Iberogast Review (2026): Does STW 5 Work for Indigestion?

Iberogast occupies an odd position. It is a herbal liquid sold next to the peppermint capsules and digestive enzymes, which is exactly where products with no trial evidence usually live — and yet it has been through placebo-controlled randomized trials and a head-to-head against a prescription drug, which almost nothing else on that shelf has. It also carries a genuine liver-safety history that its marketing does not lead with. This review separates those three things: what the trials found, what the safety record shows, and which of the two different formulations you are actually buying.

This article is for general education and isn't a substitute for care from your own physician or gastroenterologist.

What Iberogast Is, and Which Version You're Buying

Iberogast is the brand name for STW 5, a fixed combination of herbal extracts taken as drops in water before or with meals. The original formulation contains nine extracts, built around bitter candytuft (Iberis amara) and including peppermint leaf, chamomile flower, caraway fruit, lemon balm, licorice root, angelica root, milk thistle fruit, and greater celandine (Chelidonium majus).

That last ingredient is why there are two products. Following a long dispute with German regulators over liver-injury reports, the manufacturer both added liver warnings to the leaflet and brought a reformulated six-herb version to market, which omits greater celandine along with angelica root and milk thistle. In the research literature this refined version is called STW 5-II; on shelves it has appeared under names such as Iberogast Advance.

This matters for anyone reading the evidence, because the two versions are not interchangeable in the trials. It also matters for anyone buying in the US: the Amazon listing for Iberogast liquid drops describes the product as a six-herb blend with Iberis amara, peppermint, and licorice — that is, the reformulated version, not the nine-herb original that most of the liver-injury case reports concern. Formulations and labels change, so the practical advice is to read the ingredient list on the bottle in front of you and look specifically for greater celandine or Chelidonium majus.

Mechanistically, the pitch is that a multi-herb preparation hits several targets at once — motility, visceral sensitivity, inflammation, and mucosal barrier function — rather than one. A narrative review of the preparation frames it in exactly those terms PMID: 41319263. Worth noting when reading that review: one of its listed authors is affiliated with a medical communications company, and the literature on this product is unusually sponsor-adjacent throughout.

The Evidence: What the Trials Actually Show

The meta-analysis. Researchers identified six randomized controlled trials using STW 5, then reanalysed and pooled the raw data from the three placebo-controlled studies that met their selection criteria. Pooled, the herbal preparation (n = 138) beat placebo (n = 135) for the severity of the most bothersome gastrointestinal symptom, with an odds ratio of 0.22 (95% CI 0.11-0.47, p = 0.001). Adverse events were similar to placebo and no serious adverse events occurred in the analysed trials PMID: 15606389. That is a clear result — from a total of 273 patients, in an analysis whose authors state they consulted the producer during the search.

The head-to-head against a real drug. This is the most interesting trial in the file. 186 patients with dysmotility-type functional dyspepsia were randomized in a double-blind, double-dummy design to one of three arms: STW 5, the six-herb STW 5-II, or cisapride, a prescription prokinetic. Over four weeks, non-inferiority was established for both herbal preparations against the drug, with no significant differences in secondary endpoints PMID: 12055663. Two caveats belong with it: a non-inferiority finding against an active comparator is weaker evidence than superiority over placebo, and cisapride was subsequently withdrawn from the US market over cardiac arrhythmias — so "as good as cisapride" is a benchmark that no longer exists in American pharmacies. What it does establish is that the six-herb version, the one sold in the US, was studied alongside the original rather than being an untested substitute.

The newest trial, and its mixed result. A 2025 randomized, double-blind, placebo-controlled study put 32 functional dyspepsia patients with bloating through a gastric gas challenge after two weeks on STW 5-II or placebo. Early gas evacuation was significantly faster on the herbal preparation (319 ± 81 mL versus 80 ± 39 mL, p = 0.015), and symptom perception during the challenge was significantly lower (score increment 0.8 ± 0.4 versus 2.1 ± 0.4, p = 0.036). But the difference in gas evacuation did not hold across the full 90 minutes (final retention p = 0.431), and there was no significant difference in measured abdominal distension PMID: 40684457. It is a small mechanistic study with a genuinely mixed result, and it deserves to be read that way rather than as a symptom-relief trial.

