DENVER -- The makers of the nationally advertised cold remedy Zicam now admit they don't know if their nasal gel could cause loss of smell.

The stunning information came after a 7NEWS investigation found that some consumers who have used Zicam report the loss of smell.

The company that makes Zicam (pictured, left), Matrix Initiatives, first told us its studies showed the product safe, but it will now begin animal and human testing to determine whether its zinc compound could be harmful when sprayed in the nose, causing some to lose their sense of smell.

These studies come after our investigative report aired both on '7NEWS' and ABC's 'Good Morning America.' Those reports prompted dozens of complaints to the U.S. Food and Drug Administration, which is now investigating.

In turn, the company is taking action.

Doctors at the University of Colorado Taste and Smell Clinic have an increasing number of patients who say they lost their sense of smell after using Zicam intranasal gel, which contains zinc gluconate.

Dr. Bruce Jafek has been documenting the cases from around the country, and there have been several lawsuits in at least five states. All along, Matrixx Initiatives, the maker of Zicam, said the product was safe. But now it admits there are no studies dealing with issue.

In a filing to the Securities and Exchange Commission on issues affecting stockholders, Matrixx now discloses:

"There is insufficient evidence at this time to determine if zinc gluconate, when used as recommended, affects a person's ability to smell."

What's more, after our initial investigation, dozens of consumers have filed complaints with the Food and Drug Administration.

In response, the company formed a medical advisory panel in February.

It says it will now conduct: "...animal and human studies to further characterize these post-marketing complaints." Study findings are expected to be available in 12 months.

"It seems to me that those studies should have been done before they put the product on the market," said Jafek.

He is concerned about consumers who may be at risk right now because Matrixx will leave Zicam nasal gel on the shelf until its studies are completed.

"It would seem that it would either be reasonable to remove the product from the market pending the additional study recommended by the scientific panel or at least put on a warning label so people can be aware of this problem," said Jafek. "If you want to use this product to possibly shorten duration or severity of your cold, do so but be aware that it may cause a loss of smell."

Zicam makes many products, including lozenges. These are not at issue -- only the nasal spray that contains zinc gluconate. A representative for the company responded to our story and said that Matrixx believes the product is safe and does not cause loss of smell, even though the company admits there are no studies to prove it. Even so, the company says it will not remove the nasal spray from the shelves and has no plans to put a caution label on it.

A company representative says consumers can make their own decision until the studies are finished.