A widely used diabetes medication may have more medical uses than doctors first thought as scientists discoverit may be able to prevent long covid, but there’s a catch. It needs to be taken early in order to have a significant effect, which could cut the risk of long-covid by 40% to 50%.

Metforminis normally used to treat type 2 diabetes and a handful of other conditions. It’s main purpose is to increase insulin sensitivity, however, since the 2000s researchers have found it also has an effect on the immune function and cellular metabolism, giving it antiviral properties.

When Covid-19 first emerged, early research suggested metform could be effective against the infection according to News Medical. Additionally, the fact that it is already widely available and has a low cost made it a great candidate for further trials.

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Long Covid was first identified in 2020 as cases of people still experiencing serious illness, symptoms and conditions lasting weeks, months or even years after contracting Covid-19 started to emerge. Common symptoms of long Covid include fatigue, shortness of breath, chest pain and cognitive impairment, also known as brain fog.

It can greatly affect a person’s long-term quality of life, functional capacity and even their ability to work. Since its discovery, researchers have been trying to understand the underlying mechanisms of long covid and find preventative measures.

In the Clinical Infectious Diseases journal, researchers reviewed evidence from randomised trials and real-world analyses to see if metformin could also play a role in long Covid. One of which is the COVID-OUT trial which started in 2021. It found that metformin reduced the risk of long Covid by 41% over 10 months but was even more powerful when taken early on in an infection.

People who started taking the drug within three days of their symptoms starting had an even higher risk reduction of 63%. This highlighted the importance of early treatment according to the researchers.

The COVID-OUT trial also found that metformin reduced viral load, which is the amount of virus present in bodily fluids. However, it only focused on participants with a BMI of 25 or higher and excluded people who previously had a Covid-19 infection.

Another randomised trial called ACTIV-6 was used to confirm these results, looking at metformin’s effect in a more diverse population, but used the same 500mg dose that the COVID-OUT trial used.

The second trial found people on metformin had a 50% lower risk of being clinically diagnosed with long Covid. But there was some uncertainty in the results so it supported the COVID-OUT findings but did not definitely prove it.

Both trials used a 500mg dose, starting with a low dose and gradually increasing over 14 days. In total, participants had 36 doses of metformin which didn’t cause significant stomach issues or other safety concerns.