This is a multi-center, randomized, double-blinded placebo controlled trial to evaluate the efficacy and safety of the substance-based medical device (Sollievo Fisiolax) in the treatment of Chronic Constipation.

Treatment period for each patient is 28 days.

According to the criteria of Rome IV, 86 patients diagnosed from chronic constipation will be enrolled by up to ten centers.

The study includes 2 visits at the site center and 1 by phone call.

V-1 (eligibility assessment / screening visit):

• Collection of written informed consent
• Physical examination, including measurement of anthropometric parameters and vital signs (height, weight, diastolic / systolic pressure, heart rate)
• Diagnosis according to Rome IV criteria of chronic functional constipation
• Blood tests: glycemia, creatinine, complete blood count with formula, ALT, AST, ALP, calcium, potassium, sodium, C reactive protein, total bilirubin. Urinalysis.
• Performing a colonoscopy for patients aged> 50 who have not had one performed in the last 5 years.
• Guideline for daily diary to collect the number and the consistency of the evacuations, and whether or not they occur with effort
• Recording of adverse events and concomitant therapies

V0 (confirmation of possession of selection criteria):

• Physical examination, including measurement of anthropometric parameters and vital signs (height, weight, diastolic / systolic pressure, heart rate)
• Randomization 1:1 to Sollievo Fisiolax or Placebo
• Blood and fecal sample collection for the evaluations of the exploratory objectives
• Compliance of the daily diary
• Administration of questionnaires: Gastrointestinal Quality of Life Index (GIQLI), PAC-SYM
• Any changes in concomitant therapies and any adverse events will be recorded.

V1 (end of treatment or discontinuation before study / treatment time; 4 weeks after V0):

• Physical examination, including measurement of anthropometric parameters and vital signs (height, weight, diastolic / systolic pressure, heart rate)
• Returned the Investigational product
• Blood and fecal sample collection for the evaluations of the exploratory objectives.
• Blood tests: glycemia, creatinine, complete blood count with formula, ALT, AST, ALP, calcium, potassium, sodium, C reactive protein, total bilirubin. Urinalysis.
• Blood sampling for the screening of HIV, HCV, HBV and TPHA
• Check of daily diary
• Administration of questionnaires: Gastrointestinal Quality of Life Index (GIQLI), PAC-SYM
• Any changes in concomitant therapies and any adverse events will be recorded

Inclusion Criteria:

1. Patient giving written informed consent to participate in the study.
2. Patient of both sexes aged between 18 and 70 years (inclusive)
3. Patient affected by chronic functional constipation according to the Rome IV criteria
4. In patients over the age of 50, negative colonoscopy, i.e. absence of clinically relevant alterations or in any case of critical condition for study participation, performed during the run-in period unless:

at least negative colonoscopy performed in the previous 5 years the symptoms have remained unchanged, if present, from the time of the execution of the (or last, if more than one) colonoscopy

Exclusion Criteria:

1. Hypersensitivity or Suspected or known allergy to one of the components of the products under study

2. Have previously taken the study product

3. Therapy with antibiotics within 4 weeks prior to the screening visit (i.e, prior to the visit V -1)

4. Therapy within 2 weeks of the run-in (i.e., prior to the visit V0) with: Laxatives / fecal softeners / intestinal bulking products; Drugs indicated for the treatment of obesity; probiotics or prebiotics

5. Chronic inflammatory bowel diseases

6. Intestinal diseases of infectious, actinic, endocrine or pharmacologic origin (microscopic colitis)

7. Patients undergoing gastro-intestinal resection

8. Renal, hepatic, haematological, cardiovascular, pulmonary, neurological, psychiatric, immunological, endocrine diseases, if they are clinically significant

9. Patients with malignant neoplasm of any type, or history of malignancy, with the exclusion of patients with a history of extra-intestinal malignant neoplasm surgically removed and no evidence of recurrence within the five years prior to participation

10. Abuse of alcohol, narcotics or psychotropic drugs that can change vigilance and physical perception

11. Presence of a dementia of any type or other possible causes of progressive deterioration of the capacity to understand and of want or psycho-physical disability that reduces the ability to assume as expected the study treatment

12. Obesity (BMI ≥ 30)

13. No adequate reliability or conditions that may lead to a non-compliance / adherence of the patient to the protocol

14. Previous participation in a clinical trial in the last 30 days

15. Patients who for any reason do not agree to guarantee the commitment to keep their diet stable for the study period

    • During the run-in period, in case of severe symptoms, the use of an evacuant to be applied rectally, indicated in constipation and identified by the Investigator, can be used as a "rescue" therapy.