SynthesisBMJ open2026
Effect of low-dose naltrexone for long COVID: a systematic review and meta-analysis.
Synthesis in BMJ open, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
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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.
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.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
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Authors and funding
5 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveLong covid is a debilitating chronic condition, and the effect of low-dose naltrexone (LDN) on its symptoms is unclear. We aimed to determine the effectiveness of LDN on symptoms of long covid.
designSystematic review and meta-analysis. DATA SOURCES: PubMed, Embase and Cochrane Library for published studies; ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) for registered ongoing studies were searched through 5 May 2026. ELIGIBILITY CRITERIA: We included randomised controlled trials and pre-post studies of patients with long covid reporting on fatigue, quality of life, cognitive symptoms or function and other long covid symptoms. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers used standardised methods to search, screen and select included studies. Risk of bias was assessed using the Newcastle-Ottawa Scale. Meta-analysis was conducted using random effects models.
resultsOf 397 titles and abstracts screened, no randomised controlled trials were identified. Four observational pre-post studies from the USA and Ireland (n=155) met inclusion criteria. LDN doses varied from 1 mg/day to 6 mg/day. Pooled pre-post analyses showed moderate effects for reducing fatigue (Hedges' g=-0.74; 95% CI -1.11 to -0.37; p<0.001), brain fog (Hedges' g=-0.53; 95% CI -1.01 to -0.05; p=0.03) and improving sleep quality (Hedges' g=-0.60; 95% CI -0.91 to -0.30; p=0.0001), and large effects for pain (Hedges' g=-0.93; 95% CI -1.29 to -0.57; p<0.001) and daily functioning (Hedges' g=-0.93; 95% CI -1.29 to -0.57; p<0.0001) in favour of LDN. Heterogeneity ranged from 0% to 62%. No serious adverse events were reported in the two studies that assessed safety.
conclusionLimited evidence from small pre-post studies suggests LDN may improve fatigue, cognition, sleep, pain and functioning in long covid. However, certainty of evidence is low. Well-powered trials are needed to confirm efficacy, determine dosing and duration and identify subgroups most likely to benefit.
trial registrationhttps://doi.org/10.17605/OSF.IO/C2VKX.
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