MONDAY, July 19 (HealthDay News) -- To try and lessen the effects of the common cold, many people have turned to homeopathic remedies, including products containing zinc.
However, a new analysis suggests that nasal gels containing zinc and nasal swabs with zinc have most likely caused a loss of smell in some users.
"In my practice, we started seeing people using the zinc nasal gel. They squirted it in, took a deep sniff and then had an incredibly intense burning sensation that lasted for several hours. When these people recovered, they found they had no sense of smell," explained study author Dr. Terence Davidson, director of the University of California at San Diego Nasal Dysfunction Clinic.
The loss of smell is called anosmia, and Davidson said that people might not appreciate how significant it can be. "Most of us take our sense of smell for granted. But, people need to take a moment to realize how important smell is. It helps us avoid dangers when we smell smoke or gas or rotten, spoiled food and it brings us incredible pleasure -- think about the smell of our homes, loved ones, food, coffee. In fact, 90 percent of our appreciation for food comes from our sense of smell," he said.
Davidson said that some of the people affected by the zinc-induced anosmia filed lawsuits against the manufacturers of these products. However, there are no randomized, controlled clinical trials that conclude a loss of smell is one of the possible outcomes from using these products, making it harder to prove cause-and-effect.
Since it would be impossible, as well as unethical, to try to conduct such a study now, Davidson and his colleague, Dr. Wendy Smith, applied the "Bradford Hill Criteria" to 25 patients they had seen for the sudden loss of smell after using a zinc gel product.
The Bradford Hill Criteria were developed in 1965 by a statistician who wanted to establish a cau
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