The purpose of this study is to examine the characteristics of the nerves and the small veins in the skin of people with fibromyalgia. The investigators will then use this information to identify possible processes in the skin that may help explain why some people feel pain relief with the study drug (duloxetine) and others do not.

Duloxetine affects certain chemicals in the brain called neurotransmitters. An abnormality in these chemicals is thought to be related to fibromyalgia. Duloxetine is a selective serotonin and norepinephrine reuptake inhibitor (SNRI), similar to some drugs used for the treatment of depression. Duloxetine is approved for sale in the United States by the Food and Drug Administration (FDA) for the treatment of fibromyalgia.

Inclusion Criteria:

• Female age 18-70
• Fulfill the ACR criteria for FMS (wide spread pain for at least 3 months and pain in at least 11 of 18 tender point sites.
• VAS score greater than 40mm at Screening and Randomization Visits

Exclusion Criteria:

• History of clinically significant liver disease, serious peripheral vascular disease, a blood clotting disorder, or any other medical condition felt to be exclusionary by the investigator
• Allergy to lidocaine
• Unwillingness to sign informed consent or any other reasons for which the investigator feels the subject cannot complete the study.
• Women who are pregnant, breastfeeding or trying to become pregnant
• Active cancer within the previous two years except treated basal cell carcinoma of the skin
• Presence of dermatological or neurological condition that could interfere with the interpretation of the skin biopsy or QST
• Co-existing conditions that can produce chronic widespread pain
• Presence of uncontrolled or severe depression
• Patients with pending Worker's Compensation, worker's Compensation, any ongoing litigation or disability claims due to fibromyalgia or any other source of pain, or currently receiving monetary compensation as a result of any of the above.
• Presence of uncontrolled narrow-angle glaucoma