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Low-dose naltrexone improves fatigue, cognition, sleep, pain, and functioning in long COVID patients

A systematic review and meta-analysis of four observational pre-post studies (n=155) found that low-dose naltrexone (1-6 mg/day) was associated with moderate to large improvements in long COVID symptoms. Pooled effect sizes showed significant reductions in fatigue (Hedges' g=-0.74), brain fog (Hedges' g=-0.53), and sleep quality (Hedges' g=-0.60), as well as large effects for pain (Hedges' g=-0.93) and daily functioning (Hedges' g=-0.93). No serious adverse events were reported in the two studies that assessed safety.

Last updated: Jul 21, 2026•0 RCTs•1 Meta-analyses•📖 Read as article →

Evidence Score

Evidence Score49/100
Human RCT☆☆☆☆☆
Meta-analysis★★★☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Effect of low-dose naltrexone for long COVID: a systematic review and meta-analysis.

observational

Byambasuren O, Atkins T, Baptista S, Glasziou P, Chakraborty S · BMJ open (2026)

Participants: N/A
Duration: Not specified in abstract
Intervention: Low-dose naltrexone (LDN) at doses ranging from 1 mg/day to 6 mg/day
Outcome: Fatigue, brain fog, sleep quality, pain, daily functioning
Effect Size: Hedges' g=-0.74 for fatigue, -0.53 for brain fog, -0.60 for sleep quality, -0.93 for pain and daily functioning
Population: Patients with long COVID (n=155 from USA and Ireland)

Result:

PubMed: 42463201DOI: 10.1136/bmjopen-2025-111253

Mechanism Graph

Naltrexone blocks opioid receptors at low doses
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This may modulate glial cell activity and reduce neuroinflammation
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Reduced inflammation could alleviate long COVID symptoms
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Result: Improvement in fatigue, cognition, sleep, pain, and functioning

Limitations

  • ⚠No randomized controlled trials were identified; only observational pre-post studies
  • ⚠Small sample size (n=155) with high risk of bias
  • ⚠Heterogeneity ranged from 0% to 62%, indicating variability across studies
  • ⚠Certainty of evidence is low due to study design and lack of control groups

Frequently Asked Questions

What is low-dose naltrexone?▼

Low-dose naltrexone (LDN) is a medication typically used at doses of 1-6 mg/day, which is much lower than the standard dose for opioid addiction (50 mg/day). It is thought to modulate immune function and reduce inflammation.

How effective is LDN for long COVID fatigue?▼

The meta-analysis found a moderate effect size (Hedges' g=-0.74) for reducing fatigue, suggesting a meaningful improvement, but the evidence is from small pre-post studies and certainty is low.

Are there any side effects of LDN for long COVID?▼

No serious adverse events were reported in the two studies that assessed safety, but the abstract does not detail minor side effects. More research is needed.

What is the recommended dose of LDN for long COVID?▼

Doses in the included studies ranged from 1 mg/day to 6 mg/day, but the optimal dose and duration are not yet established and require further trials.

Products

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References

  1. 1.Byambasuren O, Atkins T, Baptista S, Glasziou P, Chakraborty S. "Effect of low-dose naltrexone for long COVID: a systematic review and meta-analysis.." BMJ open, 2026. PMID: 42463201 DOI: 10.1136/bmjopen-2025-111253
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.