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 While some past research also suggested that zinc lozenges work
better for people with allergies, the new review found similar
benefits for people without allergies.
In common colds, the virus may grow in the pharyngeal, or throat,
region, which is why using lozenges may work better than swallowing
pills, the study team notes in British Journal of Clinical
Pharmacology.
“Ordinary tablets that enter directly into the stomach, without
releasing zinc in the pharyngeal region, are not effective,” said
lead author Dr. Harri Hemila of the University of Helsinki in
Finland.
Since clinical studies using low-dose zinc lozenges had found no
effect on common colds, Hemila and his team looked only at trials
that used lozenges delivering a total of 75 milligrams of zinc or
more per day.
They found three trials comparing these high-dose zinc lozenges
against a placebo in common cold sufferers who were randomly
assigned to one treatment or the other. One trial also looked at
differences in results for people with and without allergies.
The trials had a total of 199 participants, who were were mostly
female and between 20 and 50 years old. One third had allergies,
including allergies to grasses, trees and pets.
Participants were instructed to have a lozenge every two to three
hours and the lozenges took about 15 to 30 minutes to dissolve.
Overall, the average dose of zinc was between 80 and 92 mg of zinc
per day.
The review found that patients who used zinc lozenges experienced
colds that were 2.94 days shorter, compared with the seven-day
average of colds in the comparison group.
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.
“This is a very important subject to study because the common cold
is a very common problem and it leads to loss of work as well as
disability because people are not able to focus,” said Dr. Meenu
Singh, a professor of pediatrics at the Postgraduate Institute of
Medical Education and Research in Chandigarh, India.
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Singh, who was not involved in the study, told Reuters Health by
email that while these results are promising, there are some side
effects of zinc that need to be explored before high doses of zinc
are available over the counter.
For example, in previous studies, using zinc as an inhalant caused
people to temporarily lose their sense of smell, Singh said, noting
that lozenges could dampen taste as well.
Some patients also complain that the lozenges leave a metallic taste
in the mouth, though the participants in trials reviewed did not
find this to be a problem, the study team points out.
“There is information now available that zinc in a higher dose could
reduce your cold by a certain duration, but there is an added
discomfort of taking lozenges,” Singh said by email. The tablets are
large and need to be taken continually throughout the cold to be
effective, he said.
Hemila cautioned that common cold patients should look for lozenges
that do not contain citric acid, which can prevent the release of
zinc into the body.
“Common cold patients should try zinc lozenges with doses about 80
to 100 milligrams per day very soon after the onset of the common
cold,” Hemila advised, adding that the lozenges can be used for one
to two weeks of treatment.
SOURCE: bit.ly/29ExGiN British Journal of Clinical Pharmacology,
online July 5, 2016.
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