Low-dose naltrexone in the treatment of fibromyalgia A systematic review and narrative synthesis

Abstract

Background and objective Fibromyalgia is characterised by chronic, widespread musculoskeletal pain and other systemic symptoms. Current pharmaceutical intervention does not provide consistent pain relief and has detrimental side effects. Clinical experience, case reports, and internet support groups, have increased interest in low-dose naltrexone (1–5 mg) as an off-label treatment for fibromyalgia symptoms. This article summarises the literature around the pathophysiology of fibromyalgia, as well as the evidence on low-dose naltrexone as a potential treatment option. Methods A systematic literature search was conducted using the key words ‘naltrexone’, ‘fibromyalgia’, ‘fibrositis’, ‘chronic pain’ and ‘neurogenic inflammation’. Results Manual exclusion led to the identification of 21 papers, with only five prospective controlled trials of low sample size. Discussion Low-dose naltrexone may be an effective and safe pharmacotherapy for patients with fibromyalgia. Current evidence lacks power and multisite reproduction