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Moderate evidenceGut health

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.

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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

Studied dose20 drops three times daily, taken before or with meals, for 4–8 weeks in the trials.
SafetyAdverse events in trials were similar to placebo. Rare cases of liver injury have been reported and led to a labelling change; the formula contains a substantial amount of ethanol, which matters for children, pregnancy and people avoiding alcohol. Greater celandine, previously in the formula, was the suspected hepatotoxic component and has been removed from reformulated versions.

How to take it

Timing20 drops three times a day, before or with meals.
With food?Before or with meals, stirred into a little water or juice.
Worth knowingStop it and get liver enzymes checked if you develop dark urine, yellowing eyes or persistent nausea.

Interactions

With medications

  • disulfiram and metronidazole

    The liquid contains a substantial amount of ethanol, which can cause a flushing reaction with these drugs. avoid the alcohol-containing formulation

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does Iberogast work for functional dyspepsia?

Iberogast (STW 5) has moderate evidence: pooled data from three placebo-controlled trials in 273 patients favoured it clearly over placebo. A 2023 Cochrane review agreed it may moderately improve dyspepsia symptoms but graded the certainty as very low.

How do I take Iberogast?

The trials used 20 drops of Iberogast three times a day, before or with meals, stirred into a little water or juice, for 4–8 weeks.

Is Iberogast safe for the liver?

Rare cases of liver injury with Iberogast led to a labelling change; greater celandine, the suspected component, has been removed from reformulated versions. Stop and get liver enzymes checked if you develop dark urine, yellowing eyes or persistent nausea.

Does Iberogast contain alcohol?

Yes. Iberogast contains a substantial amount of ethanol, which matters for children, pregnancy and people avoiding alcohol, and it can cause a flushing reaction with disulfiram or metronidazole.

Scientific references

Related in Gut health

Herbal medicines: what the evidence says (335)