Probiotics for Bloating, Gas and SIBO: What Trials Show and Where They May Worsen Symptoms
What trials show for probiotics and bloating, gas and small intestinal bacterial overgrowth (SIBO), why results depend on the strain, and the reports of symptoms getting worse.
Content last updated . This page has not been medically reviewed.
Quick answer
The evidence that probiotics ease bloating and gas is thin and depends on the strain. A 2023 review of 82 trials in irritable bowel syndrome (IBS) rated the evidence for any benefit on bloating as very low certainty. [1] For small intestinal bacterial overgrowth (SIBO), one review found probiotics lowered breath-test hydrogen and cleared SIBO more often, while another found no benefit after bariatric surgery. [2][3] One clinic reported that some people with gas, bloating and "brain fog" who took probiotics had SIBO and D-lactic acidosis. [4] This page is information only.
Check first: when bloating needs a clinician
The NHS (UK) says to see a GP if you are often bloated, or if bloating comes with unintentional weight loss or blood in your poo. [5] It lists bloating with vomiting, diarrhoea or constipation as a reason to seek urgent advice. [5] The NHS also says bloating that does not go away can be a sign of something more serious, such as ovarian cancer. [5] A probiotic should not be a reason to wait. [6] For everyday causes and steps, see bloating and gas and digestive symptoms: red flags and when to get help.What bloating, gas and SIBO are
The NHS says the most common reason for bloating is having a lot of gas in your gut. [5] The NIDDK (US) says gas enters the digestive tract when you swallow air and when bacteria in the large intestine break down certain undigested carbohydrates. [7] The American College of Gastroenterology defines SIBO as excessive numbers of bacteria in the small bowel that cause gastrointestinal symptoms. [8] SIBO is diagnosed and treated by clinicians, usually with testing; probiotics are not a substitute for that evaluation.What the evidence labels mean
We use promising but limited, mixed, insufficient evidence, evidence of possible harm in some people, and Proper evidence not found (we looked and found nothing usable). Each label applies only to the strain, product and group studied.Bloating and gas: what trials and guidelines found
| Question | What the source found | Label |
|---|---|---|
| Bloating in IBS | 82 trials, 10,332 patients. For bloating or distension there was very low certainty of benefit for combination probiotics and Bacillus strains. Certainty was low to very low across almost all analyses. [1] Adverse events were not significantly higher with probiotics in 55 trials. [1] | Insufficient evidence |
| IBS overall, guideline view | The AGA (US, 2020) recommends probiotics for IBS only in a clinical trial. Its review found 76 trials using 44 different strains or combinations. [9] NCCIH says it was not possible to say which species, strains or combinations are most likely to help. [6] | Insufficient evidence |
| Functional gas and bloating, one trial | 70 adults in India took Bacillus coagulans MTCC 5856 (2 billion spores a day, study amount) or placebo for 4 weeks. [10] Indigestion scores improved significantly more than with placebo. [10] It is one small trial of one strain. | Promising but limited |
| Bloating in constipation | A 2020 review found multispecies products, but not single-species products, reduced bloating. [11] See probiotics for constipation. | Mixed |
| Healthy adults, B. animalis subsp. lactis | No improvement in abdominal pain or bloating was found. [12] | No benefit found in that review |
SIBO: what trials found
| Question | What the source found | Label |
|---|---|---|
| Treating SIBO, 2017 review | 18 studies were eligible for analysis. [2] Probiotics cleared SIBO more often than no probiotics, reduced breath-test hydrogen and eased abdominal pain, but did not prevent SIBO. [2] | Promising but limited |
| After bariatric surgery | A review of five studies found probiotics or synbiotics gave no significant benefit for symptoms or SIBO. [3] | Insufficient evidence |
| A 179-patient trial | The intervention group got herbal antibiotics, probiotics and prebiotics on top of antibiotics and diet. Gas levels did not differ significantly, though remission was higher. [13] Because the products were combined, the probiotic's own effect cannot be separated. | Mixed |
| Comparing SIBO treatments | A 2025 network review says comparative efficacy of treatment options remains poorly characterized and its ranking should be treated as hypotheses. [14] | Insufficient evidence |
Proper evidence not found: the ACG 2020 SIBO guideline abstract we read does not describe a probiotic recommendation, and we found no guideline text we could read that recommends a named strain for SIBO. [8]
Where probiotics may make symptoms worse
A 2018 report from one centre studied 30 people with gas, bloating and brain fogginess and an intact gut, plus 8 without fogginess. [4] Everyone in the fogginess group took probiotics. [4] D-lactic acidosis, which is known to occur in short bowel syndrome, was found in 77% of the fogginess group versus 25% of the others. [4] After stopping probiotics and taking antibiotics, brain fogginess resolved and symptoms improved in 23 of 30. [4] The authors called it a syndrome "possibly related" to probiotics, SIBO and D-lactic acidosis. [4] That is a small, single-centre observation, not proof of cause, and those people stopped probiotics and took antibiotics together, so we cannot tell which step helped.D-lactate is made by some gut bacteria, and a pediatric case report describes severe neurologic impairment from D-lactic acidosis in a boy with short bowel syndrome, who, in that single case, stabilized after a probiotic mixture was introduced. [15] The two reports point in different directions, which is why anyone with short bowel syndrome or suspected SIBO should use probiotics only under specialist care. See D-lactic acidosis, brain fog and probiotics.
