Coronavirus: To zinc or not to zinc?

Zinc is no COVID-19 magic bullet, but it has shown to help with other coronaviruses.
March 25th, 2020

Calling the specific virus that is causing COVID-19 “coronavirus” is a bit like calling the Ford Explorer “the SUV.” Both statements are true, but with both, one is part of the other. There are lots of different SUVs; there are lots of different coronaviruses.

women taking zinc, which does help with some coronaviruses and could with COVID-19.
Zinc is something that will not hurt you, and there may be some benefit when it comes to COVID-19, like with other coronaviruses. Photo: Getty Images.

Many common colds are caused by coronaviruses. Various scientific studies (we’ll get to those in a moment) have shown zinc lozenges to be effective in shortening the misery phase of common colds. So in the face of a coronavirus pandemic, here’s a big question many are asking: can zinc shorten the duration of – or even diminish the symptom load and thereby lessen the impact – of COVID-19?

The answer is we don’t know yet. But to twist the analogy: if changing the oil helps a Jeep Grand Cherokee avoid the shop, it’s a good bet that doing the same will benefit the Ford Explorer, too.

Dr. Ian Tullberg bears no responsibility for the above comparison. But as far as helping patients get over colds, “there’s good evidence that oral zinc works well,” the medical director of UCHealth Medical Group Urgent Care said.

With respect to the specific coronavirus that is causing the pandemic now, “the problem is that this is still so early that we don’t have the knowledge if it works or not,” Tullberg said. “However, zinc is something that will not hurt you, and there may be some benefit.”

Those who swear by zinc as a cold remedy know to take it when they first start to feel a scratchy throat. They try to hit it early – right when the cold’s coming on. Research spanning decades has shown that using zinc lozenges through the course of the cold does make a difference.

The data around Zinc and coronaviruses

A study published in 1996 shuffled 100 Cleveland Clinic employees who self-reported catching colds into two groups. Fifty took lozenges containing 13.3 milligrams of zinc gluconate – the dosage of today’s Cold-Eeze and other over-the-counter lozenges – every two hours as long as they had cold symptoms. Fifty others took placebo lozenges. The study was double-blind, so neither patients nor researchers knew which patients had the placebo. The findings: the zinc group cleared symptoms more than three days earlier – 4.4 days versus 7.6 days of the placebo group, and, until that point, suffered fewer days with cough, headache, hoarseness, nasal congestion, and sore throat (fever, muscle aches, scratchy throat and sneezing remained similar during the cold’s duration). Zinc has side effects – “bad-taste reactions” (understandable) and, among 20 percent of those taking zinc, nausea.

That study wasn’t, it turned out, a fluke. A Cochrane review updated in 2013 summarized 18 randomized controlled trials involving 1,781 participants across all age groups found that zinc – particularly in lozenge or syrup form – “inhibits replication of the virus” that cause the common cold and shortens average duration of the common cold when taken within 24 hours of onset of symptoms at a dose of more than 75 milligrams a day.

A 2010 study led by University of Leiden Medical researchers in the Netherlands sought to understand how zinc inhibited that replication. The team reported that zinc inhibits a cousin of SARS-CoV-2: SARS-CoV, the original SARS of the 2003 outbreak. Click through for details, which get into the biochemical nitty-gritty, but the gist is that zinc throws a wrench in the virus’s RNA-synthesis machine.

Now, there are caveats with zinc. First, like everything else, there can be too much of a good thing – more than 150 milligrams a day for adult. That’s about 11 lozenges; the recommended zinc-lozenge maximum for adults being six and just four for children ages 12-17 (research has shown younger children to not benefit from taking zinc). Second, zinc nasal sprays shouldn’t be used, Tullberg says. In 2009, the U.S. Food and Drug Administration warned against such products because people who used them lost their sense of smell.

What does that background say about the effectiveness of zinc and the SARS-CoV-2 now known as coronavirus? It is, at best, effectiveness by association. But an email that recently went viral as a blog post indicates that Tullberg is in good company with his openness to zinc lozenges as a way to at least try and mitigate COVID-19 flu symptoms.

A virologist’s take on Zinc and COVID-19

The email was one that James A. Robb sent to friends and family. He is University of Colorado School of Medicine MD, a pathologist, and molecular virologist who, while at the University of California, San Diego in the 1970s, did pioneering work in understanding coronaviruses. He wrote:

For all updates and to read more articles about the new coronavirus, please visit uchealth.org/covid19

Stock up now with zinc lozenges. These lozenges have been proven to be effective in blocking coronavirus (and most other viruses) from multiplying in your throat and nasopharynx. Use as directed several times each day when you begin to feel ANY “cold-like” symptoms beginning. It is best to lie down and let the lozenge dissolve in the back of your throat and nasopharynx. Cold-Eeze lozenges is one brand available, but there are other brands available.

Snopes.com, a website dedicated to debunking (or confirming) internet myths, investigated after his words were twisted by others and reposted with exaggerated claims such as zinc being a “silver bullet” against coronavirus. In an email to Snopes, Robb confirmed that he’d written the above and added, “In my experience as a virologist and pathologist, zinc will inhibit the replication of many viruses, including coronaviruses. I expect COVID-19 will be inhibited similarly, but I have no direct experimental support for this claim. I must add, however, that using zinc lozenges as directed by the manufacturer is no guarantee against being infected by the virus, even if it inhibits the viral replication in the nasopharynx.”

In short, if coronavirus is like an SUV, zinc lozenges may well be something like an oil change, though we’ll need many more miles to really know for sure.

About the author

Since 2008, Todd Neff has written hundreds of stories for University of Colorado Hospital and UCHealth. He covered science and the environment for the Daily Camera in Boulder, Colorado, and has taught narrative nonfiction at the University of Colorado. He was a 2007-2008 Ted Scripps Fellowship recipient in Environmental Journalism at CU.

His latest book, "The Laser That’s Changing the World," tells the story of the inventors and innovators who saw, and ultimately realized, the potential of lidar to help solve problems ranging from smokestack-pollution detection, ice-sheet mapping, disaster recovery, and, ultimately, autonomous-vehicle guidance, among many other uses. His first book, "From Jars to the Stars," recounts how Ball Aerospace evolved from an Indiana jar company - and a group of students in a University of Colorado basement - to an organization that managed to blast a sizable crater in the comet 9P/Tempel 1. "Jars" won the Colorado Book Award for History in 2012.

Todd graduated with a business degree from the University of Michigan, where he played soccer, and with a master’s degree from the Fletcher School of Law and Diplomacy at Tufts University. Before becoming a journalist at the turn of the millennium, he was an IT and strategy consultant. He once spoke fluent Japanese and still speaks fluent German.

When not writing, he spends time with teenage daughters and wife Carol, plays soccer, and allows himself to be bullied by a puggle he outweighs by a factor of seven.