Simeticone

Drugs for functional bowel disorders. Antifoaming agents

ATC code: A03AX13

Brand names: Gas-X, Mylicon, Phazyme

Updated 21 Jul 2026 · Methodology

Indications

Functional bloating

Adjunct

In functional bloating, simeticone may reduce symptom severity in short courses. The evidence base is limited to small RCTs; and mention the drug as a symptomatic option without first-line status. Effect is unpredictable: some patients report significant relief, others none.

Course limited to 2–4 weeks. If symptoms persist, reassess the diagnosis and work up for SIBO, lactase deficiency, celiac disease and IBS.

Sources

NICE: Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management (CG184) (2019)

ICD-10: R14 · ICD-11: DD91.3

Preparation for endoscopy or ultrasound

Adjunct

Simeticone is used as a standard component of preparation for endoscopic (EGD, colonoscopy) and abdominal ultrasound studies. It reduces foam and gas in the lumen, improves mucosal visualization and increases diagnostic accuracy. Dose 80–240 mg 20–30 minutes before the procedure. Meta-analyses confirm improved examination quality in colonoscopy and EGD.

Sources

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Gastroesophageal reflux disease

Not recommended

Simethicone is an anti-foaming agent that lowers the surface tension of gas bubbles in the gut, and it is sometimes offered for GERD, reflux and heartburn. For this use the benefit has not been shown: there is no convincing evidence that simethicone reduces reflux or heals the esophagus. GERD responds to other measures – proton pump inhibitors, changes in diet and lifestyle, and a medical check-up when needed. The substance itself is harmless in this role, but it should not be used instead of treatment with proven benefit, or the right therapy may be missed.

Sources

ACG: ACG Clinical Guideline for the Diagnosis and Management of Gastroesophageal Reflux Disease (2022)

ICD-10: K21 · ICD-11: DA22

Infantile colic

Not recommended

Simethicone is an antifoaming agent: it lowers the surface tension of gas bubbles in the gut, so it is offered to babies for colic to ease bloating and crying. For this use no convincing benefit has been shown, and in good-quality studies simethicone eased colic no better than placebo. Infant colic responds more to reassurance and parental support, soothing techniques, and, when cow's milk protein allergy is suspected, a feeding change guided by the pediatrician. Simethicone is harmless here, but do not rely on it instead of approaches with proven benefit, since that can delay care for a condition that needs treatment.

Sources

NASPGHAN: Functional Gastrointestinal Disorders in Infants and Toddlers: Position Paper (2017)

ICD-10: R10.4 · ICD-11: DD93.1

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

Reduces surface tension of gas bubbles in the GI tract and promotes their coalescence. The freed gas is expelled naturally or absorbed by the mucosa. The drug is not systemically absorbed and acts only locally in the GI lumen. Chemically inert and does not react with other drugs.

Safety

Contraindications

Hypersensitivity to simeticone or excipients
Bowel obstruction

Serious adverse effects

Anaphylactic reactions (extremely rare)

Common adverse effects

Allergic reactions (urticaria, rash)

Pregnancy: can you take Simeticone?

AEMPS summary of product characteristics (section 4.6): there are no data on the use of simethicone in pregnant women. Because simethicone is not absorbed from the gastrointestinal tract, there is no evidence of harm in pregnant women, and it can be used during pregnancy.

Breastfeeding: can you take Simeticone?

Not absorbed, does not enter milk in active form. Compatible with breastfeeding.

Calculate RID Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Taken with or after meals and at bedtime. Drops are shaken thoroughly before use. For preparation for EGD or ultrasound – 20–30 minutes before the procedure.

Monitoring

No specific monitoring required – the drug is not absorbed. If symptoms persist beyond 4 weeks, reassess diagnosis: rule out SIBO, lactose and fructose malabsorption, IBS, tumors and parasitic infections.

Special situations

Approved in infants for ultrasound preparation. Use «for colic» – at parental request, with a clear conversation about the lack of proven efficacy and the self-limited nature of colic. Safe with any other medications and has no clinically significant drug interactions.

Common myths

Myth: «Espumisan cures gas permanently». Fact: simeticone acts only in the GI lumen and does not address the causes of gas production (diet, SIBO, dysbiosis, enzymopathies).

Myth: «give it to the infant before every feeding». Fact: prophylactic use is not justified, has no proven benefit and reflects only marketing positioning.

Myth: «helps bloating from any cause». Fact: in structural pathology (celiac disease, IBS, tumors) the drug does not target the main mechanism. Symptomatic relief does not replace diagnostic workup.

Drug–drug interactions

2 pairs found. Sorted from critical to minor.

MinorCalcium carbonateMineral supplements. Calcium

Mechanism

Simethicone is a surface-active silicone agent that is not absorbed in the gastrointestinal tract. No direct pharmacokinetic interaction with calcium carbonate.

Symptoms

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

Management

No dose adjustment needed. The combination is standard in symptomatic formulations for bloating and heartburn.

Sources

FDA: Metformin hydrochloride tablet (Sciegen Pharmaceuticals Inc) – Prescribing Information (2017)

Pair details →Calcium carbonate →

MinorMetforminBiguanides. Oral antihyperglycemic agents

Mechanism

Simethicone is a surface-active silicone agent that is not absorbed in the gastrointestinal tract. No direct pharmacokinetic interaction with metformin.

Symptoms

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

Management

No dose adjustment needed. In diabetics with bloating (a metformin side effect), simethicone helps symptomatically. The combination is standard.

Sources

FDA: Metformin hydrochloride tablet (Sciegen Pharmaceuticals Inc) – Prescribing Information (2017)

Pair details →Metformin →

Check interaction with another drug

Opens the checker prefilled with this drug. Pick the second one from your regimen.

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Summary of a multi-drug list →

Medicine list: everything you take in one place →

Frequently asked

What is Simeticone used for?

Simeticone is evaluated for the following indications with varying evidence strength: Preparation for endoscopy or ultrasound (evidence tier B), Functional bloating (evidence tier B), Gastroesophageal reflux disease (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Simeticone?

Common side effects of Simeticone (≥ 1 in 100): Allergic reactions (urticaria, rash). See the Safety section for uncommon and serious reactions.

Is Simeticone safe during pregnancy?

Is Simeticone compatible with breastfeeding?

Not absorbed, does not enter milk in active form. Compatible with breastfeeding.

Who should not take Simeticone?

Simeticone is contraindicated in: Hypersensitivity to simeticone or excipients; Bowel obstruction. Full list in the Safety section.

Espumisan cures gas permanently

simeticone acts only in the GI lumen and does not address the causes of gas production (diet, SIBO, dysbiosis, enzymopathies).

give it to the infant before every feeding

prophylactic use is not justified, has no proven benefit and reflects only marketing positioning.

helps bloating from any cause

in structural pathology (celiac disease, IBS, tumors) the drug does not target the main mechanism. Symptomatic relief does not replace diagnostic workup.

Official sources

Direct links to regulator labels. Open in a new tab.

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