How it doesn't work. A placebo-controlled study in patients with functional dyspepsia and gastroparesis found that STW 5's clinical effects are not based on accelerating gastric emptying — the stomach did not empty faster PMID: 19220753. That is a useful negative finding, because "it speeds up digestion" is a common informal explanation for why the product might help, and the measurement doesn't support it.

Beyond dyspepsia. A randomized, double-blind, placebo-controlled trial tested Iberogast on tolerance to colonic gas in irritable bowel syndrome patients PMID: 38361151, and an older clinical-evidence review summarises the wider trial programme PMID: 16978851. The IBS evidence is thinner than the dyspepsia evidence, and if IBS is your actual diagnosis, the options in our IBS treatments that work guide have more directly applicable data.

What the guidelines say. Nothing, essentially. The joint American College of Gastroenterology and Canadian Association of Gastroenterology guideline on dyspepsia does not include Iberogast among its recommended therapies PMID: 28631728. Absence from a guideline is not evidence of harm, but for a product with published positive trials it is a fair signal of how the wider field weighs trials that are old, small, and sponsor-linked.

The Liver-Injury Story

This section exists because the marketing does not cover it and it is the single most important safety fact about the product's history.

Serious liver injury has been attributed to Iberogast in the case-report literature, including a case of severe hepatotoxicity that led to liver transplantation PMID: 27580789 and a more recent case report of acute liver injury PMID: 39132058. The ingredient the signal points at is greater celandine, which has an independent literature of herb-induced liver injury: a review of the published cases PMID: 28379595, a 2024 report of two further cases with a literature review PMID: 38820341, and another documented case of jaundice attributed to the plant PMID: 38682076.

Three things keep this in proportion. These reactions are rare relative to very wide use over five decades. The efficacy trials recorded adverse events at rates similar to placebo, with no serious events PMID: 15606389. And the reformulated six-herb version — which the current US Amazon listing describes — omits greater celandine altogether, which removes the ingredient the case reports implicate.

What that adds up to in practice: check the label for greater celandine or Chelidonium majus. If you have liver disease, drink heavily, or take medication with known liver effects, talk to a clinician before starting any multi-herb preparation. And stop and seek medical advice if you develop jaundice, dark urine, persistent nausea, or right-upper-abdominal pain while taking it.

How It Compares to the Alternatives

Against omeprazole-class acid suppressants, Iberogast has less and older evidence: a Cochrane review of 25 randomized trials in 8,453 people supports PPIs for dyspepsia symptoms with a number needed to treat of 11 PMID: 29161458. The two have never been compared directly. The sensible way to choose is by dominant symptom — burning epigastric pain points toward acid suppression, meal-related fullness points toward this kind of multi-target preparation.

Against a peppermint-and-caraway oil combination, the comparison is closer. That fixed combination beat placebo for pain and discomfort in a 114-patient functional dyspepsia trial PMID: 28695660. Its practical problem in the US is availability of the studied combination product.

And before either: if you have not been tested for Helicobacter pylori, that comes first. Eradication therapy in H. pylori-positive patients with functional dyspepsia improved symptoms with a number needed to treat of 9, dropping to 4.5 where eradication succeeded, on high-quality evidence PMID: 35022266. No supplement in this category comes close to those numbers, and it is a time-limited treatment rather than an indefinite one. Our functional dyspepsia guide walks through the full sequence.

Price, Dosing, and Practicalities

Iberogast runs roughly $28 for a 50 mL bottle at typical Amazon pricing, which works out to about a month at the standard labeled dose taken three times daily with meals. That is in line with a mid-priced supplement and cheaper than most premium probiotics, though more expensive than OTC omeprazole.

The format is liquid drops added to a small amount of water, which some people dislike — the taste is strongly herbal and bitter by design, since bitter compounds are part of the proposed mechanism. There is no capsule version of the studied preparation.

