Taking zinc when a person is suffering from sniffles could reduce cold symptoms by a couple of days, but it’s not a sure thing. Researchers looked at more than 30 studies that examined people who consumed zinc as either a preventative measure to ward off colds or as a treatment for the symptoms.
Authors say that there is no evidence that Zinc is useful for cold prevention but a review of eight studies of nearly 1,000 participants for zinc as a treatment for a cold symptom found “low certainty” evidence the nutrient could shorten the duration by a couple of days. The theory behind zinc as a cold treatment is that it might interrupt the replication of the cold virus, similar to how an antiviral drug works.
However, while zinc is widely marketed in a variety of forms with claims to help treat or prevent colds from pills to sprays to syrups and lozenges there’s no consensus on whether zinc is effective or if one form is better than another.
The timing of zinc supplementation about the onset of cold symptoms may impact its effectiveness, adding complexity to study designs. Variations in individuals’ immune responses and genetic factors can influence their reactions to treatments, contributing to variability in study findings. However, experts say this review should help point the way toward better future studies on zinc to determine its efficacy once and for all.
There is more research before we can be confident in its effects. Future studies should adopt standardized methods for administering and reporting treatments and defining and reporting outcomes. Additional studies focusing on the most promising types and doses of zinc products and using appropriate statistical methods to assess outcomes that are important to patients will enable us to understand whether zinc may have a place in the treatment of the common cold. Then, there’s the question of even defining a “cold” in the context of a clinical trial.
There is no consistency in the definition of who has a common cold. It is certainly possible that zinc may at times improve the course of a viral cold illness, but its potential benefits must be weighed against its potential risks. Zinc can be a stomach irritant causing nausea, abdominal pain, and sometimes vomiting. The chemical similarity between zinc and copper can lead to zinc blocking copper absorption, resulting in copper deficiency. Copper deficiency may manifest as neuropathy, anemia or immune dysfunction. The federal Food and Drug Administration has also warned against the use of zinc nasal sprays due to a risk of decrease or loss of sense of smell.
If a patient can start taking zinc at the onset of cold symptoms without experiencing an upset stomach, it’s likely safe for them to use. To ensure safety, patients should consult with their healthcare provider before starting any new supplement regimen, as supplements can potentially have side effects and interact with medications.
