Evaluation of Low-Dose Naltrexone for Chronic Pain Management

Naltrexone is an opioid antagonist approved by the Food and Drug Administration (FDA) for alcohol use disorder and opioid use disorder. More recently, naltrexone has been used off-label at low doses of 4.5 mg daily for chronic pain due to fibromyalgia, neuropathy, complex regional pain syndrome, and multiple sclerosis. While several studies show the promise of low-dose naltrexone in treating chronic pain, most had small sample sizes and short-term follow up, which warrants additional investigation into the effectiveness of low-dose naltrexone. This medication use evaluation aimed to evaluate the effectiveness of low-dose naltrexone for chronic pain in Veterans through retrospective chart review. The average duration of low-dose naltrexone therapy was 123 days with approximately half of Veterans still taking it at the time of chart review. The average change in pain score from initiation to most recent visit was -0.83. Low-dose naltrexone was generally well-tolerated with 32% (13 of 41) of Veterans reporting adverse effects including vivid dreams, drowsiness, dizziness, and nausea. Low-dose naltrexone resulted in a small decrease in pain, although may be considered after a patient has failed multiple lines of therapy for additional pain control after a risk versus benefits discussion.