Early Metformin Linked to Lower Long COVID Risk

Adults recently infected with COVID-19 saw fewer cases of long COVID or death in an observational U.S. study.

Updated on Nov. 4, 2026 in COVID-19

Plain white oval tablets rest on a pale ceramic surface beside a glass of water in soft window light. — A large U.S. observational study found adults prescribed metformin within six days of COVID-19 infection had lower odds of developing long COVID or dying within 180 days. AI Illustration. Upload story photo >

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If you caught COVID, would you ask a doctor about taking metformin to lower your risk?

Adults who were prescribed metformin within six days of a SARS-CoV-2 infection had a lower risk of developing long COVID or dying within 180 days, according to an observational study of U.S. electronic health records published October 29 in the Journal of Medical Virology. The findings are preliminary and come from a non-randomized analysis.

Why it matters

Long COVID remains a persistent concern for many people after infection, and the study adds observational evidence to a question that randomized trials have been testing. Because the analysis emulated two completed randomized trials, it helps show whether their results appear in real-world patient data, though it cannot establish cause and effect.

This observational cohort study used deidentified U.S. electronic health records to compare 248 adults prescribed metformin within six days of infection against 9,412 adults prescribed fluticasone, fluvoxamine, ivermectin, or montelukast. After statistical weighting, long COVID or death occurred in 4.0% of the metformin group versus 8.5% of the control group, an adjusted risk ratio of 0.47 over 180 days. The results are preliminary and non-randomized.

The players

University of Minnesota Medical School

A major academic medical center whose researchers have contributed to long COVID and infectious disease studies.

Journal of Medical Virology

A peer-reviewed journal publishing research on viral infections and their clinical effects.

The details

The study was designed to emulate the COVID-OUT and ACTIV-6 randomized trials, which tested metformin against placebo for preventing long COVID. Researchers excluded patients who had standard indications for metformin, including diabetes, and used entropy balancing to match the two groups on age, sex, race and ethnicity, body mass index, prior medications, existing conditions and laboratory results. Long COVID was identified using the ICD-10 code U09.9 or a computable phenotype based on new or worsening symptoms and conditions.

Metformin or control prescriptions were counted when issued within days 0 to 6 after infection.
Outcomes were tracked over a 180-day follow-up window.
The study was published online October 29, 2026, in the Journal of Medical Virology.

Health Landscape

The study sits alongside the COVID-OUT and ACTIV-6 randomized trials, which investigated metformin and other inexpensive, repurposed medications as possible early treatments to reduce long COVID. Its emulation approach offers a way to check whether trial-level signals hold up in the broader population of patients receiving routine care.

If you have recently been diagnosed with COVID-19 and are concerned about long-term symptoms, this is worth discussing with your doctor, who can weigh whether any early treatment is appropriate for your situation. The results are observational and should not be read as a reason to start or change any medication on your own.

The takeaway

Observational data suggest early metformin use after COVID-19 infection may be linked to lower long COVID risk, but this is not yet proven. Anyone with a recent infection who has questions about long-term symptoms should consult a clinician.