TL;DR
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In a retrospective study of 230 adults treated at Stanford’s Long COVID Clinic, patients reported fewer symptoms and improved functioning after receiving low-dose naltrexone. The study had no control group, so it cannot establish that the drug caused the changes; randomized trials are needed to assess safety and effectiveness.
A retrospective study of 230 adults with long COVID found that patients reported fewer symptoms and better functioning after receiving low-dose naltrexone, according to results presented at the IDWeek annual meeting. The study had no comparison group, however, and cannot show that the medication caused the improvements.
Researchers reviewed electronic health records from Stanford’s Long COVID Clinic, covering patients seen from 2023 through December 2025. Participants were adults with laboratory-confirmed COVID-19 and symptoms lasting at least 90 days. Each had a clinic visit before starting naltrexone and at least one follow-up while taking it. The analysis compared patient-reported symptoms and functioning from baseline to follow-up more than three months after the prescription.
After adjustment for other factors, the average seven-symptom composite score, which was 20 at baseline, declined by an estimated 5.1 points per year. The average number of symptoms fell by an estimated 2.4 per year. Functional-stage scores also improved by an estimated 0.32 points per year on a five-point scale. These are estimated annual changes in the study’s measures, not evidence that every patient improved or that the medication produced the changes.
Reported improvements included fatigue, brain fog, unrefreshing sleep, difficulty sleeping and post-exertional malaise. The researchers did not find statistically significant improvement in headache or lightheadedness. The median final dose was 4 milligrams. Participants’ median age was 45.4, 67% were female, and 85.2% were fully vaccinated against COVID-19. More than half reported reduced daily activity because of long COVID.
What the Patient Reports Show
The results add observational data on a drug some clinicians prescribe off-label to people with long COVID, a condition for which there are no FDA-approved therapies. The reported changes across several symptoms may help identify questions for controlled research, particularly because fatigue, cognitive difficulties and post-exertional malaise can interfere with everyday activities.
But the study does not establish that naltrexone is effective. Without a group receiving placebo or another comparison treatment, researchers cannot separate a possible medication effect from natural changes over time, other care patients received, or factors affecting how symptoms were reported. The findings should not be treated as proof of benefit or a treatment recommendation.
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How the Stanford Study Was Run
Low-dose naltrexone is used below the 50-to-100-milligram doses approved for other indications. Naltrexone is an opioid antagonist approved to treat opioid and alcohol use disorders; in combination with bupropion, it is also used for obesity. Use at lower doses for long COVID is off-label, meaning it is not an FDA-approved treatment for that condition.
Study presenter Brandon Aflak, JD, CNA, a Stanford University fellow, said the drug may have anti-inflammatory or immunomodulatory effects, but this study did not test those mechanisms. The results come amid unsuccessful or inconclusive trials of other proposed long COVID treatments. For example, the source report described a nirmatrelvir-ritonavir trial in which the active-treatment group did not outperform placebo. Such findings underscore why apparent improvement in an uncontrolled patient group needs testing against a suitable comparison.
The National Academies of Sciences, Engineering, and Medicine defines long COVID as a chronic condition following SARS-CoV-2 infection that lasts at least three months and may be continuous, relapsing and remitting, or progressive, affecting one or more organ systems. A 2022 U.S. survey cited in the report found that 6.9% of adults said they had ever had long COVID and 3.4% reported having it that year.
What the Records Cannot Establish
The analysis cannot determine how much of the observed improvement, if any, was caused by naltrexone. There was no control group, and Aflak acknowledged that the natural course of long COVID and concurrent treatments could have affected the results. The retrospective design also relied on clinical records and patient-reported measures rather than a randomized treatment assignment.
The report does not establish whether the findings would apply to people outside this single clinic, how outcomes compare with placebo, or which patients might benefit. It also does not settle the drug’s safety and effectiveness for long COVID. The reported symptom changes should not be interpreted as proof of efficacy, and the study does not provide a basis for patients to start or change medication without clinical guidance.
Controlled Trials Remain the Next Step
The next evidence needed is a randomized, placebo-controlled trial that follows participants with long COVID over a defined period and compares symptoms, functioning and safety between groups. Such research could help distinguish a drug effect from natural fluctuation or other care and clarify which outcomes change, for whom, and at what dose.
The material provided does not identify a planned trial or a timeline for one. Until controlled results are available, the Stanford findings remain an observational signal rather than confirmation that low-dose naltrexone treats long COVID.
Key Questions
Did the study prove that low-dose naltrexone improves long COVID?
No. Patients reported improvements, but the retrospective study had no control group and cannot show that the medication caused them.
Which symptoms improved in the study?
Researchers found reported improvement in fatigue, brain fog, unrefreshing sleep, difficulty sleeping and post-exertional malaise. They did not find statistically significant improvements in headache or lightheadedness.
Is low-dose naltrexone FDA-approved for long COVID?
No. Naltrexone is approved for other uses, but its use for long COVID is off-label. This study does not establish it as an approved or proven treatment for the condition.
What research is needed next?
A randomized, placebo-controlled trial is needed to test whether the drug causes improvements and to assess its safety and potential role in care for long COVID.
Source: medpagetoday.com
