He was like millions of other consumers who sometimes take vitamins or echinacea, hoping to build up his immunity or ward off a cold. He figured alternative remedies were as safe as a spoonful of honey.

But that notion washed away with one squirt of a homeopathic cold gel.

David Richardson, of Greensboro, N.C., is one of hundreds of patients across the country who have lodged complaints about Zicam Cold Remedy, saying it destroyed their sense of smell.

"It's like watching a sunset in black and white. The things that you take for granted, not only smelling fresh-cut grass or bread in the oven ... you miss those parts of your life," he says. "There's not a day that goes by that you're not reminded of it."

The U.S. Food and Drug Administration says that people who can't smell may also miss danger signs in their daily lives like smoke or gas. It moved to force three Zicam products - Zicam Cold Remedy Nasal Gel, Nasal Swabs and discontinued Swabs in Kids' Size - off the market Tuesday and told consumers not to take them anymore.

Zicam belongs to an under-the-radar but legal sector of the drug industry called homeopathic remedies. They hold a unique legal status: They are mainly sold without prescription as legal drugs claiming to treat specific ailments, yet they are not routinely reviewed for safety or benefit by the FDA. The agency rarely acts unless safety questions arise after marketing.

Zicam's maker, Matrixx Initiatives, of Scottsdale, Ariz., contends Zicam is safe. It blames the apparent side effects on the colds and infections that people were treating, not on the treatment.

It already agreed to settle about 340 Zicam claims for $12 million in 2006.

Richardson, 46, says he used Zicam just once. His mother, a retired nurse, offered him some for his stuffy nose. So he held the nasal gel to his nose, pumped and inhaled. He immediately felt a burning sensation but acknowledges that his sense of smell was already diminished by the cold. It was only when health returned - but not sense of smell -  he began to worry.

He went to the doctor and had an MRI, but nobody could figure out what was wrong. It was only when he did an Internet search for Zicam and saw all the lawsuits that he began to feel suspicious. One doctor has now tested his sense of smell and tentatively linked the problem to Zicam.

With months of medical care, Richardson says he has regained about 20 percent of his sense of smell.

He has complained to the FDA and engaged a personal injury lawyer but hasn't yet sued. "It finally feels good to feel like we're being heard," he said of the FDA's action.