Related reading
Fiber and prebiotic products can also change gas; see inulin and chicory root fiber and probiotics for IBS.Frequently asked questions
Can probiotics help bloating?
Evidence is thin. For IBS, the certainty of benefit for bloating was very low, and one single-strain trial in adults with functional gas and bloating was positive but small. [1][10]
Can probiotics make bloating worse?
Trials did not find significantly more adverse events with probiotics in IBS. [1] A separate clinic report linked probiotics, SIBO and D-lactic acidosis to gas, bloating and brain fog in 30 people. [4] The cause is unproven.
Do probiotics treat SIBO?
One review found probiotics cleared SIBO more often than no probiotic and lowered breath-test hydrogen. Another found no benefit after bariatric surgery. [2][3] SIBO diagnosis and treatment belong with a clinician.
What is D-lactic acidosis?
It is a condition with brain fogginess and raised D-lactate, described mainly in short bowel syndrome. [4] A pediatric report describes severe neurologic impairment in a boy with short bowel syndrome. [15]
When should I see a doctor about bloating?
The NHS lists frequent bloating, weight loss, blood in your poo, and vomiting or a stomach ache with bloating. [5] In a US emergency, call 911.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
- Weakened immune system or serious illness. NCCIH says the risk of harm is greater in these groups, and the NHS says to talk to a doctor first. [6][16] See probiotic safety.
- Infants. The FDA warns of invasive, potentially fatal disease in preterm infants given probiotics. [17]
- Medicines. The sources we read do not describe interactions. See medicine interactions and ask a pharmacist.
- Pregnancy, breastfeeding, kidney or liver conditions, surgery. The sources we read give no specific advice. Ask a clinician or pharmacist.
- Product quality. NCCIH notes some products contain organisms other than those on the label. [6] See quality testing and certifications.
References
- Goodoory VC, et al. Efficacy of probiotics in irritable bowel syndrome: systematic review and meta-analysis. Gastroenterology. 2023;165(5):1206-18. Abstract read 2026-10-23.
- Zhong C, et al. Probiotics for preventing and treating small intestinal bacterial overgrowth: a meta-analysis and systematic review of current evidence. J Clin Gastroenterol. 2017;51(4):300-11. Abstract read 2026-10-23.
- Wagner NRF, et al. Use of probiotics and synbiotics in the treatment of small intestinal bacterial overgrowth (SIBO) and other gastrointestinal symptoms after metabolic bariatric surgery. Obes Surg. 2025;35(1):312-21. Abstract read 2026-10-23.
- Rao SSC, et al. Brain fogginess, gas and bloating: a link between SIBO, probiotics and metabolic acidosis. Clin Transl Gastroenterol. 2018;9(6):162. Abstract read 2026-10-23.
- NHS (UK). Bloating. Page last reviewed 21 January 2026. Read 2026-10-23.
- NCCIH (US National Center for Complementary and Integrative Health). Probiotics: Usefulness and Safety. Read 2026-10-23.
- NIDDK (US). Gas in the Digestive Tract. Last reviewed June 2021. Read 2026-10-23.
- Pimentel M, et al. ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth. Am J Gastroenterol. 2020;115(2):165-78. Abstract read 2026-10-23.
- Su GL, et al. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology. 2020;159(2):697-705. Full text read 2026-10-23 on a copy hosted by a Portuguese gastroenterology society; the journal page itself returned an access block.
- Majeed M, et al. The effects of Bacillus coagulans MTCC 5856 on functional gas and bloating in adults: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2023;102(9):e33109. Abstract read 2026-10-23.
- Zhang C, et al. Meta-analysis of randomized controlled trials of the effects of probiotics on functional constipation in adults. Clin Nutr. 2020;39(10):2960-69. Abstract read 2026-10-23.
- Araujo MM, et al. Effects of Bifidobacterium animalis subspecies lactis supplementation on gastrointestinal symptoms: systematic review with meta-analysis. Nutr Rev. 2022;80(6):1619-33. Abstract read 2026-10-23.
- Redondo-Cuevas L, et al. Do herbal supplements and probiotics complement antibiotics and diet in the management of SIBO? A randomized clinical trial. Nutrients. 2024;16(7):1083. Abstract read 2026-10-23.
- Zhang Q, et al. Comparative efficacy of diverse therapeutic regimens for small intestinal bacterial overgrowth: a systematic network meta-analysis. Ther Adv Gastroenterol. 2025;18:17562848251399033. Abstract read 2026-10-23.
- Yilmaz B, et al. D-lactic acidosis: successful suppression of D-lactate-producing Lactobacillus by probiotics. Pediatrics. 2018;142(3):e20180337. Abstract read 2026-10-23.
- NHS (UK). Probiotics. Page last reviewed 24 November 2022 (next review was listed as November 2025). Read 2026-10-23.
- US Food and Drug Administration. FDA Raises Concerns About Probiotic Products Sold for Use in Hospitalized Preterm Infants. News release, 26 October 2023. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.