The saying goes:  “it takes about a week to get over a cold without medication but only seven days with medication.” But this joke is now in doubt – with 3 trials showing that zinc reduces symptom duration in colds.

Researchers analysed the 3 trials involving almost 200 patients who had a cold. They found that those who took zinc acetate lozenges had colds that were around 2 to 3 days shorter on average, regardless of the initial severity of the cold. The effect of the lozenges was not modified by allergy status, smoking, age, sex or ethnic group, say the Finnish researchers.

“One study indicated that zinc lozenges might be more effective for common cold patients with allergies, but we showed that the efficacy is the same for those with and without allergies,” says lead author Dr Harri Hemila.

He says common cold patients should be encouraged to try zinc acetate lozenges not exceeding 100mg of elemental zinc per day, starting on day one of the cold.

While it is still unclear why zinc is efficacious, Dr Hemila notes the effects appear to be restricted to nasal and mouth regions, suggesting it’s a surface effect rather than zinc being absorbed and attacking the virus from the bloodstream.

As for vitamin C, Dr Hemila says it too has been shown to shown to reduce symptoms, although the effects are minimal.

In an interview on the ABC’s Health Report, he says results from a Cochrane review show that symptom reduction is around 8% in adults and 13% in children.

“There is strong evidence that Vitamin C is helpful but the question is how great is the benefit and which kind of doses should a person take. We don't have answers to those questions,” he told the ABC.  “I would be quite cautious in drawing any practical conclusions.”

Last Reviewed: 14/07/2016



Zinc acetate lozenges for treating the common cold: an individual patient data meta-analysis.