The present randomized, controlled double blind trial aims to evaluate the efficacy and tolerability of balneotherapy with mineral water named "Debole of Vetriolo" in 100 patients with primary Fibromyalgia Syndrome (FS).

The fibromyalgia syndrome (FS) is a chronic condition that is characterized by chronic widespread pain, fatigue, sleep disorders, cognitive disturbances, physical and psychological distress. It was estimated that between 2.9 and 3.8% of the general population in Europe and the US are affected , with the majority of patients in clinical settings being female . Clinical research suggests that pharmacologic treatment alone is not the best approach for FS, and that an integrated approach that includes non-pharmacologic therapies along with pharmacologic therapies improves outcomes in these patients.

Balneotherapy is one of the most commonly used non-pharmacological approaches for SF, but it is still being discussed and its role in modern medicine is still not clear. The action mechanisms of thermal baths are not completely known, and it is difficult to distinguish the effects of thermal applications from the benefits that could be derived from a stay in a spa environment.

The present randomized, controlled double blind trial aims to evaluate the efficacy and tolerability of balneotherapy with mineral water named "Debole of Vetriolo" in patients with primary SF fulfilling the 2010 ACR criteria.

Following confirmation that the patients fulfill the screening criteria and having obtained written informed consent, 100 patients will be randomized 1:1 and allocated to one of two groups using a computer-generated table of random numbers:

Group I (50 patients) will be treated with daily thermal-mineral bath with mineral water named "Debole of Vetriolo" for a total of 12 applications carried out over a period of two weeks at Levico Terme Spa Center (Levico Terme, Italy)

Group II (50 patients), the control group, will be treated with daily thermal bath with with tap water bath for a total of 12 applications carried out over a period of two weeks at Levico Terme Spa Center (Levico Terme, Italy)

The block randomization list will be kept by individuals who have no contact with the investigators who assign patients to their randomized treatment, and who will not perform any patient assessment or conduct the statistical.

All patients will undergo general medical evaluation and rheumatologic examination by the same physician before the start of the study. All the demographic, anamnestic and clinical data will be collected on identical questionnaires. Each patient will be assessed at baseline time (T0), after 2 weeks (T1),after 3 months (T2), 6 months (T3), following the beginning of the study.

All assessments will be performed at Levico Terme Spa Centre by the same rheumatologist who will be blinded to which study arms the patients belongs. Laboratory analysis will be performed only at baseline.

Assessments at each examination will include:

Primary Outcome Measures

• Visual Analogue Scale (VAS);
• Fibromyalgia Impact Questionnaire total score (FIQ-Total) e Fibromyalgia Impact Questionnaire Physical score (FIQ-PI)

Secondary Outcome Measures

• Widespread Pain Index (WPI)
• Symptom Severity (SS)
• Short Form Health Survey (SF-12)
• State-Trait Anxiety Inventory (STAI)
• Center for Epidemiologic Studies Depression Scale (CES-D)

Inclusion Criteria:

• Patients suffering from FS according to American College of Rheumatology (ACR) criteria for at least 3 months and with a stable treatment for at least 4 weeks
• Have a score of WPI≥7 and SS ≥ 5 or WPI 3-6 and SS≥9 screening and baseline visit
• Provide written informed consent to participate in the study

Exclusion Criteria:• Concurrent participation in other therapeutic trials

• Patients that have been treated with mud-pack therapy and/or balneotherapy in the last 6 months
• Patients affected by neoplastic diseases in the last five years, with cardiovascular disease of recent onset, suffering from serious impairment of hematopoietic, renal and hepatic systems
• Presence of concurrent autoimmune or inflammatory disease, such as, rheumatoid arthritis, systemic lupus erythematous, inflammatory bowel disease, etc.
• Pregnant and nursing mothers
• Severe psychiatric illnesses (current schizophrenia, major depression with suicidal ideation, within two years)
• Routine daily use of narcotic analgesics or history of substance abuse
• Patients unable to complete the questionnaires