Fibromyalgia ICD-10-CM codes

Fibromyalgia is a single code, M79.7, with no site, laterality or severity axis. It applies to fibromyositis, fibrositis and myofibrositis as well, since those terms all index to M79.7. Widespread muscle pain that the provider has not diagnosed as fibromyalgia is myalgia: M79.10 for an unspecified site, M79.11 for the muscles of mastication, M79.12 for other head and neck muscles, or M79.18 for another site.

Associated conditions are coded separately only when the provider documents them as diagnoses: R53.82 for chronic fatigue, G47.00 for insomnia, F32 or F41 codes for depression or anxiety, and K58 codes for irritable bowel syndrome. Do not add G89.29 (other chronic pain) automatically; assign it when chronic pain is documented and the encounter addresses pain management, and assign G89.4 (chronic pain syndrome) only when that exact diagnosis appears in the record. Pain disorder related to psychological factors (F45.41) is a mental health diagnosis and should not be used as a substitute for M79.7.

Fibromyalgia has no Excludes1 conflict with other rheumatologic diagnoses, so it may be reported together with rheumatoid arthritis, osteoarthritis or lupus when the provider documents both. Long-term duloxetine, pregabalin or other therapy is Z79.899.