You may have heard you should take zinc for a cold. Is there any scientific evidence that zinc gets rid of colds?
Well, first, the idea isn't that by taking a zinc lozenge, your cold will, poof, disappear. However, some studies do indicate that zinc will lessen the severity and the duration of a cold.
There is quite a bit of disagreement as to whether zinc works or not. Studies of zinc treatment are almost split down the middle and all of them have been criticized for possible flaws. Studies that find zinc useless may have used inadequate forms of zinc that are inactive in the human body. Studies that favor zinc may have used a placebo that didn't taste like zinc. The problem is that if participants could tell they were or were not getting the real thing, then their resulting psychological states may have affected their rate of recovery.
Putting all these possible flaws aside for a moment, the best known of the pro-zinc studies showed that people who within a day of the onset of a cold began taking zinc lozenges every two hours while they were awake recovered three days faster than the placebo group.
The most common side effects are dry mouth and constipation. Some people experience nausea. Also, because this regimen of zinc every two hours adds up to be about five times the RDA of 15 milligrams, researchers suggest taking zinc lozenges for no more than three days at a time.