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Can Probiotics Help With Infections?

Written by Biljana Novkovic, PhD | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Biljana Novkovic, PhD | Last updated:

Certain probiotics may help the human immune system fight off different types of infection, from Candida to H. pylori and even the common cold. But how does it work, and which probiotic species have produced the best results? Read on to find out.

Benefits of Probiotics in Infection

Certain probiotic supplements may support immunity and help support conventional treatment of infections. However, probiotics should not be used in place of what your doctor prescribes, and certain people with compromised immune systems may not respond well. Talk to your doctor before starting a probiotic supplement.

Possibly Effective For

1) Against Helicobacter pylori

Frequently used probiotic strains for H. pylori infection are L. johnsonii, S. boulardii, L. acidophilus and B. animalis ssp. lactis [1].

According to some researchers, probiotics may inhibit H. pylori infection by both non-immunological and immunological mechanisms [1].

L. delbrueckii ssp. bulgaricus and S. thermophilus improved H. pylori eradication rates in infected patients [2].

L. acidophilus decreased the viability of H. pylori and increased the eradication rate in infected patients [3].

Multi-strain probiotics, including L. acidophilus/B. animalis, significantly improved H. pylori eradication rates, prevented adverse reactions, and reduced antibiotic-associated diarrhea [4].

L. gasseri suppressed H. pylori and reduced gastric mucosal inflammation in infected patients [5]. A 4-week treatment with L. gasseri-containing yogurt improved the efficacy of triple therapy in patients with H. pylori infection [6]. L. gasseri yogurt also suppressed dyspeptic symptoms in H. pylori-infected patients [7].

Fermented milk containing L. johnsonii co-administered with antibiotics was shown to have a favorable effect on H. pylori gastritis [8].

L. johnsonii inhibited H. pylori colonization in children [9, 10] and in asymptomatic volunteers [11].

A 2-week treatment with L. reuteri significantly reduced H. pylori overgrowth in otherwise healthy adults [12].

B. animalis spp. lactis and inulin significantly reduced treatment side effects and indirectly increased eradication rates by increasing patient compliance in patients with symptomatic H. pylori infection [13].

B. bifidum improved rates of upper gastrointestinal symptomatic subjects and total symptoms in patients with H. pylori infection [14].

The combined use of C. butyricum reduced the changes in the intestinal flora and decreased the incidence of gastrointestinal side effects in patients going through H. pylori eradication therapy [15, 16].

L. brevis treatment decreased H. pylori colonization in dyspeptic H. pylori patients and reduced polyamine biosynthesis [17].

B. subtilis containing probiotics improved H. pylori eradication and decreased diarrhea and total side effects when used in conjunction with triple therapy [18].

S. boulardii reduced the colonization of H. pylori in the human gastrointestinal system, but it does not seem to be able to eradicate infection when used as single therapy [19].

In patients with H. pylori infection, S. boulardii along with standard triple therapy may increase the eradication rates and decrease overall therapy-related side effects, particularly diarrhea [20, 21, 22, 23, 24, 25].

S. boulardii administered in addition to proton pump inhibitor-based triple therapy slightly lowered the incidence of nausea, vomiting, and abdominal pain and significantly lowered the incidence of stomatitis, constipation, and diarrhea in infected children [26].

S. boulardii improved anti-H. pylori therapy-associated diarrhea, epigastric discomfort, and treatment tolerability. In addition, S. boulardii decreased post-treatment dyspepsia symptoms independent of H. pylori status [27].

L. paracasei supplementation prevented bowel symptom onset in patients on long-term proton pump inhibitors [28].

Lactobacillus, Bifidobacterium, and Saccharomyces probiotics supported conventional therapies to eradicate H. pylori infections in several clinical trials.

2) Cold & Flu

When L. casei was administered to medical students undertaking an authorized nationwide examination to test their response to stress, this bacterium lowered the rate of subjects experiencing common abdominal and cold symptoms, and decreased the total number of days students experienced these symptoms [29].

In academically stressed undergraduate students, B. bifidum increased the proportion of healthy days per participant and decreased the percentage of participants reporting cold/flu during the intervention period [30].

L. casei and B. bifidum probiotics have each decreased the rate of infection with cold & flu in clinical studies of students.

Insufficient Evidence For

The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of probiotics for any of the below-listed uses. Remember to speak with a doctor before taking probiotic supplements, and never use them in place of something your doctor recommends or prescribes.

3) Immunity

Gut microbiota cooperate with the host immune system through an extensive array of signaling pathways [31].

Studies with germ-free animals show that the microbiota are necessary for the development and regulation of immunity in the gut, where it prevents the development of inappropriate inflammation [32].

According to some researchers, probiotics may modify the immune system by stimulating anti-inflammatory cytokines, downregulating proinflammatory cytokines, and modulating white blood cell responses [1].

Probiotics activated both innate and acquired immunity in humans [33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43].

