Review of studiesLow-dose naltrexone2024

Vatvani 2024: pooled trials of low-dose naltrexone for fibromyalgia

Vatvani AD, Patel P, Hariyanto TI, Yanto TA. Efficacy and safety of low-dose naltrexone for the management of fibromyalgia: a systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

What it found

Pooling 4 randomized trials with 222 people with fibromyalgia, low-dose naltrexone lowered pain scores more than placebo (mean difference -0.86). It did not improve overall fibromyalgia impact or pain catastrophizing scores, and it was linked to more vivid dreams and nausea.

Trials pooled: 4
People: 222
Pain score difference vs placebo: MD -0.86
Pressure pain threshold difference: MD 0.17

What they tested

A meta-analysis pools the results of many trials. The authors searched Scopus, Medline, ClinicalTrials.gov and the Cochrane Library up to 20 May 2024 for randomized trials comparing low-dose naltrexone with a placebo in people with fibromyalgia, a long-term condition of widespread pain.

They combined results with random-effects models, a method that allows for differences between trials, and reported mean differences and odds ratios.

What they found

Pain scores dropped more with low-dose naltrexone than with placebo (mean difference -0.86; 95% confidence interval -1.20 to -0.51).

Pressure pain threshold, how much pressure it takes before something starts to hurt, rose more with low-dose naltrexone (mean difference 0.17; 95% confidence interval 0.08 to 0.25).

Scores on the revised Fibromyalgia Impact Questionnaire, which measures how the condition affects daily life, and on the pain catastrophizing scale did not differ significantly between the groups.

Vivid dreams and nausea were more common on low-dose naltrexone. Serious adverse events, headache, diarrhoea and dizziness did not differ significantly from placebo.

The authors later published a correction to one of the review's results. They said it did not change the review's conclusions.

Limits

Only 4 trials with 222 people were pooled, so the estimate rests on a few small studies.
The drop in pain scores was not matched by a significant change in how much fibromyalgia affected daily life.
One pooled result was corrected after publication in a separate correction notice.

What it means if you're considering naltrexone

This review is more positive about low-dose naltrexone for fibromyalgia than two of the larger single trials, the Danish trial and INNOVA, which each found no clear benefit over placebo. It also confirms that vivid dreams and nausea are the side effects to expect.

Low-dose naltrexone is a separate use from the standard tablet taken for alcohol, and this review says nothing about drinking.

Frequently asked questions

Does low-dose naltrexone reduce fibromyalgia pain?

This pooled analysis of 4 trials found a modest drop in pain scores compared with placebo, but no significant change in the overall impact of fibromyalgia. Some single trials, including a Danish trial in women, found no clear benefit.

What side effects does low-dose naltrexone cause?

In the pooled fibromyalgia trials, vivid dreams and nausea were more common than on placebo. Serious adverse events, headache, diarrhoea and dizziness were not.

The paper

Read the review doi:10.3344/kjp.24202

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.