Efficacy of Low-Dose Naltrexone in Treating Patients with Fibromyalgia: systematic Review and Meta-Analysis

Low-dose naltrexone (LDN) has demonstrated mixed efficacy in treating fibromyalgia. This systematic review and meta-analysis aimed to evaluate the efficacy of LDN for fibromyalgia. We systematically searched electronic databases and gray literature from inception to May 2024. Included studies were clinical trials in humans published in English, reporting mean changes in pain scores and fibromyalgia symptom severity, comparing baseline to endpoint and LDN to placebo. Of 575 identified articles, eight met the eligibility criteria. In the LDN group, the Standardized Mean Difference (SMD) for pain decreased by 1.03 (95% confidence interval (CI): −1.25, −0.80; I² = 25%), and fibromyalgia symptom severity decreased by 1.02 (95% CI: −1.35, −0.69; I² = 52%) post-LDN treatment compared to the baseline. However, no significant differences in mean change in pain (SMD −0.50, 95% CI: −1.19, 0.19; I² = 91%) and fibromyalgia symptoms severity scores (SMD −0.67, 95% CI: −1.67, 0.34; I² = 95%) were observed between the LDN and placebo groups. Although LDN marginally reduced pain and symptom severity from baseline, these effects were not superior to placebo. This suggests that LDN may not provide significant clinical benefit over placebo in fibromyalgia management, warranting further research.