L. paracasei, L. delbrueckii, L. fermentum, L. lactis, L. gasseri, B. longum, B. breve, B. animalis and other probiotics were shown to skew the Th1/Th2 balance toward Th1 [44, 45, 46, 47, 48, 49, 50, 51, 52, 53] in infections and allergies.

Probiotics may improve the human immune response against infection, possibly by reducing inflammation and modifying white blood cell activity.

Against Infections

L. paracasei prevented common infectious disease in children attending daycare [54].

L. helveticus supplementation significantly shortened the duration and decreased the number of symptoms of upper respiratory tract illness in athletes and increased their sense of vigor [55].

Fermented milk containing L. johnsonii suppressed infections in the elderly [56].

L. brevis reduced the incidence of influenza in elementary schoolchildren. The improvement was especially pronounced in unvaccinated individuals [57].

S. boulardii enhanced the immune response in pediatric acute gastroenteritis [58].

Yogurt fermented with L. lactis lowered the risk of the common cold in human subjects [59].

Fermented milk containing L. rhamnosus significantly reduced the risk of respiratory tract infections that lasted longer than three days in hospitalized children [60].

Preterm infants treated daily with L. rhamnosus in capsules, starting within one week after birth, had a significantly lower incidence of respiratory tract infections (RTIs) and rhinovirus-induced episodes in the first 2 months [60].

Consumption of L. rhamnosus reduced the occurrence of respiratory illness in children attending daycare centers [61].

Children receiving L. rhamnosus probiotics had fewer days with respiratory symptoms per month than the children in the control group [62].

Capsulated L. rhamnosus appeared to protect hospitalized patients against ventilator-associated pneumonia, mainly when caused by Gram-negative pathogens like Pseudomonas aeruginosa [60].

In cystic fibrosis patients with P. aeruginosa, long-term L. rhamnosus significantly decreased the incidence of pulmonary exacerbations and increased body weight [60].

L. casei significantly lowered the incidence and duration of upper respiratory tract infections (URTIs) in healthy middle-aged office workers [63].

Similarly, in healthy shift workers, L. casei decreased the incidence of gastrointestinal and respiratory common infectious disease (CIDs), increased the time to the first occurrence of CID, and reduced the total number of CIDs in the subgroup of smokers. In the course of CID, the total duration of fever was lower and an increase in leukocyte, neutrophil, and natural killer (NK) cell counts and activity was observed [64].

L. casei also lowered the incidence of common infectious diseases (CIDs) in children [65], decreased the duration of CID, and especially upper-respiratory-tract infections (URTI) such as rhinopharyngitis in the elderly [66].

In athletic men and women who engaged in endurance-based physical activities in winter, L. casei lowered the proportion of subjects who experienced 1 or more weeks with upper-respiratory-tract infection (URTI) symptoms and decreased the number of URTI episodes [67].

When healthy subjects took L. gasseri, B. longum, and B. bifidum in the winter, common cold episodes shortened by almost 2 days and reduced the severity of symptoms [68].

L. acidophilus, B. bifidum and B. animalis plus vitamin C reduced the incidence rate of upper respiratory tract infection, the number of days with symptoms and the absence from preschool in children [69].

According to one study, a synbiotic containing L. acidophilus, B. infantis, and B. bifidum may provide effective control of respiratory infection and wheezing frequency in children under five years old [70].

The intake of yogurt fermented with L. delbrueckii ssp. bulgaricus increased the activity of natural killer cells and reduced the risk of catching a common cold in the elderly [71].

L. acidophilus suppressed all 74 gram-negative and 16 of the gram-positive bacteria commonly found in burn wounds. According to the authors, it may therefore be useful in the prevention of burn wound infections [72].

L. fermentum reduced the duration and severity of respiratory illness in highly trained distance runners [73].

L. fermentum reduced the severity of gastrointestinal and respiratory illness symptoms in male but not female cyclists [74].

L. fermentum reduced gastrointestinal and upper respiratory tract infections in infants [75, 76].

Oral administration of L. fermentum potentiated the immunologic response to the flu vaccine. According to some researchers, this probiotic may enhance systemic protection by increasing the Th1 response and virus-neutralizing antibodies. The incidence of an influenza-like illness in the 5 months after vaccination was decreased in the group that consumed this probiotic [47, 48].

B. longum reduced the incidence of influenza and fever in subjects with influenza vaccination [77].

B. longum fed infants showed a trend toward fewer respiratory tract infections [78].

B. longum ssp. infantis appeared to trigger an anti-poliovirus response in infants [79].

B. breve significantly inhibited rotavirus multiplication and prevented rotavirus infection in infants [80].

B. animalis ssp. lactis reduced days with cold/flu in young healthy adults [81].

Infants and children receiving B. animalis ssp. lactis experienced fewer respiratory tract infections [82, 83].

