The study shall prove whether treatment of irritable bowel syndrome with Iberogast is superior to placebo regarding the main criterium "pain"

Inclusion Criteria:

• Patients of either sex aged >18 years

• Patients meeting the Rome III irritable bowel syndrome (IBS) diagnostic criteria. IBS is defined as recurrent abdominal pain or discomfort at least 3 days/month in last 3 months (onset at least 6 months ago) associated with two or more of the following:

  • Improvement with defecation
  • Onset associated with a change in frequency of stool
  • Onset associated with a change in form (appearance) of stool

• History of pain intensity with an average of worst abdominal pain in past 24 hours score of > 30 on a daily measured VAS (visual analogue scale) during screening phase

Exclusion Criteria:

• Intake of STW5 within the last 5 years
• Concomitant treatment during the study (including screening phase) with any medication that could influence the gastrointestinal function
• Regular intake of nonsteroidal antiphlogistic drugs incl. COX-2-inhibitors (exception: acetylsalicylic acid for cardiovascular prevention up to 100 mg daily)
• Patients with known hypersensitivity to any component of the trial drugs
• History of eating disorders
• Patients with a history of diseases with abdominal symptoms that can resemble IBS
• Presence of any other acute or chronic gastrointestinal disorder
• History of abdominal surgery (cholecystectomy and appendectomy can be tolerated when performed at least one year previously)
• Known intolerance to azo dyes E 110 and E 151