A randomized controlled trial (RCT) published in Canadian Medical Association Journal reported that there is no effect of the use of probiotics and xylitol chewing gum to improve sore throat symptoms (as an alternative to antibiotics).

Dr Paul Little from the University of Southampton said, "Simple over-the-counter treatments could potentially limit the effects of both bacterial and viral infections and help patients to manage symptoms. This would enable self-management, potentially facilitate a quicker return to normal activities, and reduce the pressure to use antibiotics."

Evidence exists that indicates probiotics and xylitol, a birch sugar that prevents bacterial growth, can help reduce recurrence of upper respiratory tract infections. The study included 934 people in the UK during the four year study period (June 2010 to 2014), of whom 689 provided complete data for the trial.

Using a symptom diary, participants reported the number of probiotic capsules and sticks of chewing gum used each day, as well as the severity of symptoms. They studied compliant if they had taken 75% of their allotted treatment. According to that definition, 95.6% of the probiotic group and 85.9% of the gum group (84.4% of the sorbitol group and 87.4% of the xylitol group) were compliant in the first 14 days.

Patient characteristics were well balanced for the factorial groups and also for the comparison between no xylitol and xylitol. The participants had problems with recurrent infections, with more than 50% have had 2 or more episodes of a sore throat during the 3 months before the study; in addition, about 10% of participants had a prior tonsillectomy.

Researchers found no significant effect of either probiotics or xylitol on sore throat (pharyngitis) symptoms.The authors said that there were no significant differences between groups for both the xylitol and the probiotic groups, which suggests that neither intervention helped in controlling acute symptoms.

Although prior evidence suggested that probiotics and xylitol may prevent recurrence, the research team documented only a nonsignificant 15% reduction in recurrence with xylitol. The study addresses the effectiveness of 2 promising over-the-counter remedies for acute pharyngitis. However, the study findings show that neither probiotics nor xylitol is likely to have a meaningful effect on acute sore throats.