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Zinc for the Common Cold

Scientific studies show the benefits of zinc for the common cold are modest but real. They don't yet show the best dose.

People have been searching for a cure for the common cold for centuries. To date, we have seen nothing that actually overcomes cold viruses the way antibiotics conquer bacteria. (By the way, antibiotics are useless against viral infections like colds.) However, for years scientists have been evaluating reports about zinc for the common cold. Scientists now have found enough evidence to support its use, especially when cold symptoms are worst.

What Can You Take to Calm Cold Symptoms?

Q. I just came down with a nasty cold. I immediately tested for COVID and was negative. That was a relief, but my nose is running and I am coughing up a storm. What herbs are good for calming cold symptoms?

A. Our favorite herbal supplements for colds contain echinacea, elderberry, ginger and Andrographis paniculata. A review in the journal BMC Complementary Medicine and Therapies (April 7, 2021) concluded that elderberry may reduce the severity and duration of colds.

Don’t forget the zinc lozenges. Randomized controlled trials have found that zinc can help people recover sooner (BMJ Open, Nov. 2. 2021). Studies have confirmed that adequate zinc is essential for good antiviral immune response (Advances in Nutrition, July 1, 2019). During the COVID-19 pandemic, people with low stores of zinc were more susceptible to severe infection (Nutrients, March 21, 2023).

Evidence on Zinc for the Common Cold:

Researchers have been interested in the possible effectiveness of zinc for preventing or treating SARS-CoV-2. Consequently, an international team of investigators reviewed the medical research on this topic. Researchers conducted trials of zinc against COVID-19. The results included a lower mortality rate among people taking zinc (European Journal of Medical Research, May 23, 2022). Unfortunately, however, another study did not find that high-dose zinc gluconate, ascorbic acid or the combination sped recovery from COVID (JAMA Network Open, Feb. 1, 2021).

However, the scientists analyzed 28 randomized controlled trials covering more than 5,000 participants. The studies tested a variety of zinc formulations and doses against common respiratory tract infections, mostly colds. People who took zinc as a preventative were less likely to come down with sniffles and sneezes. Zinc tablets or nasal spray prevented about five colds (or other infections) per 100 person-months. The number needed to treat was 20, which is quite respectable.

According to the reviewers, taking zinc under the tongue or as a nasal spray once symptoms began shortened illness duration by about two days. That is certainly not a dramatic improvement, but many people might welcome that. These studies revealed no serious adverse reactions, though zinc can cause nausea, vomiting and irritation of the mouth or nose.

How Much Zinc for the Common Cold?

For at least a decade, researchers have said they don’t have enough data to recommend a dosing regimen. Unfortunately, that is still true. The studies in the meta-analysis employed different doses and formulations but did not test them against each other. In our experience, zinc for the common cold works best if taken within 24 hours of the first symptoms.

A Sniff of Zinc:

Although many people are enthusiastic about zinc-based nasal sprays, we worry about a potential loss of the sense of smell. Back in 2009, the FDA warned people against using one of the most popular brands, Zicam. We received a question right around that time.

Q. A friend of mine took Zicam for a cold last fall and the next day woke to find she had completely lost her sense of smell. It has not returned.

Her sense of taste was also compromised and she has to overseason her food now to taste it. Do you have any suggestions?

A. We don’t know of any treatments to restore the sense of smell. The FDA has warned consumers not to use certain Zicam products (Cold Remedy Nasal Gel, Cold Remedy Nasal Swabs, and kids size Nasal Swabs). At that point, the agency had received more than 130 reports of loss of the sense of smell associated with these zinc-containing nasal products. Unfortunately, in certain cases this reaction seems to be irreversible.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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  • Wieland LS et al, "Elderberry for prevention and treatment of viral respiratory illnesses: a systematic review." BMC Complementary Medicine and Therapies, April 7, 2021. DOI: 10.1186/s12906-021-03283-5
  • Read SA et al, "The Role of Zinc in Antiviral Immunity." Advances in Nutrition, July 1, 2019. DOI: 10.1093/advances/nmz013
  • Hunter J et al, "Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trials." BMJ Open, Nov. 2. 2021. DOI: 10.1136/bmjopen-2020-047474
  • Lahaye C et al, "Minerals and antioxidant micronutrients levels and clinical outcome in older patients hospitalized for COVID-19 during the first wave of the pandemic." Nutrients, March 21, 2023. DOI: 10.3390/nu15061516
  • Tabatabaeizadeh S-A, "Zinc supplementation and COVID-19 mortality: a meta-analysis." European Journal of Medical Research, May 23, 2022. DOI: 10.1186/s40001-022-00694-z
  • Thomas S et al, "Effect of high-dose zinc and ascorbic acid supplementation vs usual care on symptom length and reduction among ambulatory patients with SARS-CoV-2 infection: The COVID A to Z randomized clinical trial." JAMA Network Open, Feb. 1, 2021. DOI: 10.1001/jamanetworkopen.2021.0369
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