Tues. Feb. 15, 2011 — Taking zinc at the first sign of a cold will mean getting over the cold sooner, the benefits come at the expense of some side effects, a Cochrane review showed.
Moreover, people who took zinc were less likely to take antibiotics — which are useless against colds since they are caused by a virus — and missed less days of work or school, according to Dr. Meenu Singh, and Dr. Rashmi Das, of the Post Graduate Institute of Medical Education and Research in Chandigarh, India.
The Zinc Debate Continues
“Given that some formulations (especially lozenges) produced side effects and not all formulations may be effective, the use of zinc to treat common cold symptoms is presently advised with caution,” Singh and Das wrote.
Dr. William Schaffner, chair of the department of preventive medicine at Vanderbilt University, said in an e-mail to ABC News and MedPage Today that the review consolidates what is known about zinc for the common cold
“The good news is that zinc has some benefit,” he wrote. “If taken very promptly, zinc seems to reduce the duration of a cold somewhat. Also, taking zinc as a preventive measure also seems to work somewhat. Neither effect is large, however.
“The bad news is there are side effects to zinc,” Schaffner wrote.
“Also, there are no standard zinc formulations. We still don’t know what the best dosage is.”
He said that he does not recommend zinc, but will describe the possible benefits and side effects to interested patients.
Schaffner added that “the best treatment for a cold remains fluid, decongestants, and time. Avoid antibiotics!”
In the U.S., the common cold results in 75 to 100 million physician visits a year, accounting for an estimated $7.7 billion annually.
Americans spend another $2.9 billion on over-the-counter remedies and $400 million on prescription medications for symptom relief.
Try a Home Remedy
In addition, colds are responsible for millions of days lost from school and work, with cold-related work losses exceeding $20 billion a year.
Thus, Singh and Das wrote, “any medication that is only partially effective in the treatment and prevention of the common cold could markedly reduce morbidity and economic losses due to this illness.”
Findings from trials evaluating zinc for the treatment and prevention of the common cold have yielded mixed results. So the researchers examined randomized, double-blind, placebo-controlled trials published since 1984 evaluating zinc — in lozenge, tablet, or syrup form — for treatment (lasting at least five days) or prevention (with participants taking the supplement for at least five months).
They identified 13 treatment trials including 966 participants and two prevention trials including 394 participants. All of the trials were conducted in high-income countries.
Overall, zinc had beneficial effects on the duration and severity of cold symptoms.
A significantly smaller proportion of patients in the zinc group compared with the placebo group were still symptomatic after seven days of treatment — 37 percent versus 56 percent.
In the prevention trials, the rate of the common cold was reduced with zinc from 62 percent to 38 percent.
The average length of school absence was reduced by an average of 0.37 days, and fewer patients taking zinc received a prescription for antibiotics — 13 percent versus 33 percent.
The researchers described the quality of the evidence as moderate (indicating that further research may change the estimate) for the analyses of duration, severity, and incidence, and as low or very low for the other outcomes.
Although zinc appears to be useful in treating or preventing the common cold, the mechanisms underlying the benefits remain unclear, according to Singh and Das.
Possibilities include an interaction of zinc with the host’s immune function, direct inhibition of viral replication, and a blocking of receptors on the nasal epithelium occupied by rhinoviruses during a cold.
But even with the potential benefits, the researchers wrote, “the higher incidence of side effects in zinc-treated participants will most likely limit the usefulness of zinc in the treatment of cold symptoms.”
This article was developed in collaboration with ABC News