Iberogast (STW-5)
A fixed nine-herb liquid built around bitter candytuft, peppermint and chamomile, used for functional dyspepsia. Several placebo-controlled trials favour it, though the most recent Cochrane assessment rates the certainty of that evidence as low.
Evidence last reviewed: August 2026
What the science says
- Functional dyspepsia symptoms Moderate evidence
A meta-analysis pooling raw data from three placebo-controlled trials (273 patients) found STW 5 clearly better than placebo for the most bothersome gastrointestinal symptom (odds ratio 0.22). A 2023 Cochrane review of 41 herbal-medicine trials agreed that STW 5 may moderately improve global dyspepsia symptoms but graded the certainty as very low because of heterogeneity.
- Comparison with prokinetic drugs Limited evidence
One reference-controlled trial found no significant difference between STW 5 and cisapride, but an equivalence finding in a single trial without a placebo arm is weak evidence of real efficacy.
- Irritable bowel syndrome Limited evidence
STW 5 is also marketed for IBS, but the controlled data there are older and sparser than the dyspepsia trials, and no high-certainty synthesis supports it.
Dosage & safety
Scientific references
Where to buy
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