S. boulardii reduced E. coli numbers in children [84].

In one study, S. boulardii was as effective against B. hominis infection in children as metronidazole [85].

S. boulardii was effective in treating giardiasis when combined with metronidazole therapy in adult patients [86].

The addition of S. boulardii to metronidazole in amebiasis significantly decreased the duration of (bloody) diarrhea and enhanced clearance of cysts in children [87]. It also decreased the duration of symptoms and cyst passage in adults [88].

Prophylactic S. boulardii supplementation appeared to be as effective as nystatin in reducing fungal colonization and invasive fungal infection; it also seemed to be more effective in reducing the incidence of clinical sepsis and the number of sepsis attacks. S. boulardii also had a favorable effect on feeding intolerance in very low birth weight infants [89].

B. subtilis decreased the frequency of respiratory infections in elderly subjects [90].

B. subtilis inhibited disease transmission in patients with acute non-typhoid Salmonella gastroenteritis [91].

Metabolites of B. subtilis decreased the resistance of urogenital pathogenic microflora to antibiotics in patients with urinary tract infections, resulting in accelerated elimination [92].

Probiotics appeared to be effective in the treatment and prevention of urogenital infections in women as alternatives or co-treatments. They also appeared to be effective for the treatment and prevention of bacterial vaginosis, prevention of recurrences of candidiasis and urinary tract infections, and clearing of human papillomavirus lesions. No study reported significant adverse events related to probiotic intervention [93].

Probiotic supplementation with vaginal L. rhamnosus inhibited bacteria growth, especially after antibiotic therapy [94].

According to some researchers, L. rhamnosus vaginal tablets may be a reliable and safe topical treatment to reduce the bacterial vaginosis recurrence rate [95].

Daily ingestion yogurt enriched with L. acidophilus may reduce the episodes of bacterial vaginosis [96]. Treatment of patients with bacterial vaginosis with L. acidophilus contributed to the restoration of a normal vaginal environment [97].

L. fermentum and L. plantarum significantly reduced bacterial vaginosis in women [98].

L. crispatus reduced recurrent urinary tract infections in premenopausal women [99].

L. crispatus inhibited Chlamydia trachomatis, the most common sexually transmitted bacterial pathogen, in human epithelial cells and macrophages [100, 101].

Cervicovaginal mucus with high L. crispatus concentrations may trap the HIV virus and prevent (or delay) systemic infection [102].

B. coagulans reduced vaginosis symptoms in women when co-administered with antibiotics [103].

See individual probiotic posts for more information and animal studies.

A variety of probiotics have prevented infections or supported conventional treatments in many clinical trials.

4) HIV-Positive Patients

Treatment with S. boulardii decreased microbial translocation (LBP) and inflammation parameters in HIV-1-infected patients with long-term virologic suppression [104].

5) Against Candida

Clinical trials have suggested that probiotics may reduce oral, vaginal, and enteric colonization by Candida pathogens. Probiotics alleviated clinical signs and symptoms, and, in some cases, reduced the incidence of invasive fungal infection in critically ill patients [105].

In patients with vulvovaginal candidiasis, L. plantarum reduced vaginal discomfort after conventional treatment, improved vaginal bacteria content, and restored vaginal pH [106].

In a clinical trial, L. plantarum use was associated with a three-fold reduced risk of recurrence of vulvovaginal candidiasis [107].

L. fermentum and L. acidophilus maintained the vaginal biofilm and hindered persistent vulvovaginal infection caused by Candida in women [108].

L. reuteri alone or with L. rhamnosus inhibited the growth of Candida in the vagina [109, 110].

L. rhamnosus may prevent enteric colonization by Candida species in preterm neonates [60].

Oral L. reuteri supplementation suppressed candidiasis as effectively as nystatin in preterm infants. It was also more effective at reducing the incidence of sepsis [111, 112].

L. reuteri lozenges were shown to fight oral candida in a study of older patients [113].

S. cerevisiae, when administered orally, colonized the bowel of healthy volunteers; some researchers believe it could compete with and potentially replace resident Candida species [114].

Vaginal administration of S. cerevisiae positively influenced the course of vaginal candidiasis by accelerating the clearance of Candida [115].

See individual probiotic posts for more information and animal studies.

Lactobacillus and Saccharomyces probiotics prevented or helped eradicate infection with Candida in several clinical trials.


Many species of probiotic bacteria, most notably Lactobacillus, Bifidobacterium, and Saccharomyces species, have reduced rates of infection or supported conventional therapies against common and uncommon illnesses.

Some researchers believe that these benefits emerge from an interaction between the gut flora and the immune system; certain probiotics appear to decrease inflammatory signals and modify white blood cell activity.

Further Reading

We’ve compiled deep dives into each potential benefit of probiotics. Check them out here:

About the Author

Biljana Novkovic

Biljana Novkovic

Biljana received her PhD from Hokkaido University.
Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science and health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.


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