The study has a double purpose: a first phase intends to assess the effectiveness and tolerability of trazodone, an antidepressant with sedative and sleep-promoting properties, in the treatment of fibromyalgia; a second phase intends to evaluate if the addition of pregabalin to patients who have shown a partial response to trazodone additionally improves fibromyalgia symptomatology.

Inclusion Criteria:

• patients diagnosed of fibromyalgia according to the American College of Rheumatology criteria
• written, informed consent
• able to understand and comply with the requirements of the study

Exclusion Criteria:

• pregnancy or breastfeeding
• unwillingness to discontinue other prescribed medications before entering in the study
• patients who had previously received trazodone without improvement or who did not tolerate the drug
• patients who had previously received pregabalin without improvement or who did not tolerate the drug (only for the phase II of the study)