TUESDAY, July 20 (HealthDay News) -- Use of over-the-counter homeopathic nasal zinc gluconate gel may result in loss of the sense of smell, according to a report in the July issue of the Archives of Otolaryngology -- Head & Neck Surgery.
Terence M. Davidson, M.D., and Wendy M. Smith, M.D., of the University of California in San Diego (UCSD), studied 25 patients who presented at the UCSD Nasal Dysfunction Clinic complaining of an inability to smell (anosmia) after using homeopathic zinc gluconate gel intranasally. The researchers also reviewed the medical literature to evaluate a possible causal link using the Bradford Hill criteria for causality.
The evidence in the medical literature, including the 1 percent incidence of anosmia in 4,700 Canadian children who received the medication in the 1930s, and numerous case reports suggested a strong relation between zinc gluconate and anosmia, the researchers found. The association of zinc gluconate with anosmia has been observed at many places and times, and is temporally linked to the condition (immediate burning, loss of smell following in minutes or hours), the authors write. Further, a dose-related, cause-and-effect relationship has been plausibly suggested in research with rodents, and there are analogies with other chemicals causing anosmia.
"Protecting our patients from the potential risks of intranasal zinc medications and other homeopathic drugs, especially ones with limited proven therapeutic benefit, should be a high priority of the FDA," the authors conclude.
One study author has served as an expert witness in litigation over cases of zinc-induced anosmia.
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