Forget cough lolly drops that taste like honey and berries -- the only lozenge shown to cut down the time of a common cold has a really repulsive flavour.
A salt called zinc acetate is the only ingredient shown to cut down the length of a cold by an average of two to three days in two different randomised control tests.
In each test, those who had lozenges containing zinc acetate cut down the duration of their cold by 2.7 days and 2.9 days and it worked regardless of age, smoker status and susceptibility to allergies.
It's not entirely known how the zinc acetate shortens a cold, but its curative properties were accidentally discovered in 1985 when a three-year-old girl being treated for leukemia did not swallow her zinc tablet, and her cold cleared up faster than usual.
Before you head out to buy zinc lozenges, researchers said most zinc-based products were poorly made and ineffective.
"It appears that the majority of zinc lozenges on the market have either doses of zinc which are too low or contain substances that bind zinc, such as citric acid," the report said.
"Therefore, the findings of this analysis should not be directly generalized to the wide variety of zinc lozenge formulations on the market."
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How to buy the right zinc lozenge
The ingredient 'zinc acetate' is more effective than 'zinc gluconate'.
A dose of more than 75mg a day was more effective than under 75mg.
Avoid products that also include flavours like citric acid as they bind tot he zinc, making it less effective.