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Can zinc shorten the duration of the common cold?
Last reviewed: 02.07.2025
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The review included more than 30 studies that looked at people taking zinc as a cold preventative or as a treatment for cold symptoms.
In reviewing these studies, the review authors said they found no evidence that zinc is useful for preventing colds, but a review of eight studies involving nearly 1,000 participants on the use of zinc as a treatment for cold symptoms found "low-certainty evidence" that the element can shorten the duration of a cold by a couple of days.
Zinc and the common cold
The theory behind using zinc to treat colds is that it can interrupt the replication of the cold virus, similar to the action of an antiviral drug.
However, while zinc is widely promoted in various forms with claims of helping treat or prevent colds—from tablets to sprays, syrups, and lozenges—there is no consensus on its effectiveness or which form is better than another.
"The timing of zinc supplementation in relation to the onset of cold symptoms may influence its effectiveness, adding complexity to study design," said Dr. Monica Amin, PharmD, a pharmacist at Marley Drug and Medicure, who was not involved in the study.
“Differences in immune responses and genetic factors among individuals can influence their response to treatment, contributing to the variability in study results,” Amin told Medical News Today. “These factors combined make it difficult to determine whether zinc is an effective treatment for the common cold.”
Still, experts say this review should help point the way to better future studies of zinc to definitively determine its effectiveness.
“The evidence on zinc is far from conclusive: We need more research before we can be confident in its effects,” said Dr. Susan Wieland of the University of Maryland School of Medicine and senior author of the review, in a press release. “Future studies should adopt standardized methods for administering and reporting treatments, as well as defining and reporting outcomes. Additional research focusing on the most promising types and doses of zinc products and using appropriate statistical methods to assess patient-important outcomes will allow us to understand whether zinc may have a place in cold treatment.”
Then there is the question of even how to define “the common cold” in the context of a clinical trial.
“There is no uniformity in defining who has a cold. And even people who have classic cold symptoms with fever, runny nose and sore throat could be infected with one of many viruses: adenovirus, rhinovirus, metapneumovirus, influenza, RSV or even COVID,” said Dr. David Cutler, a family medicine physician at Providence Saint John’s Medical Center in California who was not involved in the study.
"So without knowing what we're treating and including patients with different diseases, it's difficult to conclude that a particular treatment improves a particular disease," Cutler said.
Should you take zinc when you have a cold?
So the decision about whether to take a supplement with a nutrient that may or may not help fight a cold is ultimately up to the individual, but experts say there are some factors to consider, including side effects.
“It’s possible that zinc can sometimes improve the course of a viral cold, but its potential benefits must be weighed against its potential risks,” Cutler said. “Zinc can irritate the stomach, causing nausea, abdominal pain, and sometimes vomiting. Chemical similarities between zinc and copper may cause zinc to block copper absorption, leading to copper deficiency. Copper deficiency can manifest as neuropathy, anemia, or impaired immune function.”
Additionally, the Food and Drug Administration has also warned about the risk of using zinc nasal sprays due to the risk of decreased or lost sense of smell.
“If a patient can start taking zinc at the first sign of a cold without developing stomach upset, it is likely safe for them,” Amin said. “To be safe, patients should consult with their healthcare provider before starting any new supplement program, as supplements can potentially cause side effects and interact with medications.”