A widely used and affordable antidepressant, Fluvoxamine, may offer much-needed relief to people struggling with long COVID, according to a new study published on March 31 in Annals of Internal Medicine.

For millions dealing with lingering symptoms after a COVID-19 infection, persistent fatigue has been one of the most frustrating and life-disrupting challenges. Now, researchers say there’s a promising development.

“This is an important step forward for patients who have been desperate for evidence-based options,” said Edward Mills, a professor at McMaster University. He noted that fluvoxamine not only showed “consistent and meaningful benefits,” but also holds real potential for clinical use since it’s already widely available and well understood.

The study followed nearly 400 adults in Brazil who had been experiencing fatigue for at least three months after recovering from COVID-19. Participants were split into three groups and given either fluvoxamine, the diabetes drug Metformin, or a placebo over a 60-day period.

The results were striking. Patients who took fluvoxamine reported noticeable improvements in fatigue within two to three months. In fact, researchers found a 99% probability that the drug performed better than the placebo.

On the other hand, metformin—despite earlier evidence suggesting it might reduce the risk of developing long COVID—did not significantly improve fatigue in those already affected.

“This trial gives clinicians their first strong evidence for a medication that helps reduce long COVID fatigue,” said Jamie Forrest, a postdoctoral fellow at the University of British Columbia. “Patients want something they can try today—and this finding brings us closer to that reality.”

Still, experts urge caution. While the findings are encouraging, more research is needed to understand exactly how fluvoxamine works in this context and which patients are most likely to benefit.

For now, though, the study offers a rare dose of optimism in the ongoing effort to tackle the long-term effects of COVID-19.