Preventing acute upper respiratory tract infections with probiotics?

The Bottom Line

  • Acute upper respiratory tract infections (URTIs), such as croup, the common cold, tonsillitis, and sinus infections, are major sources of illness.
  • Probiotics—also known as the "good” bacteria—appear more effective than placebo or no treatment at preventing acute URTIs in people with a healthy immune system. More high-quality research is needed to improve the current evidence base.  
  • Considering probiotics? First, consult your health care team about their use as a preventative strategy.  

Croup, the common cold, tonsillitis, and sinus infections (1-5). Although generally mild and short-lived, we all want to avoid them and the disruptive symptoms they bring (1). Besides being unwelcome, what do these conditions have in common? Well, they are all types of acute upper respiratory tract infections (URTIs), which happen to be a significant source of illness. Children and older adults are especially vulnerable to acute URTIs (1-5).

The number of upper respiratory infections seen each year is substantial. In 2019 alone, there were 17.2 billion new cases across the globe (2). The question then becomes, is there anything we can do to protect ourselves from getting them?

Probiotics, considered “good” bacteria that promote gut health, have been a strategy of interest for the prevention of respiratory tract infections for many years. Their consumption, via foods containing them or supplements, is also rising. A recent systematic review updated the evidence base on whether probiotics can thwart the development of acute URTIs in children, adults, and older adults with a healthy immune system (1).

What the research tells us

Compared with a placebo or no treatment, probiotics—most often consumed with milkā€based food, via capsules, or through a powder formulation in this review—show the potential for several benefits in people with healthy immune systems.

First, probiotic consumption may lower the number of people diagnosed with at least one URTI and probably decreases the number diagnosed with at least three URTIs. Second, when it comes to how long an “episode” of acute URTIs lasts, probiotics my decrease the average duration by around 1.22 days (1). With the overuse of antibiotics having a significant role in the growing issue of antibiotic resistance, here we see that probiotics may also decrease the number of people who use prescribed antibiotics for an acute URTI (1;6;7). Last but not least, in comparison to placebo or no treatment, probiotics are most often associated with minor side effects such as gassiness, bowel pain, vomiting, and diarrhea (1).

Overall, our confidence in these findings ranges from low to moderate. More high-quality studies that feature a greater number of participants are needed to increase our certainty in these results and our understanding of the potential effects, especially in older adults (1). 

If you are considering probiotics as a preventative strategy against acute URTIs or in general, remember to consult your health care team first. Together you can discuss the different ways probiotics can be consumed and choose the best and safest option for you.    

Featured Resources

Get the latest content first. Sign up for free weekly email alerts.
Author Details


  1. Zhao Y, Dong BR, Hao Q. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2022; 8:CD006895. doi: 10.1002/14651858.CD006895.pub4.
  2. Institute for Health Metrics and Evaluation. Upper respiratory infections — Level 3 cause. [Internet] 2023. [cited January 2023]. Available from
  3. Duijvestijn YC, Mourdi N, Smucny J, et al. Acetylcysteine and carbocysteine for acute upper and lower respiratory tract infections in paediatric patients without chronic broncho-pulmonary disease. Cochrane Database Syst Rev. 2009; 1:CD003124. doi: 10.1002/14651858.CD003124.pub3.
  4. Kassel JC, King D, Spurling GK. Saline nasal irrigation for acute upper respiratory tract infections. Cochrane Database Syst Rev. 2010; 3:CD006821. doi: 10.1002/14651858.CD006821.pub2.
  5. Liberati A, D'Amico R, Pifferi S, et al. Antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving intensive care. Cochrane Database Syst Rev. 2009; 4:CD000022. doi: 10.1002/14651858.CD000022.pub2.
  6. Andersson DI, Balaban NQ, Baquero F, et al. Antibiotic resistance: Turning evolutionary principles into clinical reality. FEMS Microbiol Rev. 2020; 44(2):171-188. doi: 10.1093/femsre/fuaa001.
  7. Woappi Y, Gabani P, Singh A, et al. Antibiotrophs: The complexity of antibiotic-subsisting and antibiotic-resistant microorganisms. Crit Rev Microbiol. 2016; 42(1):17-30. doi: 10.3109/1040841X.2013.875982. 

DISCLAIMER: These summaries are provided for informational purposes only. They are not a substitute for advice from your own health care professional. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the McMaster Optimal Aging Portal (

Many of our Blog Posts were written before the COVID-19 pandemic and thus do not necessarily reflect the latest public health recommendations. While the content of new and old blogs identify activities that support optimal aging, it is important to defer to the most current public health recommendations. Some of the activities suggested within these blogs may need to be modified or avoided altogether to comply with changing public health recommendations. To view the latest updates from the Public Health Agency of Canada, please visit their website.