Simethicone for Gas and Bloating
For patients experiencing gas and bloating, simethicone at a minimum dose of 320 mg is the recommended treatment based on high-quality evidence, though it works only as a symptomatic agent by consolidating gas bubbles rather than addressing underlying causes. 1, 2
Mechanism and Dosing
Simethicone is an anti-foaming agent that reduces gas bubbles in the digestive tract by consolidating them to facilitate elimination, but it does not prevent gas formation or address root causes. 1, 2
The minimum effective dose is 320 mg, supported by meta-analysis of 38 trials involving 10,505 patients, primarily from colonoscopy studies but applicable to gas-related symptoms. 1, 2
The FDA-approved indication is for relief of pressure and bloating commonly referred to as gas. 3
Clinical Efficacy
Simethicone demonstrates modest efficacy for symptomatic relief of bloating and gas-related discomfort, though comparative studies show it may be inferior to other agents targeting functional bloating. 4
When combined with other agents (chitin-glucan, probiotics, or loperamide for diarrhea), simethicone shows enhanced efficacy compared to simethicone alone, suggesting its role may be best as part of combination therapy. 5, 6, 7
For isolated functional bloating without IBS, simethicone provides safe symptomatic relief but should not be expected to resolve underlying pathology. 4, 8
When Simethicone Is Insufficient
If symptoms persist despite simethicone at adequate doses (≥320 mg), escalate to targeted therapies based on the underlying condition:
For IBS with Constipation (IBS-C):
- Linaclotide 290 μg once daily is superior to placebo for abdominal bloating in 4 trials with 3,061 patients, with moderate-quality evidence. 9
- Lubiprostone 8 μg twice daily also improves bloating with fewer side effects than linaclotide (nausea vs. diarrhea). 9
For IBS with Diarrhea (IBS-D):
- Rifaximin is efficacious for global IBS-D symptoms but has limited effect on abdominal pain specifically. 9
- 5-HT3 receptor antagonists (ondansetron 4-8 mg) are likely the most efficacious for IBS-D, though constipation is a common side effect. 9
For Suspected Food Intolerance:
- A 2-week dietary restriction trial is the simplest and most economically sound diagnostic approach before considering breath testing for lactose, fructose, or sucrose intolerance. 9
Important Caveats
Simethicone works locally and is not systemically absorbed, making it extremely safe with no reported adverse events in clinical trials, but this also limits its therapeutic scope. 1, 4, 7
For severe or persistent bloating, simethicone alone is insufficient and should be part of a comprehensive treatment approach that addresses underlying causes such as SIBO, food intolerances, or functional GI disorders. 1, 9
Patients should be evaluated for aerophagia, SIBO, or functional GI disorders if symptoms persist despite adequate simethicone dosing, as these require different therapeutic approaches. 9
Do not use simethicone as a substitute for evidence-based psychological treatments in eating disorders, as addressing fullness with medication may reinforce avoidance behaviors. 10