Metformin shown to prevent Long COVID across risk groups in multiple randomized trials

Multiple randomized clinical trials and electronic health record studies now show that metformin, a widely used and well-established medication, significantly reduces the risk of developing Long COVID when taken during or shortly after acute infection with SARS-CoV-2. The findings were published today in Clinical Infectious Diseases External link that opens in the same window.

In the paper, the University of Minnesota Medical School research team provides information about metformin and summarizes several studies in low, standard and high risk populations that show taking metformin during or soon after infection with SARS-CoV-2 prevents the development of Long COVID. Notably, the research summarizes the number of patients needed to receive treatment in each study to prevent one case of Long COVID. On average across the four studies, one case of Long COVID is prevented for every 50 cases of acute SARS-CoV-2 treated with 14 days of metformin.

“Metformin has emerged as the first intervention to prevent Long COVID in low to high risk adults and across multiple clinical trials and high-quality electronic health record studies,” said Carolyn Bramante, MD, MPH, an assistant professor at the University of Minnesota Medical School and physician with M Health Fairview. “This body of evidence means that starting metformin at the time of infection can reduce the risk of Long COVID for most adults who get COVID-19 today.”

Other key findings from the literature on using metformin to treat an acute infection:

• Compared to placebo, metformin significantly decreases SARS-CoV-2 viral load and prevents rebound of viral load.
• Metformin is the first intervention to be tested in two large, placebo-controlled, randomized trials in low-, standard-, and high-risk adults, including adults with prior infection for preventing Long COVID.
• Two of these research studies included persons who were also given FDA-approved treatments of SARS- COV-2 (including nirmatrelvir-ritonavir, molnupiravir, and remdesivir).
• Most adults can take metformin, but should ask their clinician.
• Metformin during acute COVID-19 is safe and does not cause low blood sugar or serious side effects.

The conclusion from these four studies – that treating SARS-CoV-2 with 14 days of metformin can prevent Long COVID – applies to most adults being infected with COVID-19 in the current state of the pandemic. The research team also notes that metformin can be used alone or combined with other treatments of acute SARS-CoV-2.

It is not known whether metformin can prevent Long COVID in pediatric populations, nor if metformin treats Long COVID in either adults or pediatric populations.

Reference:

Carolyn T Bramante, David R Boulware, Preventing Long COVID With Metformin, Clinical Infectious Diseases, 2026;, ciaf700, https://doi.org/10.1093/cid/ciaf700