Sometimes, it’s hard to smell a rat, and if University of California, San Diego professor Terence M. Davidson, MD is correct, zinc-based cold remedies can make it even harder. Using a statistical method that shows a cause-and-effect relationship between exposure to a substance and the development of a disease, Davidson’s study showed that use of certain cold medicines containing zinc can lead to hyposmia (reduced ability to smell) and anosmia (the loss of the ability to smell).
The FDA jumped on this issue last year when it received 130 reports of loss of smell from users of three Zicam products — Zicam Cold Remedy Nasal Gel, Zicam Cold Remedy Swabs, and Zicam Cold Remedy Swabs for kids. The FDA advised consumers to stop using these products and the manufacturer, Matrixx Initiatives, voluntarily pulled the products from the shelves while making clear that it “vigorously disagrees with the FDA’s allegations.”
Davidson’s research team also questioned whether zinc gluconate, which is the active ingredient in the offending products, actually prevents colds or shortens their duration. “Given that they do absolutely no good for colds,” he said, “and given that there is potential for harm, I see no point in putting any zinc gluconate products in the nose.”
Not surprisingly, Matrixx Initiatives takes issue with the study conclusions. The company says that when people lose their ability to smell, respiratory infections and sinus problems are to blame. In fact, in 10 lawsuits brought against the company, the judges found little to no scientific evidence that zinc products diminished smell. In at least one case, the judge rejected Dr. Davidson as an expert witness, calling his conclusions seriously flawed. It’s interesting to note that Dr. Davidson’s statistical research “proving” the problems with zinc included only 25 people. Meanwhile, opinion in the medical community remains split. For instance, Neurologist Robert I. Henkin, MD, of the Taste and Smell Clinic in Washington, D.C., says, “The most frequent cause of smell loss is the common cold. The role these zinc-based products play in initiating or exacerbating this condition remains very difficult to ascertain.”
On the other hand, 340 Zicam users, after ostensibly losing their sense of smell, brought suit against Matrixx Initiatives in 2006 and won their case. Matrixx settled for $12 million. At the time, the company issued a statement saying, “The decision by Matrixx to settle some lawsuits was a business and economic decision. It was not based on any perception that the claims are legitimate.”
Nevertheless, over the years, 10 other suits have been brought against the company from users who also claimed diminished or lost sense of smell. CEO Hemelt makes a point of the fact that, as stated above, none of the judges in those ten suits found more than scant evidence that zinc is to blame. But the fact that so many users encountered trouble enough to bother filing suits does make the zinc formula seem a little less friendly.
Dr. Davidson claims that his patients and others who suffered a loss of smell when using Zicam products first experienced an extremely painful sensation of burning in the nose, after which they could no longer smell. Hemelt responds that his company’s independent tests show that such burning resulted equally from the use of the spray and placebos containing no zinc.
Smell aside, according to WebMD, zinc gets mixed reviews, at best, for its effectiveness as a cold remedy. On top of that, potential side effects include upset stomach, mouth irritation, metallic taste, and loss of smell. A 2006 study concluded that zinc really didn’t help colds. The report read, “We contend that it is unethical to introduce any potentially permanent anosmia-inducing agent such as zinc or other heavy metals into the interior of the nose in a manner that could result in contact with the olfactory region to treat a temporary discomfort such as a common cold or allergy.” On the plus side of the ledger, a study reported by Reuters in 2008 showed that zinc acetate lozenges shortened the duration of colds in study subjects. Led by Dr. Ananda S. Prasad from Wayne State University School of Medicine, Detroit, the study looked at the impact of the lozenges on 50 volunteers with colds. All of the volunteers had cold symptoms for less than 24 hours before taking part in the study. Among the group who received the lozenges, 56 percent were completely “cold free” within four days, as compared to an average of seven days for the placebo group. Also, it’s important to note that the FDA warning did not include zinc lozenges, tablets, or dietary zinc. The loss-of-smell issue appears to apply only to zinc gluconate applied topically.
Perhaps the position taken by the U.S. National Institutes of Health (NIH) makes the most sense. (Did I just say that?) On its website, the NIH Office of Dietary Supplements says, “The effect of zinc treatment on the severity or duration of cold symptoms is controversial. Researchers have hypothesized that zinc directly inhibits rhinovirus binding and replication in the nasal mucosa and suppresses inflammation. However, no data are available to support this hypothesis.”
Given the side effects that have been reported for the topical use of zinc, you might do better to avoid the whole mess in the first place and protect yourself by wearing a surgical mask 24/7 and making a point of never shaking anyone’s hand or touching any doorknobs or phones. On the other hand, you could just use a powerful immune builder and a good quality natural antipathogenic formula that includes such ingredients as garlic, oil of oregano, olive leaf extract, and yes…zinc, but internally — not topically.