Low-Dose Naltrexone Reduces the Symptoms of Fibromyalgia
Fibromyalgia Symptoms are reduced by low-dose naltrexone: A pilot study.
Pain Medicine (2009)
Jarred W. Younger and Sean C. Mackey
People with fibromyalgia complain of chronic pain in the muscles of their body. They are also often profoundly fatigued, and have difficulty sleeping well. Headaches, stomach problems, and a number of other symptoms are frequently reported. Millions of people in the United States meet the criteria for fibromyalgia, and the condition seems to affect more women than men. The disorder can be debilitating, as the pain and fatigue prevent the individual from carrying out their normal activities. There are three FDA-approved medications for fibromyalgia, but not all individuals respond well to those treatments.
What is low-dose naltrexone?
We tested a medication called low-dose naltrexone (LDN). Naltrexone is a medication that has been used for many years to treat opioid addiction. When given at a smaller dose (usually 4.5mg), the drug 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. LDN capsules are typically taken once per day.
What was the study?
We ran a small study to see if individuals with fibromyalgia would receive benefit from taking LDN. Ten women were enrolled in the study – all of whom met the criteria for fibromyalgia. The participants were given a handheld computer to record their pain, fatigue, and other symptoms on a daily basis. They filled out the daily report for two weeks before receiving capsules. Then they received capsules to take once daily. The participants received placebo for two weeks, and then LDN for 8 weeks. The study was single-blind, so participants did not know when they were receiving placebo or LDN. Finally, participants stopped taking the capsules and continued to fill out the daily reports for two more weeks.
Did the drug work?
We were very encouraged by the results. In six out of ten participants, LDN was significantly better than placebo at reducing fibromyalgia symptoms. LDN reduced daily pain, the highest level of pain, fatigue, and stress. Other symptoms, such as sleep problems, gastrointestinal complaints, and headaches, also seemed to be helped.
Pain Medicine (2009). Overall, self-reported, daily fibromyalgia symptoms (scale 0 – 100, with 100 being most severe symptoms). Time periods are: baseline, placebo, LDN, and washout. The data are separated into drug responders (solid line, 6 people) and drug nonresponders (broken line, 4 people). Drug responders are individuals who had at least a 30% greater reduction of symptoms during LDN versus placebo.
What were the side-effects?
We did not observe any serious side-effects during the course of the study. The most commonly reported side-effect (reported by 2 participants) was more vivid dreams. All of the participants who started the study finished the entire 14-week protocol.
Who was involved?
This study was conducted by lead investigator Jarred Younger, PhD and Sean Mackey, MD, PhD. Both investigators are in the Department of Anesthesia, Division of Pain Management at the Stanford University School of Medicine in Palo Alto, CA. The experiment was conducted at the school of Medicine. The capsules were prepared by Preuss Pharmacy in Menlo Park, CA.
We were fortunate to have a number of donors that supported this work. Because naltrexone is a generic drug (in other words, not owned by a pharmaceutical company), it is difficult to secure funds to test the drug. We received critical financial support from a gift given by Jim and Connie Binns. We also received financial and logistical support from the American Fibromyalgia Syndrome Association (AFSA), a not-for-profit organization that specializes in funding studies of fibromyalgia treatments. The Oxnard Foundation provided additional support for the study.We are currently seeking additional funding to support our continued investigation into the efficacy of low-dose naltrexone for fibromyalgia and other conditions. If you are interested in supporting our research please contact us at
Are there any warnings?
We recognize that chronic pain hugely impacts not only patients but their families and friends as well. Often people seek out the newest research and treatments in the hopes of reducing their pain and suffering. While we are excited about the results of this study, we believe some cautions are in order in interpreting our results. This study was very small; only ten fibromyalgia patients were tested. Therefore, the results must be replicated on a larger scale, with more people. There are also a number of questions to be answered regarding proper dosing, interactions with other medications, and whether or not beneficial effects are maintained over a long period of time.
Consequently, this study should not be interpreted to suggest that LDN is a well-accepted treatment for fibromyalgia pain and fatigue. Although we are pleased with the results of this pilot trial, it is still too early to say how effective LDN will be for individuals not in this study.
We are currently running a double-blind trial and are enrolling participants for that study. We expect that study to be finished by the end of 2009. Individuals with fibromyalgia who are close to Stanford University can participate in the trial. More information can be found at: http://snapl.stanford.edu/ldn/
We will continue to test LDN and similar medications, as we seek to develop treatments for chronic pain that are highly effective, easily available, and have a low incidence of side-effects.
General inquiries and inquiries regarding financial support of our research should be directed to