Evidence map›Paper›PMID 42385209›Full record

Trial reportEuropean journal of pain (London, England)2026

Efficacy of Low-Dose Naltrexone in Women With Fibromyalgia Syndrome: A 12-Month Randomised, Double-Blind, Placebo-Controlled Single-Centre Clinical Trial (INNOVA Study).

Carla Rodríguez-Freire, Jaime Navarrete, Antoni Rozadilla-Sacanell, Juan P Sanabria-Mazo, Beatriz Del Pino-Gaya, Xavier Borràs, Albert Feliu-Soler, Juan V Luciano

Abstract readRandomized Controlled Trial
In one paragraph

Trial report in European journal of pain (London, England), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Review
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Carla Rodríguez-FreireTeaching, Research & Innovation Unit, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.ORCID https://orcid.org/0009-0006-6728-5778
Jaime NavarreteTeaching, Research & Innovation Unit, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.ORCID https://orcid.org/0000-0002-9482-4822
Antoni Rozadilla-SacanellDepartment of Rheumatology, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.ORCID https://orcid.org/0000-0002-7555-189X
Juan P Sanabria-MazoUnit for the Study and Treatment of Pain-ALGOS, Department of Psychology, Research Center for Behavior Assessment (CRAMC), Universitat Rovira i Virgili, Tarragona, Spain.ORCID https://orcid.org/0000-0003-1688-435X
Beatriz Del Pino-GayaDepartment of Pharmacy, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.
Xavier BorràsCentre for Biomedical Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain.ORCID https://orcid.org/0000-0003-3972-1385
Albert Feliu-SolerCentre for Biomedical Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain.ORCID https://orcid.org/0000-0003-2810-7670
Juan V LucianoTeaching, Research & Innovation Unit, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.ORCID https://orcid.org/0000-0003-0750-1599

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundLow-dose naltrexone (LDN) has been used off-label for fibromyalgia syndrome (FMS) for over a decade, supported by small crossover trials. The INNOVA study evaluated the safety and efficacy of LDN 4.5 mg versus placebo on pain intensity over 12 months in women with FMS.

methodsIn total, 98 women with FMS were randomised to LDN 4.5 mg/day (n = 48) or placebo (n = 50). The primary outcome was change in pain intensity (NRS 0-10) from baseline to 3 months in the intention-to-treat population. Secondary outcomes included functional impairment (FIQR), anxiety-depressive symptoms (DASS-21), cognitive impairment (MISCI), disability (WHODAS 2.0), pathological worry (GAD-7) and impression of change (PGIC/PSIC), assessed at baseline and at 3, 6 and 12 months. Perceived treatment allocation and safety were also assessed.

resultsAt 3 months, mean change in pain intensity was -0.33 points with LDN and -0.64 with placebo, with an adjusted between-group difference of 0.49 (p = 0.236, d = 0.19). Secondary outcomes showed minor and inconsistent changes, with low and similar responder rates (p = 0.219-0.954). Exploratory analyses suggested some improvement among participants who believed they had received LDN, although effects were inconsistent. Adverse events, predominantly mild and transient, were reported by 33 (68.8%) participants in LDN and 36 (72%) in placebo, and no treatment-related serious events occurred.

conclusionsLDN was well tolerated but did not demonstrate a clinically meaningful benefit over placebo for pain-related outcomes, underscoring the need for more effective pharmacological treatments. SIGNIFICANCE STATEMENT: This RCT provides the first long-term evidence on the efficacy and safety of LDN in FMS. LDN (4.5 mg), administered as an add-on treatment, has a favourable safety profile, but the findings indicate that it does not produce clinically meaningful improvements in FMS symptoms compared to placebo at short- or long-term follow-up. These findings contribute to the growing body of evidence questioning its clinical utility.

Indexed as

FibromyalgiaNaltrexoneNarcotic AntagonistsAdultDouble-Blind MethodFemaleHumansMiddle AgedPain MeasurementTreatment OutcomeNaltrexoneNarcotic Antagonistschronic painfibromyalgia syndromelow‐dose naltrexonerandomised controlled trial

Identifiers

PMID42385209
PMCPMC13322712

What OpenQuestion holds

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Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.