Zinc tablets may shorten the duration of a cold

It is one of medicine's most sought-after remedies: a cure for the common cold. Scientists have now found taking zinc tablets may shorten the duration of the cold – but the side-effects scarcely make it worthwhile.

Researchers, who examined 17 randomised controlled trials involving 2,100 patients, concluded high doses of zinc were more effective than low doses, but the strength of the evidence was "moderate", they say. Larger trials are needed to confirm the findings before it is possible to give medical advice. Adults have up to four colds a year on average and children up to 10.

Zinc can inhibit replication of rhinoviruses, a key cause of the common cold. But, unlike in adults, there was no apparent effect from taking zinc in children. And patients who took zinc were more likely to suffer side-effects, such as nausea and diarrhoea, than those who took nothing.

Michelle Science, of the Hospital for Sick Children, Toronto, who led the study, published in the Canadian Medical Journal, said: "Until further evidence, there is only a weak rationale for physicians to recommend it."