Benefits
Infant digestive comfort: less crying and fussing in breastfed babies
In an individual-participant-data meta-analysis of four placebo-controlled trials (345 infants with colic), the strain cut crying and fussing time by about 25 minutes a day more than placebo at day 21 and made treatment success about 1.7 times as likely. The effect was large in breastfed infants and not significant in formula-fed infants. The single colic trials cited here used 100 million CFU a day for 21 days to 1 month.
Abdominal comfort in school-age children
Trials disagree. In children with functional abdominal pain, the strain cut pain episodes and intensity over 4 weeks versus placebo in one trial of 101 children and added pain-free days over 3 months in another, but in a trial of 54 children placebo worked as well. Two pooled analyses of five and seven trials found no reliable difference from placebo in pain frequency or severity, and no difference in responder rates.
Loose stools during antibiotic courses in children
Results are split. In 654 outpatient children taking amoxicillin-clavulanate, antibiotic-associated diarrhea fell from 16.7% to 7.9% at 14 days with the strain versus placebo, but in 247 hospitalized children on antibiotics it showed no benefit (11.4% vs 6.5% with placebo). A review of three trials found less diarrhea with up to 21 days of use, but not with 14 days or less. No adult trials of this strain are cited here.
Side effects during eradication therapy with a two-strain blend
This is a blend of DSM 17938 with a second strain, ATCC PTA 6475, given to 100 adults with H. pylori infection alongside drug eradication therapy, so it shows an add-on to drug treatment, not what DSM 17938 does alone. Symptom scores rose less and fewer side effects were reported (40.9% vs 62.8%) than with placebo. Eradication (75% vs 65.9%) did not differ significantly.
Bowel regularity in infants and children
In 44 infants with chronic constipation, the strain raised weekly bowel movements versus placebo without changing stool hardness, and a 589-newborn prevention trial saw more daily stools by 3 months. In older children, two trials adding it to a laxative found no benefit, and a meta-analysis of five pediatric trials found no difference in stool frequency.
Bowel regularity and bloating in adults
In 40 adults with functional constipation, 4 weeks of the strain added 2.6 bowel movements a week versus 1.0 with placebo, without changing stool consistency. In a 105-day trial in 56 adults with constipation, abdominal discomfort, pain and bloating eased versus placebo. A 12-week trial in 290 adults over 65, giving the strain with a prebiotic fiber, found no lasting symptom improvement.
Fewer infection episodes and sick days in day-care children
In a double-blind trial in 336 healthy day-care children aged 6 to 36 months, 100 million CFU daily for 3 months cut diarrhea episodes, the registered primary outcome, and respiratory infection episodes, a secondary outcome, plus doctor visits, antibiotic use and absence versus placebo. A 6-month trial in Indonesian children (500 million CFU daily in milk) found no effect on respiratory infections or WHO-defined diarrhea.
Fewer daily spit-ups in infants
Spit-up counts kept by parents are a functional outcome. In 42 infants with frequent spit-up, 100 million CFU a day for 30 days cut daily episodes versus placebo; stomach emptying on ultrasound, a lab-type measure, also sped up. Given from the first days of life, it lowered spit-ups in trials of 40 and 589 newborns. An Italian pediatric guideline finds no proof that any strain treats infant spit-up.
Breath-test findings in children taking an acid reducer
In 128 children aged 1 to 18 with reflux disease taking esomeprazole for 12 weeks, adding 100 million CFU a day left 6.2% with bacterial overgrowth on a breath test, versus 56.2% with placebo. This is a lab measure in children on a drug. Reflux symptoms were not an outcome; abdominal complaints were tallied only among children with a positive breath test.
Mechanism of action
Faster stomach emptying in infants
In infants with frequent spit-up, the strain reduced fasting stomach distension and sped stomach emptying on ultrasound compared with placebo, and spit-up frequency tracked with stomach distension. This is the proposed route for its effect on spit-up.
Shifts in infant gut bacteria
In breastfed infants with colic, 21 days of the strain raised fecal lactobacilli and lowered fecal E. coli and ammonia, changes not seen with placebo. Whether these shifts cause the drop in crying is not proven.
Regulatory T-cell markers in infants
In infants with colic given the strain for 30 days, blood FOXP3 (a regulatory T-cell marker) rose, the RORγ/FOXP3 ratio fell and fecal calprotectin decreased.
