minutes) for 3 months. All treatment groups will be followed up for a further 3 months.
Follow-up length: 6 months
Study entry: single randomisation only
Primary outcome measures
The mean score for sore throat and difficulty swallowing during 2 - 5 days after presentation
Secondary outcome measures
1. Time to resolution of sore throat
2. Time taken off work or unable to do normal activities
3. Satisfaction with treatment
Overall trial start date
Overall trial end date
Participant inclusion criteria
1. Presenting with acute sore throat
2. Over the age of 16 years, either sex
Target number of participants
Planned Sample Size: 401; UK Sample Size: 401
Participant exclusion criteria
1. History suggestive of quinsy
2. Previous rheumatic fever, glomerulonephritis
4. Allergy to xylitol, sorbitol or probiotics
5. Patients unwilling or unable to self medicate with gum or probiotics for the duration of the study or complete outcome measures
6. Subjects with serious chronic disorders where antibiotics are automatically needed (e.g. cystic fibrosis)
7. Suspected pregnancy
8. Immune deficiency
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Aldermoor Health Centre
University of Southampton (UK)
National Institute for Health Research (NIHR) (UK) - Programme Grant for Applied Research (PGfAR) (ref: RP-PG-0407-10098)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Results - basic reporting