Short-Term Zinc Therapy May Reduce Duration of Common Cold High doses of zinc may provide relief to people who suffer from the annoying symptoms of a cold including cough, sore throat and stuffy nose, researchers report. But consuming high doses of the mineral for more than 3 days can be dangerous, investigators warn. Too much zinc can lead to a deficiency of copper, a rare condition that can disrupt normal growth and metabolism. "Zinc therapy for the common cold should be limited," according to Dr. Ananda S. Prasad from Wayne State University in Detroit, Michigan, and colleagues. "We recommend that if a person does not show clear evidence of improvement after 3 days of zinc treatment, he or she should be investigated for other respiratory tract disorders," the authors conclude in the August 15th issue of the Annals of Internal Medicine. The editors of the journal point out that the study was funded by a foundation related to the company holding the patent for zinc lozenges. While results show that zinc acetate lozenges appear to reduce the duration of cold symptoms, more research is needed to describe the mechanism at work, according to the editorial. Some researchers suggest that zinc may help to reduce cytokines, immune system proteins that help to drive inflammation, but the current investigation found no significant differences in levels of cytokines between the two groups, the editors add. To investigate the role of zinc in treating cold symptoms, the researchers instructed 50 people with a cold to take a zinc lozenge containing 12.8 milligrams (mg) of zinc acetate, or a placebo (inactive pill), every 2 to 3 hours for as long as symptoms persisted. Each day, patients rated the severity of their symptoms including sore throat, runny nose, congestion, sneezing, coughing, scratchy throat, hoarseness, muscle ache, headache and fever. Overall, individuals who took zinc suffered cold symptoms for fewer days than those taking a placebo. The zinc group reported symptoms for an average of 4.5 days and those in the placebo group for about 8 days. Runny nose and cough appeared to respond best to the mineral. Coughing lasted about 6 days in the group of patients taking a placebo compared with 3 days in the group taking zinc. Side effects of zinc lozenges included dry mouth and constipation but the mineral did not appear to lead to nausea, vomiting, diarrhea or stomach cramps, the findings suggest. "Treatment with zinc acetate lozenges was associated with reduction in the duration and severity of symptoms of the common cold," Prasad and colleagues conclude. SOURCE: Annals of Internal Medicine 2000;133:245-252, 302. Richard T Herrick,MD herrickclinic@mindspring.com www.herrickclinic.com