Plasmid-cured daughter strain
DSM 17938 was derived from the parent strain ATCC 55730 by removing two plasmids carrying tetracycline and lincosamide resistance genes, using methods that do not genetically modify the organism. The new strain lost those resistances and kept the parent's probiotic properties in lab tests and a human trial.
Clinical trials
Meta-analysis of 6 randomized placebo-controlled trials of L. reuteri DSM 17938 for infantile colic; the authors note heterogeneity and call for larger trials. (Xu et al. 2015, PLoS One)
423 infants with colic (213 probiotic, 210 placebo).
Treatment effectiveness rose at 2 weeks (RR 2.84, 95% CI 1.24 to 6.50) and 3 weeks (RR 2.33, 95% CI 1.38 to 3.93) but not at 4 weeks (RR 1.41, not significant). Crying time fell by 42.89 min/day at 2 weeks and 45.83 min/day at 3 weeks versus placebo. No effect on weight, length or head circumference and no serious adverse events.
Individual participant data meta-analysis of 4 double-blind randomized placebo-controlled trials of L. reuteri DSM 17938 given orally to infants with colic, with crying and fussing time and treatment success at 21 days; several authors report BioGaia fees outside the submitted work. (Sung et al. 2018, Pediatrics)
345 infants with colic (174 probiotic, 171 placebo), breastfed and formula-fed.
At day 21 the probiotic group had 25.4 fewer minutes of crying or fussing than placebo (95% CI -47.3 to -3.5) and was 1.7 times as likely to reach treatment success. Effects were large in breastfed infants (number needed to treat 2.6) but not significant in formula-fed infants, where the authors found too little data to draw conclusions.
Randomized double-blind placebo-controlled trial of L. reuteri DSM 17938, 100 million CFU a day for 21 days. (Savino et al. 2010, Pediatrics)
50 exclusively breastfed infants with colic; 46 completed.
Median crying time on day 21 was 35 vs 90 minutes a day with placebo (P=.022), and more infants halved their crying time on days 7, 14 and 21. Fecal lactobacilli rose and fecal E. coli and ammonia fell with the probiotic only. No differences in weight gain, stooling, constipation or regurgitation, and no related adverse events.
Randomized placebo-controlled trial of L. reuteri DSM 17938, 100 million CFU a day for 30 days; daily regurgitation episodes were recorded by parents (a functional outcome) and gastric emptying was measured by ultrasound (a lab-type measure). (Indrio et al. 2011, Eur J Clin Invest)
42 infants with frequent regurgitation (functional gastroesophageal reflux); 34 completed (19 probiotic, 15 placebo).
Median daily regurgitation episodes fell versus placebo (P<0.001). On ultrasound, fasting antral area shrank (P=0.01) and gastric emptying rate rose (P=0.01). Regurgitation frequency correlated with antral area (r=0.53).
Randomized double-blind placebo-controlled trial of L. reuteri DSM 17938, 5 drops (100 million CFU) a day for 4 weeks. (Garofoli et al. 2014, Int J Food Sci Nutr)
40 breastfed full-term newborns, starting before day 3 of life (20 per group).
Daily regurgitations fell by the end of treatment versus placebo (p=0.02). Salivary sIgA did not differ. Gender distribution was unbalanced between groups by chance.
Multicenter double-masked placebo-controlled randomized trial of L. reuteri DSM 17938 for 90 days from the first week of life; a prevention trial, not a treatment trial. (Indrio et al. 2014, JAMA Pediatr)
589 term newborns at 9 Italian neonatal units.
At 3 months, the probiotic group had fewer regurgitations a day (2.9 vs 4.6, P<.01), less crying (38 vs 71 minutes a day, P<.01) and more stools a day (4.2 vs 3.6, P<.01) than placebo, with estimated cost savings for families.
Randomized placebo-controlled trial of L. reuteri DSM 17938 drops (5 drops, 100 million CFU a day) in children with gastroesophageal reflux disease on esomeprazole for 12 weeks, plus a healthy control group; the placebo was bottled water; the outcome was small intestinal bacterial overgrowth on a glucose hydrogen breath test, a lab measure. (Belei et al. 2018, J Neurogastroenterol Motil)
128 children aged 1 to 18 taking esomeprazole (64 per arm), plus 120 healthy controls.
After 12 weeks, 6.2% had dysbiosis on the breath test with L. reuteri versus 56.2% with placebo (P<0.001), similar to healthy controls (5%). Abdominal complaints on a questionnaire were tallied only in children with a positive test: 23 of 36 on placebo and none of the 4 on L. reuteri.
