Zinc for Colds: Lozenges & Nasal Sprays

You've probably heard a lot about zinc for colds. But is zinc really effective for reducing the duration of cold symptoms? Here's what you should know about zinc and colds.

Zinc is an essential mineral that is found in almost every cell. Zinc has antioxidant effects and is vital to the body's resistance to infection. It's also important for tissue repair.

Zinc is found naturally in shellfish, beef and other red meats, nuts and seeds, beans, and milk and cheese. Tea, coffee, and certain medications may interfere with zinc absorption in the intestines.

Researchers have studied the use of zinc as a cold remedy and as a way to treat the cold virus. Still, the data from years of scientific studies is mixed.

In some studies, researchers found that zinc lozenges or nasal sprays decreased the duration of colds. In other studies, they found no differences in cold symptoms between those who took zinc and those who took a placebo or sugar pill.

What do these findings on zinc and colds mean to you and your family? For now, the study results on using zinc as a cold remedy are inconclusive. For every study showing a positive benefit with zinc, there's another study showing no benefit at all. In fact, it's believed that if there is any benefit in taking zinc or zinc lozenges, it is very minor.

The effectiveness of zinc as a cold remedy relies on frequent dosing during the illness, which means zinc lozenges must be taken every two to four hours. Short-term use of zinc — less than 5 days — has not lead to serious side effects but can cause mouth irritation and stomach upset. However, experts recommend that zinc should not be taken for more than 5 days. Long-term use of zinc — for more than 6 weeks — can lead to copper deficiency.

Zinc nasal sprays are known to cause a loss of the sense of smell in animals, and there have been several reports of people losing their sense of smell from zinc nasal sprays. Due to this risk of a loss of smell, many experts recommend that you avoid zinc nasal sprays completely.

Zinc supplements are not recommended for children as they are even more sensitive to zinc and develop side effects at much lower zinc levels.

Yes, zinc is necessary for optimal health and is safe to take when ingested through food sources such as seafood and eggs. But supplementing with higher doses of zinc, particularly long term, can be toxic.

While some research has shown some benefit from zinc lozenges and nasal sprays, studies have been inconsistent and additional research is needed to see if, in fact, zinc is an effective cold remedy. Zinc's side effects may outweigh any potential benefit and the benefit may be minimal at best.

WebMD Medical Reference

Sources: NIH Office of Dietary Supplements: "Zinc." American Family Physicians: "Treatment of the Common Cold." Scientific American: "No proof zinc lozenges help cold symptoms." US Pharmacist: "Zinc and the Common Cold: What Pharmacists Need to Know." Medscape: "Efficacy of Zinc Lozenges Against Common Cold Viruses." Oregon State University, Micronutrient Information Center: "Zinc."

Reviewed by Michael W. Smith, MD on December 18, 2007

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