The question
Can zinc cure a cold?
The science
Everyone loves a good cold remedy — vitamins, homemade concoctions, nasal irrigation systems. And zinc, a mineral, is a popular one, sold over the counter as lozenges, quick-dissolve tablets and nasal sprays.
While there’s no conclusive evidence that zinc can prevent a cold, there is research suggesting it might help shave a little time off the duration of a cold, which usually runs for seven to 10 days.
“If you’re trying to get better, say, before you go see your brand-new grandchild or because you have a big presentation coming up at work, it may cut a day or two off your cold but you might still have persistent symptoms,” said Rebecca Andrews, a professor at the University of Connecticut School of Medicine and chair of the Board of Regents for the American College of Physicians.
Scientists have hypothesized that zinc may prevent rhinoviruses — which are common viruses that cause about 50 percent of colds — from infecting our cells, said Roy Gulick, the chief of the Division of Infectious Diseases at Weill Cornell Medicine and attending physician at New York Presbyterian Hospital in New York City.
The mineral also enhances immune function and responses to infection, among other things, he said.
In a 2024 Cochrane review, researchers analyzed 34 trials using zinc to prevent and treat colds. The authors found little to no evidence that zinc, when taken proactively, can prevent a cold or reduce the number of colds a person gets.
For people who already have a cold, the reviewers found some evidence that zinc might shorten the duration of symptoms by about two days compared with a placebo. However, they also found that zinc was associated with mild side effects such as nasal and oral irritation, problems with taste, stomach pain, constipation, diarrhea and vomiting, among others.
Outside those trials, some people who use certain zinc nasal products have reported a loss of smell. It prompted the Food and Drug Administration to issue a public health advisory in 2009, warning people about the link between some zinc nasal products and long-lasting or permanent loss of smell.
Our bodies don’t produce zinc, which we need for proper immune system and metabolism functioning and wound healing. Adult women should get 8 milligrams of zinc from their diets each day and men 11 mg, according to federal health authorities. Zinc-rich foods include meat, fish and seafood such as oysters.
The optimal zinc dose for the treatment of colds is uncertain because researchers conduct studies in different ways, and test different forms of zinc and different doses. However, a number of studies on zinc as cold treatments use doses of 80 mg or more per day. Many over-the-counter zinc lozenges are supposed to be taken every few hours, which amounts to about 80 mg.
But Andrews said that if you exceed 50 mg of zinc per day, you increase your likelihood of side effects. And don’t use it to prevent a cold — only to treat an ongoing one, she said.
“When you supplement, you’re going to get a lot more than what you need in your diet, which is more likely to cause stomach upset and send you either into my office or an urgent care, where you might get treated for something that you don’t have because the symptom could be from the zinc,” she said.
What else you should know
Before taking zinc, speak with your health care provider, as the mineral can interact with some medications. For instance, high zinc intake may make certain chemotherapy drugs less effective, Andrews said.
If you want to try zinc to treat a cold, consider these suggestions:
- Don’t use zinc supplements as a preventive, only a treatment. Because there’s little to no evidence that zinc can prevent a cold and it’s associated with a number of side effects, use it only when you have symptoms of a cold.
- Try lozenges, but in moderation. Most studies have evaluated the effectiveness of zinc lozenges over other formulations, probably because they are easy to take and may help ease sore throats, a common symptom of a cold, Andrews said. But don’t overdo it. If you exceed 50 mg daily, you increase your risk of stomach upset and other side effects, she said.
- Don’t take zinc with certain foods. High-fiber foods, legumes and grains, foods rich in calcium and iron, and excessive alcohol, among other things, can reduce zinc absorption.
- Zinc aside, build up your immune system. Eating a healthy, well-balanced diet, drinking plenty of water and getting enough sleep are key for ensuring your immune system “is top-notch from a cold-fighting perspective,” Andrews said.
The bottom line
While zinc is unlikely to prevent a cold, it may help reduce the duration of a cold by a day or two. But potential benefits of zinc, particularly at higher levels, may be offset by adverse reactions, including irritation in the nose and mouth, an upset stomach and other side effects.
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