Randomized double-blind placebo-controlled trial of DSM 17938 plus ATCC PTA 6475, not DSM 17938 alone, given before, during and after H. pylori eradication therapy, a drug co-treatment setting. (Francavilla et al. 2014, J Clin Gastroenterol)
100 H. pylori-positive adults (50 per group).
During eradication therapy, GSRS symptom scores rose less with the blend (4 vs 6.8, P<0.01) and fewer side effects were reported (40.9% vs 62.8%, P<0.04). Eradication was 75% vs 65.9%, not statistically significant.
Multicenter randomized double-blind placebo-controlled trial (PEARL) of L. reuteri DSM 17938, 2x10^8 CFU during the antibiotic course or continued for 21 days after it; per-protocol analysis only (720 enrolled, 66 dropped out); BioGaia supplied the drops and placebo free of charge, the Pediatric Probiotic Prebiotic Society in Türkiye supported the study, and three authors report BioGaia ties; NCT02765217. (Dinleyici et al. 2025, Eur J Pediatr)
654 outpatient children aged 6 months to 10 years in Türkiye with acute otitis media or acute rhinosinusitis taking amoxicillin-clavulanate (330 probiotic, 324 placebo).
Antibiotic-associated diarrhea was less common with L. reuteri than placebo at 14 days (7.9% vs 16.7%, RR 0.47), 21 days (8.8% vs 17.9%) and 56 days (9.1% vs 19.6%), all p < 0.001. The effect was seen mainly in children aged 6 to 24 months or with otitis media.
Randomized placebo-controlled trial of L. reuteri DSM 17938, 2x10^8 CFU twice daily for the duration of antibiotic treatment; the primary outcomes were diarrhea and antibiotic-associated diarrhea. (Kołodziej et al. 2019, Clin Microbiol Infect)
250 hospitalized children receiving antibiotics (median age 4 months); 247 analyzed.
No benefit on either primary outcome. By the strictest definition, the antibiotic-associated form occurred in 11.4% with L. reuteri vs 6.5% with placebo, and all cases in 20% vs 13%. No secondary outcome or adverse event rate differed.
Randomized double-blind placebo-controlled trial of L. reuteri DSM 17938 for 4 weeks plus 4 weeks follow-up, with pain rated daily on the Hicks faces scale; NCT01180556. (Weizman et al. 2016, J Pediatr)
101 children aged 6 to 15 with functional abdominal pain (Rome III); 93 analyzed.
Pain episodes fell to 1.9 vs 3.6 a week (P<.02) and pain intensity to 4.3 vs 7.2 on the Hicks faces scale (P<.01) versus placebo. No difference in school absence or other symptoms, except less perceived bloating.
Randomized placebo-controlled trial at three university hospitals in Greece, Slovenia and Poland: 2x10^8 CFU of L. reuteri DSM 17938 or placebo for 4 weeks, with follow-up to 8 weeks. (Maragkoudaki et al. 2017, Acta Paediatr)
54 children with functional abdominal pain (Rome III), mean age 9.1 years (27 per group).
Pain frequency and intensity fell from baseline in both the L. reuteri and placebo groups at 4 and 8 weeks, and the difference between groups was not significant. Pain reliever use and school or parental work absences fell only within the L. reuteri group, again without a significant difference from placebo. No side effects were recorded.
Randomized double-blind placebo-controlled trial of L. reuteri DSM 17938 or matching placebo for 4 weeks; the primary outcome was the rise in weekly bowel movements and the secondary outcome was stool consistency. (Ojetti et al. 2014, J Gastrointestin Liver Dis)
40 adults with functional constipation (Rome III).
Weekly bowel movements rose by 2.6 with L. reuteri vs 1.0 with placebo (p=0.046), reaching 5.28 vs 3.89 a week. Stool consistency did not differ.
Randomized double-blind placebo-controlled trial of L. reuteri DSM 17938, 100 million CFU a day for 3 months plus 3 months follow-up; days with diarrhea were the registered primary outcome, and respiratory tract infection days, antibiotic use, doctor visits and absence were secondary outcomes (NCT01249911). (Gutierrez-Castrellon et al. 2014, Pediatrics)
336 healthy children aged 6 to 36 months attending day care in Mexico (168 per group).
The strain reduced the frequency and duration of diarrhea and respiratory tract infection episodes at 3 and 6 months (P<.05), plus doctor visits, antibiotic use and day-care absence. No study-product adverse events were reported.