Zinc for the Common Cold

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.

Taking Zinc to Prevent a Cold:

Q. Zinc has a reputation for fighting colds. At the very first sign of a possible cold (a funny tickle in the throat or sinuses), I start taking 15 mg zinc, four times a day. I take it with each meal and again at bedtime.

If I follow that regimen for about three days, I can usually prevent a cold from coming on. It’s important to start before the symptoms become full blown.

The whole point of taking higher doses is that zinc gives your immune system a real boost to fight the infection before it takes hold. Four times a day dosing keeps the zinc level steady in your body. I don’t stop after the first day or two, even if it feels like I’ve beat it. Symptoms can come back if it’s stopped too soon. I’ve used this for years.

A. The use of zinc lozenges to ward off a cold has a fascinating history. It began when a child being treated for cancer refused to swallow a zinc pill and instead allowed it to dissolve in her mouth. Unexpectedly, her developing cold symptoms disappeared.

Later studies suggested that zinc acetate lozenges might be used to help shorten colds (BMC Primary Care, Feb. 25, 2015).  Taking zinc multiple times a day, as you do, has been shown to reduce symptoms such as runny nose, stuffiness, sneezing, scratchy throat and cough. Trying to determine how long you should take it might be tricky. Most people stop once they feel the danger is past.

A review of research (Frontiers in Pharmacology, Feb. 1, 2022) compared the length of colds treated with zinc lozenges to those on placebo.  Bad colds that lasted two weeks or more without treatment were shortened by about eight days. Colds that lasted just two days if they weren’t treated were one day shorter.

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.

These results are consistent with those from an earlier study conducted in Canada (Canadian Medical Association Journal, July 10, 2012). The investigators reviewed 17 randomized, placebo-controlled trials with more than 2,000 volunteers. In these studies, the overall data show that zinc shortens the duration of cold symptoms by about two and a half days in adults. Children don’t appear to benefit from zinc, and most adults experience nausea or an unpleasant taste.

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 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.

Learn More:

You can learn more about zinc and other strategies in our eGuide to Colds, Coughs & the Flu.  Short-term use of zinc for the common cold is relatively safe, though it can cause GI upset. Longer term, high-dose zinc could lead to a copper deficiency.