AUBREY: But here's the caveat, and it's a big one - in the U.S., many zinc lozenges don't contain enough zinc, and many have a bunch of ingredients that can undercut the effectiveness.

When a zinc acetate formulation is taken in a high enough dose and started early in the onset of a cold, it’s likely to be effective, said Dr. Ananda Prasad, an expert on zinc at Wayne State ...

The effect of the zinc lozenges was not altered by a person’s allergies, smoking or how severe the cold was. The results were also similar across age, sex and ethnic groups.

Bad taste has been a common complaint of zinc lozenges. In the study carried out by Dr. Hemilä and colleagues, 37% of zinc participants did not complain of any adverse effects.

Researchers gave 25 people zinc acetate dihydrate lozenges within 24 hours of the onset of a cold; 23 others received an inert substitute. Both lozenges tasted of peppermint.

The data curve (shown on the right) suggests that zinc may be even more beneficial than they previously estimated. By Day 5, 70% of people taking zinc lozenges had recovered from the common cold, ...

AUBREY: But here's the caveat, and it's a big one - in the U.S., many zinc lozenges don't contain enough zinc, and many have a bunch of ingredients that can undercut the effectiveness.