Lactobacillus reuteri Dosing Recommendations
For healthy adults, use Lactobacillus reuteri at 1 × 10⁸ to 1 × 10⁹ CFU twice daily; for infants with colic, use L. reuteri DSM 17938 at 1 × 10⁸ CFU once daily; avoid use entirely in immunocompromised patients and pregnant women should only use it prenatally at 1 × 10⁸ CFU daily during the last 4 weeks of pregnancy for colic prevention in their future infants.
Healthy Adults
- Administer L. reuteri ATCC 55730 at 1 × 10⁹ CFU twice daily for antibiotic-associated diarrhea prevention, continuing throughout the antibiotic course plus 5-7 days post-completion 1, 2
- This dosing significantly reduces diarrhea frequency from 50% to 7.7% in hospitalized adults receiving antibiotics 1
- For general gastrointestinal health maintenance, use 1 × 10⁹ CFU daily as a single dose 3
- The strain survives gastrointestinal transit effectively at these doses when delivered in low-fat spread or capsule formulations 3
- Treatment duration of 4 weeks has demonstrated safety and tolerability with no adverse effects 1
- Higher doses up to 2.9 × 10⁹ CFU twice daily (total 5.8 × 10⁹ CFU/day) for 9 weeks show excellent safety profiles with no clinically significant hematological or biochemical abnormalities 4
Infants (Term, Healthy)
- For infantile colic in breastfed infants, use L. reuteri DSM 17938 at 1 × 10⁸ CFU once daily for 28 days 5, 6, 7
- This is the only probiotic strain with strong evidence specifically for colic treatment 7
- Expect clinical response within 7 days, with median crying time reduction from 159 minutes/day to 51 minutes/day by day 28 5
- Response rate reaches 95% by day 28 in breastfed infants 5
- Evidence is less supportive for formula-fed infants, so prioritize use in breastfed populations 7
- Administer as liquid drops, which is the standard formulation for this age group 6
Extremely Preterm Infants (<1,000g, <28 weeks)
- Use L. reuteri DSM 17938 at 1.25 × 10⁸ CFU once daily from birth until 36 weeks postmenstrual age 6
- This dosing improves head growth and weight gain in extremely low birth weight infants 6
- However, exercise extreme caution in this population due to risk of bacteremia, particularly if central venous catheters are present 7, 2
- Prioritize pharmaceutical-grade products over dietary supplements, as manufacturing contaminants have caused fatal infections in preterm infants 7
Pregnant Women (Prenatal Administration)
- Administer L. reuteri LR92 DSM 26866 at 1 × 10⁸ CFU once daily during the last 4 weeks of pregnancy to prevent infantile colic in the newborn 8
- This prenatal regimen reduces the likelihood of infantile colic by 2.36-fold (95% CI 1.18-4.73) 8
- It also significantly reduces colic severity when it does occur 8
- This is a preventive strategy, not a treatment for maternal conditions 8
Absolute Contraindications
- Never administer L. reuteri or any probiotic to immunocompromised patients due to bacteremia risk 6, 2
- Avoid in critically ill patients with indwelling central venous catheters 7, 2
- Avoid in patients with cardiac valvular disease 7, 2
- Avoid in patients with short-gut syndrome 7, 2
Critical Dosing Pitfalls
- Strain specificity is absolute—L. reuteri DSM 17938 and L. reuteri ATCC 55730 are different strains with different evidence bases and should not be substituted 6, 7
- Verify products contain viable (live) bacteria at specified CFU counts, as product quality varies widely 6
- Dead bacteria content inversely correlates with product quality 7
- Products deposited at biodepositories like ATCC provide better quality assurance 7