In wintertime, it can feel as if everyone is sick. From passengers coughing and sneezing on the bus to kids in daycare surrounded by multiple illnesses, the so-called common cold is a virus easily introduced to the body this time of year.
True to its nickname, it’s estimated that a human being will have more common colds than any other virus in their lifetime. While adults catch on average between three to four colds a year, kids can come down with four or more every year. Between fatigue, runny nose, body aches, scratchy throat, and the occasional fever, it’s only normal for people to try to outsmart one of the 200 viruses that can cause a cold.
A typical go-to remedy is the mineral zinc, via the form of lozenges or supplements. We need zinc in our diets in order to grow and sustain our health. The mineral contributes to the growth of cells and DNA, heals damaged cells, and can support a healthy immune system. But to do this, a person only needs zinc in small amounts.
For example, it’s recommended that adult males have an intake of 11 milligrams a day; women, should have eight. Yet, for over 40 years, zinc has become a popular supplement to take as a preventative measure to strengthen a person’s immune system or even cut down the time a cold can last. Some people might even take zinc supplements to try and prevent colds altogether. But much like the rest of the supplement world in the United States, zinc is highly unregulated. Plus, is there any scientific evidence to suggest that it will help with preventing and easing colds?
“There is no concrete evidence that shows that zinc is helpful for the treatment of colds,” Dr. Barbara Bawer, primary care physician at The Ohio State University Wexner Medical Center, told Salon. “There are unfortunately not enough studies or good studies out there; of those that exist, some show it is helpful and others show it is not.”
Indeed, a recent Cochrane review published in May 2024, of 34 published studies on both adults and children, found that taking zinc may help reduce the duration of common cold symptoms by about two days. Cochrane reviews are incredibly rigorous and considered the highest standard in medical science. However, the publication's systematic review found that the evidence for zinc was “not conclusive.”
“When zinc is used for cold treatment, there may be a reduction in the mean duration of the cold in days although it is uncertain whether there is a reduction in the risk of having an ongoing cold at the end of follow‐up,” the researchers wrote.
The review also states that potential benefits “must be balanced against side effects.” Common side effects of zinc reported in the trials the studies reviewed included issues with bowel movements, nausea and an unpleasant taste. There have even been reports of zinc-induced anosmia syndrome, meaning a loss of smell, from zinc nasal sprays.
Since the 1980s, zinc products have been marketed as treatments for the common cold. That’s when a published study, which compared people with a cold taking zinc lozenges to those not taking zinc lozenges, found that the mineral shortened the time people felt sick from their colds by up to seven days. But since then there have been dozens of other studies trying to suss out the benefits of taking zinc to help a cold.
“Even those studies that show improvement only show that there might be a decrease in the number of days you have symptoms but does not resolve the severity of symptoms,” Bawer said. “We do not, as primary care physicians, routinely recommend zinc given the poor evidence out there.”
William Schaffner, a professor of infectious disease at Vanderbilt University Medical Center, told Salon before the 1980s, zinc was seen as a “folk medicine.” He said there is some truth that it can help possibly shorten the duration of a cold, but it is a “modest effect.”
“And obviously, you will have to take zinc for a long period of time,” Schaffner said. “Most people are not so keen on that, because it can leave a metallic taste in your mouth.”
On the topic of side effects, Bawer added there are concerns about zinc causing some antibiotics or water pills to be “less effective” when taken together. “If taken in too high doses can also lead to a decrease in immune function, copper deficiency, and change your iron functioning,” Bawer added.
Then there’s the issue that people might not know what’s actually in their zinc supplements. Indeed, the U.S. Food and Drug Administration considers zinc supplements to be dietary supplements, there is no way for the quality to be ensured or for consumers to know what else the supplements contain.
“Unfortunately, zinc is not highly regulated just like most supplements,” Bawer said. “The FDA does not regulate the effectiveness or safety of supplements or even labeling of the supplement.”
When it comes to dietary supplements, the FDA only requires "reasonable assurance" that dietary supplements do not pose "a significant or unreasonable risk of illness or injury." Several studies have shown as many as 70% of supplement labels do not correspond to what is inside.
Still, some people may turn to zinc for cold prevention. In that case, Bawer says the typical dosing is up to 40mg per day which can be divided into two or three doses over the day.
But more importantly, there are other ways to prevent colds, Schaffner emphasized.
“The most important thing you can do is try to avoid people who are coughing and sneezing, which is easy to say, but difficult to do in the respiratory virus season,” Schaffner said. Of course, wearing a mask could help with that, especially if you're the one sick, so as to prevent others from getting infected. Masks aren't just useful for preventing COVID-19. “The other thing is to do good hand hygiene.”
In other words, cold prevention might have more to do with your behavior and less to do with what you put inside your body, perhaps as simple as washing your hands.