Give it four weeks, the duration used in the supportive trials, before judging it. Track symptoms deliberately: a simple daily note on fullness, early satiety, and upper-abdominal pain beats trying to remember how last month felt.

Who It Suits, and Who Should Skip It

It is a reasonable option if your dominant complaint is meal-related upper-abdominal fullness or early satiety, you have already been tested for H. pylori, and you would rather try something with published placebo-controlled trials than a supplement with none. It is also a defensible choice for someone who has tried acid suppression without much benefit, since it acts on different targets.

Skip it, or talk to a clinician first, if you have liver disease or take hepatotoxic medication; if you are pregnant or breastfeeding; if your symptoms include alarm features such as weight loss, difficulty swallowing, vomiting, or signs of bleeding, which need assessment rather than a herbal trial; or if your main symptom is actually heartburn rising into the chest, in which case our acid reflux and GERD guide is the better starting point. If lower-abdominal gas and bloating dominate, compare the options in our bloating supplement rankings instead.

Our Verdict

Rating: 3.8/5.

Iberogast earns a genuinely higher score than most herbal digestive products for one reason: it has been tested. A pooled reanalysis of three placebo-controlled trials favoured it over placebo, and a double-blind, double-dummy trial found both the original and the six-herb version non-inferior to a prescription prokinetic. Almost nothing else sold in the same aisle can point to either. The reformulated version now sold in the US also drops the ingredient behind the product's liver-injury reports, which is a real improvement rather than a cosmetic one, and that version was included in the cisapride comparison rather than reaching the market untested.

What keeps it from a higher score is the age and independence of the evidence. The two pivotal studies are from 2002 and 2004, enrolled a few hundred patients between them, and were run with manufacturer involvement; the most recent trial is a 32-person mechanistic study with a mixed result; the literature around the product is heavily sponsor-adjacent; and major treatment guidelines do not list it. It also has no head-to-head data against the drugs most people will actually be offered.

Where it lands: a defensible second step for meal-related indigestion after H. pylori testing, with better evidence than the supplements beside it and weaker evidence than the tablets behind the pharmacy counter. If you want the full treatment sequence rather than a single product, start with our functional dyspepsia guide.

Frequently Asked Questions

Does Iberogast actually work, or is it just an expensive herbal blend? It has real placebo-controlled evidence, which is unusual here. A meta-analysis of pooled raw data from three placebo-controlled trials found it more effective than placebo (odds ratio 0.22), and a randomized trial in 186 patients found it non-inferior to the prescription prokinetic cisapride. The qualification: those trials are from 2002-2004, small, and manufacturer-involved.

Why does Iberogast have nine herbs in some countries and six in others? Because of a liver-safety dispute. The original nine-herb formulation contained greater celandine, linked to rare drug-induced liver injury. After regulatory pressure in Germany the manufacturer added liver warnings and also markets a six-herb reformulation that omits greater celandine, angelica root, and milk thistle. The current US Amazon listing describes a six-herb blend.

Is Iberogast safe for the liver? The concern is specifically greater celandine. Case reports document serious liver injury attributed to Iberogast, including one requiring transplantation, and greater celandine has its own herb-induced liver injury literature. The six-herb version omits that ingredient. Check the label, and check with a clinician if you have liver disease.

What is Iberogast supposed to treat? Its trial evidence is in functional dyspepsia — upper-abdominal fullness, early satiety, and epigastric pain with no structural cause. It is marketed more broadly, and has a small IBS trial, but functional dyspepsia is where the evidence sits.

How long does Iberogast take to work? The supportive trials ran four weeks, so that's a fair minimum before judging it, taken consistently at the labeled dose.

Is Iberogast better than a proton pump inhibitor for indigestion? They have never been compared directly. PPIs have the larger and more recent evidence base; Iberogast's trials targeted meal-related symptoms. Choose by dominant symptom rather than by evidence volume alone.

