Low Dose Naltrexone for the Treatment of Fibromyalgia

Fibromyalgia is a significant problem in the United States, afflicting millions of people with chronic, widespread muscle pain that can be severe and debilitating. In addition to pain, fibromyalgia is associated with fatigue, difficulty sleeping, headache, and stomach problems. These symptoms often interfere with the activities of daily living to the point where they prevent sufferers from functioning normally. Although no one knows why, women are more likely than men to suffer from fibromyalgia.

The FDA has currently approved three medications for the treatment of fibromyalgia, but they don’t work well for many people. A few years ago we conducted a small study of a common medication called naltrexone and found that low doses provided significant pain relief in the many of the people tested. Therefore, we decided to conduct a larger study of low-dose naltrexone (LDN) for a longer period of time.

Naltrexone has been used safely for many years to treat people who are addicted to alcohol and narcotics because it blocks the effects of these drugs. When given in smaller doses, naltrexone may help to reduce pain associated with inflammatory and autoimmune conditions, such as multiple sclerosis and Crohn’s disease. LDN is not FDA-approved for the treatment of pain, and is still experimental.

In our study, 28 women with fibromyalgia took one pill a day for 16 weeks. During that time, each woman took the LDN (4.5 mg) for 12 weeks and a sugar pill (placebo) for 4 weeks. The study was double-blind, meaning that neither the women participating in the study nor the healthcare team knew which pill they were taking at any time. Each woman was given a handheld computer to record their pain, fatigue, and other symptoms on a daily basis, and they continued to record their symptoms for 4 weeks after they stopped taking the capsules.

The results of the study were similar to the results of our earlier, smaller study—participants experienced a significantly greater reduction in their pain scores while they were taking the LDN as compared with while placebo. They also reported improved general satisfaction with life and improved mood while taking LDN. However, there was no improvement in fatigue or sleep. All participants tolerated the LDN, with few side effects.

LDN is a widely available, inexpensive medication with few side effects that could prove to be a useful treatment for fibromyalgia. More studies are needed to determine if it will provide long-term, safe and effective relief of the pain of fibromyalgia in a majority of patients.

Younger J, Noorulain N, McCue R, Mackey S. Findings of a small, randomized, double-blind, placebo-controlled, counterbalanced, crossover trial assessing daily pain levels. Arthritis Rheum 2013:65(2);529–38.