This study is aimed to investigate the efficacy and safety of Colilen IBS, a Medical Device made of natural substances, even when taken in addition to other therapies, for the treatment of Irritable Bowel Syndrome.

This is a Post Market, randomized, double blind, cross-over clinical evaluation that will be conducted in 66 patients with diagnosis of Irritable Bowel Syndrome according to Rome IV criteria. As this is a cross-over clinical investigation, each eligible patient will take both the products under investigation, Colilen IBS and its Placebo.

After a 2-week run-in period, at Baseline visit each patient included in the study will be randomly assigned to one of the two treatment sequences (i.e., Sequence AB and Sequence BA), for a 16-week total sequential treatment period (8 weeks for each of the 2 treatment periods) first with verum Colilen IBS and then with its Placebo, or vice versa. A wash out period (3 weeks) is forecast between the two treatment periods.

Inclusion Criteria:

• 1. Male or female patients aged 18 to 75 years (inclusive);

• 2. Diagnosis of IBS according to ROME IV criteria (Appendix 3);

• 3. Abdominal pain score ≥ 4 on a 11-point NRS, on at least 2 days of the 14 days prior to the baseline visit and on at least 2 days of the last 14 days of the washout period, and pain score not > 8 in more than 7 days of each of the two above-mentioned periods;

• 4. Signed Informed Consent;

• 5. Patients' ability to comply with the study procedures;

• 6. Stable diet in the two months prior to the screening visit;

• 7. *Negative colonoscopy, defined as the absence of clinically relevant changes or of changes nonetheless relevant in relation to study participation risk, performed during the run-in period, unless:

  • a colonoscopy was performed within the previous 5 years and was negative as intended above, or, if more than one was performed within the previous 5 years, the last being negative as intended above;
  • the symptoms, if any, for which the last colonoscopy was performed, have remained unchanged;

• 8. Postmenopausal female patients, i.e., females who have not had a menstrual period for at least 12 months or women who have undergone surgical sterilisation (tubal ligation or ovary removal). If not, women of childbearing potential must follow reliable contraceptive treatment.

  • Inclusion criteria applicable only for patients > 50 years of age

Exclusion Criteria:

• 1. Patients taking treatments that may significantly affect the efficacy outcomes measures, such as: probiotics and prebiotics (unless contained in milk-derived foods such as yogurt and cheese); drugs with adsorbent/sequestrant properties such as diosmectite; 5-HT3 receptor antagonist drugs, e.g. ondasetron; drugs that modify gastro-intestinal motility, e.g. "final" anti-cholinergic agents such as loperamide, or cholinergic agents; laxatives and faecal softeners) unless they have been taken at a stable dose for at least four weeks prior to the screening visit.
• 2. Patients taking tricyclic antidepressants within six months prior to the screening visit;
• 3. Patients taking opioid-containing analgesics within one month prior to the screening visit;
• 4. Patients taking antibiotics within one month prior to the screening visit;
• 5. Patients with relevant organic, systemic or metabolic disease, or laboratory changes, that are deemed significant based on specific ranges of normality;
• 6. Patients with organic bowel diseases;
• 7. Patients with unstable psychiatric conditions;
• 8. Patients who have undergone major abdominal surgery, except appendectomy;
• 9. Known hypersensitivity to one or more of the components of the products.
• 10.Women with known or planned pregnancy or breastfeeding;
• 11.Patients with malignancies of any type, or with a history of prior malignancies, except for patients with a history of extra-intestinal malignancies that have been surgically removed and have not relapsed within the five years prior to participation.