Can Zinc Lozenges Ward Off Coronavirus? What Doctors Say

They may soothe a sore throat, but can zinc lozenges actually shorten the length of a viral infection? The question is getting a fresh look after coronavirus researcher James Robb's email suggesting the mineral supplement to friends and family leaked online.

Robb was one of the first pathologists to study coronavirus in the 1970s. His work has been published in the established scientific journal Virology, and he has worked as a consulting pathologist to the National Cancer Institute. So his informal note to friends was quickly taken seriously online.

The email gives several tips for stopping the spread of novel coronavirus COVID-19. They include specific tips about washing everyday household items where germs lurk, avoiding shaking hands, and using tissues when you sneeze.

The item that got the most attention online, though, was a detailed paragraph on the importance of zinc lozenges. Here, Robb offers specific instructions for taking these lozenges, including lying down and letting the medicine "dissolve in the back of your throat and nasopharynx."

Robb identifies a specific brand in the email, but notes that other brands are available as well. This has prompted social media memes of the named brand that suggest it is a "silver bullet" against coronavirus.

Do Zinc Lozenges Work for Viral Infections?

Short-term oral zinc treatment has been shown to shorten the length of rhinovirus colds when taken at the proper dose by adults, according to Medscape author Joseph Adrian L Buensalido, MD.

The treatment seems to work when at least 75mg of elemental zinc is taken within the first 24 hours of cold symptoms developing, Dr. Buensalido said. He said the improvement was not seen in children.

"Zinc has also been associated with faster resolution of nasal congestion, nasal drainage, and sore throat, as well as improvement of cough," Dr. Buensalido said.

But be careful. More than 150mg/day of zinc may lead to zinc toxicity, with side effects including reduced immune function, according to the NIH. That could leave you worse off than when you started.

Zinc has been proposed as an antiviral medication in the past, according to MedicineNet medical author Melissa Conrad Stöppler, MD.

She said evidence suggests zinc can work as a lozenge, tablet, or syrup to reduce the severity of colds and their duration. However, she offers several precautions as well. Zinc can cause side effects, and the FDA warned against some zinc cold products in 2009 because of it.

"Certain side effects and toxicities, including loss of sense of smell, have been associated with some zinc preparations used to treat colds," Dr. Stöppler said. "In fact, the U.S. FDA has issued a public health advisory warning that three zinc-containing products for topical (intranasal) use should not be used due to the risk of developing this side effect."

The NIH notes that children and the elderly with zinc deficiency in the developing world have been shown to be more vulnerable to pneumonia and other infections. The agency reports zinc allows the body to produce and activate T-cells (t-lymphocytes), which are some of the white blood cells that respond to infections.