References

1. Melzer J, Rösch W, Reichling J, et al. Meta-analysis: phytotherapy of functional dyspepsia with the herbal drug preparation STW 5 (Iberogast). Alimentary Pharmacology & Therapeutics. 2004;20(11-12):1279-1287. PMID: 15606389.
2. Rösch W, Vinson B, Sassin I. A randomised clinical trial comparing the efficacy of a herbal preparation STW 5 with the prokinetic drug cisapride in patients with dysmotility type of functional dyspepsia. Zeitschrift für Gastroenterologie. 2002;40(6):401-408. PMID: 12055663.
3. Aguilar A, Alcala-Gonzalez L, Barber C, et al. Effect of STW 5-II (Iberogast-N) on tolerance to gastric gas in patients with functional dyspepsia. The IBO-2 study. Neurogastroenterology & Motility. 2025;37(11):e70123. PMID: 40684457.
4. Braden B, Caspary W, Börner N, et al. Clinical effects of STW 5 (Iberogast) are not based on acceleration of gastric emptying in patients with functional dyspepsia and gastroparesis. Neurogastroenterology & Motility. 2009;21(6):632-638. PMID: 19220753.
5. Rösch W, Liebregts T, Gundermann KJ, et al. Phytotherapy for functional dyspepsia: a review of the clinical evidence for the herbal preparation STW 5. Phytomedicine. 2006;13 Suppl 5:114-121. PMID: 16978851.
6. Lambiase C, Usai Satta P, Bassotti G, et al. Iberogast in functional dyspepsia: yesterday, today, and tomorrow — a narrative review of a multitarget phytomedicine. Expert Opinion on Pharmacotherapy. 2025;26(17):1867-1876. PMID: 41319263.
7. Aguilar A, Benslaiman B, Serra J. Effect of Iberogast (STW5) on tolerance to colonic gas in patients with irritable bowel syndrome: a randomized, double-blind, placebo control clinical trial. Neurogastroenterology & Motility. 2024;36(10):e14765. PMID: 38361151.
8. Moayyedi P, Lacy BE, Andrews CN, et al. ACG and CAG clinical guideline: management of dyspepsia. The American Journal of Gastroenterology. 2017;112(7):988-1013. PMID: 28631728.
9. Sáez-González E, Conde I, Díaz-Jaime FC, et al. Iberogast-induced severe hepatotoxicity leading to liver transplantation. The American Journal of Gastroenterology. 2016;111(9):1364-1365. PMID: 27580789.
10. Leroy A, Perrin H, Porret R, et al. Iberogast-induced acute liver injury — a case report. Gastro Hep Advances. 2022;1(4):601-603. PMID: 39132058.
11. Pantano F, Mannocchi G, Marinelli E, et al. Hepatotoxicity induced by greater celandine (Chelidonium majus L.): a review of the literature. European Review for Medical and Pharmacological Sciences. 2017;21(1 Suppl):46-52. PMID: 28379595.
12. Ciornolutchii V, Ismaiel A, Sabo CM, et al. A hidden cause of hypertransaminasemia: liver toxicity caused by Chelidonium majus L. Report of two cases of herb-induced liver injury and literature review. American Journal of Therapeutics. 2024;31(4):e382-e387. PMID: 38820341.
13. Power S, Barritt AS. A yellow flower with jaundice power: liver injury attributed to greater celandine. ACG Case Reports Journal. 2024;11(5):e01347. PMID: 38682076.
14. Pinto-Sanchez MI, Yuan Y, Hassan A, et al. Proton pump inhibitors for functional dyspepsia. Cochrane Database of Systematic Reviews. 2017;11:CD011194. PMID: 29161458.
15. Rich G, Shah A, Koloski N, et al. A randomized placebo-controlled trial on the effects of Menthacarin, a proprietary peppermint- and caraway-oil-preparation, on symptoms and quality of life in patients with functional dyspepsia. Neurogastroenterology & Motility. 2017;29(11). PMID: 28695660.
16. Ford AC, Tsipotis E, Yuan Y, et al. Efficacy of Helicobacter pylori eradication therapy for functional dyspepsia: updated systematic review and meta-analysis. Gut. 2022. PMID: 35022266.