Clinical Overview of Fibromyalgia.McCarberg BH. Am J Ther. 2011 Feb 15. [Epub ahead of print] Fibromyalgia (FM) is a complex disorder that affects up to 5% of the general population worldwide, more frequently in women than in men. In addition to chronic widespread pain, patients with FM usually experience other characteristic symptoms, including fatigue, disturbed sleep, stiffness, reduced functioning, dyscognition, and depressed mood. Many patients also have comorbid conditions such as depression, irritable bowel syndrome, temporomandibular disorder, or migraine. Although the etiology of FM remains unclear, evidence suggests that biologic, genetic, and environmental factors are involved. The variability of symptoms and the frequency of comorbidities among patients with FM make this a difficult disorder to diagnose. Diagnosis may be further complicated by the stigmatization of this disorder among treatment providers, the health insurance industry, and the general population. Treating chronic pain disorders such as FM can be time consuming and costly, and other issues such as polypharmacy, treatment adherence, and access to treatment often need to be addressed. The aim of this article is to provide physicians with a general overview of FM, including a brief review of the pathophysiology that explains the biologic and genetic bases of this disorder. Also included is a synopsis of new diagnostic criteria and other useful diagnostic tools and a discussion of various treatment challenges and strategies.