Randomized trialLow-dose naltrexone2013
Younger 2013: low-dose naltrexone for fibromyalgia pain
Younger J, Noor N, McCue R, Mackey S. Low-dose naltrexone for the treatment of fibromyalgia: findings of a small, randomized, double-blind, placebo-controlled, counterbalanced, crossover trial assessing daily pain levels
What it found
In 31 women with fibromyalgia, low-dose naltrexone (4.5 mg a day) reduced baseline pain by 28.8%, against 18.0% on placebo. It also improved mood and satisfaction with life, but not fatigue or sleep.
- Pain reduction on low-dose naltrexone
- 28.8%
- Pain reduction on placebo
- 18.0%
- Met response criteria, low-dose naltrexone
- 32%
- Met response criteria, placebo
- 11%
What they tested
31 women with fibromyalgia took part in a crossover trial, meaning each woman spent time on both low-dose naltrexone (4.5 mg a day) and a placebo, in a random order, without knowing which was which. They rated their pain every day so the researchers could track it closely.
The trial repeated and extended an earlier one. Besides pain, it measured general satisfaction with life, positive mood, sleep quality and fatigue.
What they found
Pain fell from baseline by 28.8% on low-dose naltrexone and by 18.0% on placebo (P = 0.016).
Low-dose naltrexone also improved general satisfaction with life (P = 0.045) and mood (P = 0.039). It did not improve fatigue or sleep.
32% of women met the response criteria (a significant drop in pain plus a significant drop in fatigue or sleep problems) while on low-dose naltrexone, against 11% on placebo (P = 0.05).
Women rated low-dose naltrexone as tolerable as placebo, and no serious side effects were reported.
Limits
- It was small: 31 women, and no men.
- The authors called the evidence preliminary and said parallel-group trials, where each person gets only one treatment, are needed.
What it means if you're considering naltrexone
Low-dose naltrexone is compounded and used off-label, at a far smaller dose than the 50 mg tablets used for alcohol. This trial is one of the early positive results for fibromyalgia pain.
The site's low-dose naltrexone guide notes that three later trials did not find a clear benefit, so this small study on its own isn't strong evidence that it works.
Frequently asked questions
Does low-dose naltrexone help fibromyalgia?
In this small trial of 31 women, pain fell 28.8% on low-dose naltrexone against 18.0% on placebo. The authors called the evidence preliminary, and later trials described in the site's guide did not find a clear benefit.
The paper
Younger J, Noor N, McCue R, Mackey S. Low-dose naltrexone for the treatment of fibromyalgia: findings of a small, randomized, double-blind, placebo-controlled, counterbalanced, crossover trial assessing daily pain levels. Arthritis Rheum. 2013;65(2):529-538. doi:10.1002/art.37734
Read the paperdoi:10.1002/art.37734
We wrote this page from the paper's published abstract, and the study's numbers here come from there. Updated October 17, 2026.
Medical disclaimer
This page is for information only and is not medical advice, diagnosis, or treatment. Don't start, stop, or change any medicine — including naltrexone — without your prescriber. Naltrexone must not be used by people taking opioid pain medicines, people dependent on opioids, or people in opioid withdrawal (FDA label). In an emergency call 911; for crisis support call or text 988. Full medical disclaimer.