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Cold, Flu, & Cough Health Center

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Zinc May Prevent and Shorten Colds

Research Shows That Zinc Reduces Cold Symptoms and Cuts Use of Antibiotics

How Zinc Fights Colds

Zinc appears to work in two ways, says Ananda Prasad, MD, PhD, a professor of internal medicine at Wayne State University School of Medicine in Detroit, who has spent his career researching zinc’s effects on the immune system.

First, zinc interferes with the ability of rhinoviruses, which are responsible for about 80% of all colds, to reproduce. Second, it appears to block their ability to dock on cell membranes and subsequently cause infection.

Prasad published a study in 2008 in the Journal of Infectious Diseases, which tested zinc lozenges against placebo in 50 study participants.

Half got 13.3 milligrams of zinc every 3-4 hours in a zinc acetate lozenge; the other half got a dissolvable wafer with inactive ingredients that tasted the same.

“Usually it takes about eight days for a cold to disappear,” Prasad says, “but with zinc, it cuts down by about 50%.”

Study participants who took zinc got over their colds in about four days compared to seven days in the group that got the placebo.

“If you consider how many people lose their days of work because of the common cold, it’s astounding,” Prasad says. “In children and the elderly, the incidence of colds is six to seven a year.”

The news that zinc could make a dent in some of that misery, when not much else does, is exciting, Prasad thinks.

“So far, to my knowledge, there’s nothing [else] that’s effective,” he says.

Experts stress that more research is needed before the most effective kind of zinc can be determined, and they caution that in high doses -- more than 40 milligrams per day -- zinc can cause dizziness, headache, drowsiness, increased sweating, loss of muscle coordination, alcohol intolerance, hallucinations, and anemia.

They also warn against using zinc nasal sprays, which some reports suggest can cause loss of smell, or from using nasal swabs.

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