Zinc lozenges are sometimes taken to ward off symptoms of the common cold, but they might cause serious neurological damage if overused. Although the Office of Dietary Supplements, a service of the National Institutes of Health, says research supports zinc's role in boosting the immune system, a study of denture creams with high zinc content revealed that too much of the mineral can indirectly cause severe neurological damage.
Denture Cream
In a study published in the June 4, 2008, issue of "Neurology," researchers led by neurologist Dr. Sharon Nations of the University of Texas Southwestern Medical Center examined four patients with serious neurological problems and concluded their conditions were a result of the high levels of zinc contained in their denture creams. An article in "The New York Times" says that reaction in the scientific community has been mixed, with some agreeing with the report's conclusion and others feeling more research is needed. If users were getting too much zinc from denture cream, the same danger may exist when taking zinc lozenges.
Mechanism
Technically, excess zinc does not cause neurological damage. However, ingesting too much zinc from lozenges or other sources over a long period of time causes a condition called hypocupremia, which is a low level of copper in the bloodstream. A copper deficiency can lead to permanent neurological damage. The article in "The New York Times" highlights two men who had been using large amounts of denture cream and now have nerve damage so severe both were unable to move around without walkers.
Other Dangers
The Office of Dietary Supplements says zinc can be dangerous if taken in large amounts. The safe daily levels range from 4 to 5 milligrams for infants to 40 milligrams for adults. Doses in excess of these levels can cause nausea, vomiting and headaches. Long-term high doses of zinc can lead to lowered immunity and low HDL, or "good", cholesterol in addition to the aforementioned copper deficiency. Zinc lozenges may also interfere with some antibiotics, rheumatoid arthritis drugs, or diuretics.
Warnings
Most Americans get plenty of zinc from their diets, according to the ODS. Some groups, such as people with digestive disorders, vegetarians, alcoholics and older breast-fed infants, may not get enough zinc and may need a supplement. Before using zinc lozenges, speak with your doctor about how it might affect any medical conditions you have or might interact with any of your medications. If you are taking zinc to fight cold symptoms, zinc pills have not been shown to have the cold-fighting effects of zinc lozenges or syrups.
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