• Researchers say the drug fluvoxamine is effective as an outpatient treatment for COVID-19.
• Experts say fluvoxamine could widen access to COVID-19 treatments, although they expect it to be a somewhat minor tool in the medical community’s toolkit.
• They also note that more studies need to be done on fluvoxamine’s effectiveness against the Omicron variant.

Fluvoxamine, a selective serotonin reuptake inhibitor (SSRI) commonly used to treat obsessive-compulsive disorder, could find another use as a safe treatment for COVID-19.

A meta-analysis of three previous trials on the drug’s effectiveness for COVID-19 treatment found “a high probability of being associated with reduced hospitalization in outpatients with COVID-19,” a new studyTrusted Source led by researchers from McGill University in Quebec, Canada, found.

The researchers report that fluvoxamine treatment appeared to reduce the risk of severe COVID-19 by about 25 percent if given to people at high risk for COVID-19 early in the course of their infection.

That’s significantly less effective than some current COVID-19 antiviral treatments, such as Pfizer’s antiviral pill, Paxlovid. That drug has been shown to reduce the risk of severe COVID-19 by as much as 89 percent if taken within three days after the onset of symptoms.

Still, “particularly in resource-limited settings or for individuals without access to SARS-CoV-2 monoclonal antibody therapy or direct antivirals,” fluvoxamine might provide an easily accessible alternative, the study authors write.

The fact that the drug is widely available and with a large amount of safety data is another potential benefit since it was approved by the Food and Drug Administration (FDA) in 1994.

How it might work

Just how might a drug used to treat obsessive-compulsive disorder also work against COVID-19?

While fluvoxamine belongs to the SSRI class of drugs that includes Prozac or Zoloft, “chemically it is unrelated to these other drugs,” said Dr. David Cutler, a family medicine physician at Providence Saint John’s Health Center in California.

“In the test tube, fluvoxamine activates the sigma-1 receptor inside cells. This action has been found to inhibit replication of the COVID virus (SARS-CoV-2),” Cutler told. “In addition, sigma-1 activation can modulate the inflammatory response to serious infection in animals.”

A minor tool in the toolkit

However, even with this meta-analysis in hand, experts say fluvoxamine is likely to be a minor tool with which to battle the COVID-19 pandemic.

“Many existing drugs have been used to treat COVID and often initial reports show success,” Cutler said. “This may hold true for fluvoxamine, but it has not proven to be the case for numerous other drugs like hydroxychloroquine, azithromycin, ivermectin, vitamin D, and others which were proclaimed beneficial with great fanfare and later proven useless.”

Amichai Perlman, Ph.D., a pharma domain expert at digital healthcare company K Health, agreed, noting that even with three studies for meta-analysis, the findings require further investigation.

“Because the third trial was larger and also had many more patients who deteriorated, the results of the meta-analysis primarily reflect the results of this study,” Perlman told Healthline. “There are conflicting opinions regarding the ‘Together’ study [the third study in the report]. In its last update, the NIH listed several difficulties interpreting the results of the study and concluded that there is insufficient evidence to recommend either for or against its use for COVID-19.”

There’s also concern that these studies took place before the rise of the Omicron variant of COVID-19, which has rendered ineffective certain prior treatments, such as GlaxoSmithKline’s sotrovimab. That newfound inefficacy led to the FDA revoking its emergency use authorization for the drug.

Fluvoxamine would likely need to clear a hurdle of effectiveness against Omicron to receive FDA approval.

“This small benefit [from this study] may have seemed like especially good news before newer, highly effective therapies became available,” Cutler added. “While fluvoxamine has an advantage of being inexpensive and a long safety record, it cannot deliver anywhere near the proven benefit of Paxlovid and the monoclonal antibodies.”