The common cold can be beaten by taking zinc supplements in high doses, research has suggested.
The effects of zinc lozenges of different strengths were analysed by scientists who assessed the results of 13 studies.
Daily doses of zinc acetate higher than 75 milligrams were found to shorten colds by an average of 42%, according to data from three studies.
However, five studies involving zinc doses lower than 75mg showed no benefit.
Other studies showed that the duration of colds was reduced by 20% when other types of zinc salt were given at doses greater than 75mg.
The study, published in the Open Respiratory Medicine Journal, found no evidence that the lozenges caused any long term harm.
The authors said the poor evidence surrounding the use of zinc to treat the common cold may be due to studies using different doses.
They wrote: “Since a large proportion of trial participants have remained without adverse effects, zinc lozenges might be useful for them as a treatment option for the common cold.”