Zinc For Colds...Jury Still Out!

Zinc has been shown, in preliminary studies, to inhibit the reproduction of viruses and possibly promote the production of the virus-fighter interferon.

To determine the effectiveness of zinc lozenges as treatment for the common cold, Sherif B. Mossad, M.D. and colleagues studied 100 adult patients at the Cleveland Clinic. The results of this study were published two years ago and reviewed by MedicineNet's NEWS team in an article published July 26, 1996 (see MedicineNet Doctors' Views Archives).

The results of this initial Cleveland Clinic study, published in the Annals of Internal Medicine (1996;125:81- 88), showed a significantly shorter duration of symptoms (4.4 days vs. 7.6 days) in patients taking the zinc lozenges compared to those who were given placebo.

At the time, MedicineNet's editors commented that these promising results needed to be confirmed by additional studies before we could recommend to patients with the common cold that they take zinc. Nevertheless, sales of over-the-counter zinc products, particularly zinc lozenges, skyrocketed during the past two years.

A new study published in the June 24, 1998 issue of The Journal of The American Medical Association (JAMA) by a team led by Dr. Michael L. Macknin, one of the initial researchers at the Cleveland Clinic, indicates that the zinc lozenges are not effective against cold symptoms in children and teenagers!

After evaluating the effects of zinc lozenges on the cold symptoms of 249 students in grades 1 through 12, the authors commented that "The discrepant results between these studies in adults and the current study in children may be explained by the different dosages or flavoring of the formulation, the ages of the subjects, the time of year when the studies were performed (ie, the viruses involved may have been different) or chance differences between the placebo and zinc groups."

The JAMA authors concluded that "Further studies with virologic testing are needed to clarify what role, if any, zinc may play in treating cold symptoms. "

In the eyes (and noses) of MedicineNet's editors, the jury is still out as to whether or not zinc preparations are beneficial in the treatment of the common cold. Aaaaachooooo!

Source: . Macknin ML, Piedmonte M, Calendine C, Janosky J, Wald E: Zinc Gluconate Lozenges for Treating the Common Cold in Children. A Randomized Controlled Trial. JAMA 1998;279:1962-1967.