Pain is one of the main factors assessed in most of the scores used to measure activity in rheumatoid arthritis (RA) and spondylo arthritis (SpA). However, the experience of pain is complex, subjective and influenced by many factors. Fibromyalgia (FM) is present in 16-38% of patients with inflammatory rheumatic diseases (IRD) and has been shown to significantly increase indices of disease activity, often preventing an adequate response to immunosuppressive treatments. Recognition of secondary FM is important to avoid overtreatment. This article explores the relationship between FM and IRD, and how to optimise the assessment and treatment of one in the presence of the other.