While it's often best to walk away, that can be difficult in today's team-based workplace, where many people work closely in groups.

Trying to stay neutral by just listening and nodding can also backfire, says Dana Brownlee, founder of Professionalism Matters, a corporate-training firm in Atlanta. "Before you know it, there's another version of the story circulating, saying you were the one saying something negative about the VP. And they're talking about you over by the Coke machine."

And it can be tough to object without seeming self-righteous. "If you approach someone about their complaining, they may take it in a completely wrong way, and then you've alienated them," says Jon Gordon, an author, consultant and founder of a Ponte Vedra Beach, Fla., training firm. It's better to try to bond with co-workers, while setting an example by not griping yourself, he says.

When Kris Whitehead joined a new employer several years ago, his colleagues' frequent work complaints "had a direct impact on my ability to sell," says the Nashua, N.H., salesman. With the economy in a slump, "I had the same secret fears" of failure being voiced by co-workers, he says. Staying upbeat "was an extremely arduous task."

But when he suggested to colleagues that they focus instead on solutions,"nobody wanted to listen," he says. Plus, "people started talking about me at the water cooler."

Mr. Whitehead started reading books on personal development and worked on bonding with colleagues. As he posted gains in sales, co-workers warmed up and his boss recently asked him to help train new hires. "People seem to listen better when you produce," Mr. Whitehead says.

But research shows productivity can be damaged by toiling alongside a chronic complainer. Exposure to nonstop negativity can disrupt learning, memory, attention and judgment, says Robert Sapolsky, a prominent author and professor of neurology and neurological sciences at Stanford University. The brain, he says, can only handle so many stimuli at once before it begins losing ability to concentrate or remember—especially if that steady stream of negativity sparks distressing emotions.

Complainers who are highly emotional, or who target a problem that also makes the listener feel wronged, can especially darken a co-worker's mood, Dr. Sapolsky says.

Whining has become so common that many people don't even realize they're doing it. Benjamin Ballard, an account manager for PaceButler, an Oklahoma City company that recycles cellphones, says he used to moan at work about his migraines. But "I'd make jokes about it and thought that somehow made it positive," says Mr. Ballard.

PaceButler CEO Tom Pace made such grousing a front-and-center issue last December by offering cash rewards to any of his 70 employees who could refrain from complaints or gossip for at least seven days. Participants in the challenge monitor themselves and each other, wearing rubber wrist bracelets that they move to the other arm when they slip. Workers who say they have gone a week without such toxic talk are eligible to enter a monthly $500 drawing.

For his part, Mr. Ballard stopped griping and took action to stop the headaches by eating better, he says. "I don't get headaches anymore." Spending less time talking about them, he figures, has helped.

His colleague Debbie Gutierrez, an agent coordinator, says the program has made everyone stop and think before they talk. "You can see growth in people," she says. And throughout the office, Mr. Pace says, "there are more high-fives, more laughter and more production."

Still, in most companies, it's getting harder to avoid the grumblers. Some 18% of U.S. employees are "actively disengaged," negative and likely to complain about their employers, according to an annual Gallup poll of 31,265 employees. That negativity can spread "kind of like a cancer," says Jim Harter, Gallup's chief scientist for workplace management and well-being.

Work groups with a high rate of negativity tend to have lower productivity and higher rates of absenteeism and quality defects, the Gallup research shows. If an opportunity arises to invest extra effort to help the company, these workers are likely to pass it up, Dr. Harter says.

But there are ways to cope with complainers. When people beef about the boss or someone else, author and speaker Will Bowen suggests deflecting the gripes by saying, "It sounds like you and he have something to talk about." Other people bellyache just to get attention. He suggests giving the complainer a different kind of attention by asking, ' "What's going well for you?" They'll look at you like you're crazy at first,' but persist and "the person will either switch topics or stop talking to you. Either way, you don't have to listen to them any more," says Mr. Bowen, Kansas City, Mo., founder of a nonprofit group, A Complaint Free World.

Of course, "there has to be some healthy conflict," says Mr. Gordon, the author and consultant. When work teams get together, the ratio of positive interactions, such as support and encouragement, to negative interactions, such as disapproval and criticism, should be about 3-to-1 or higher in order to ensure top performance, based on research by Barbara Fredrickson, a psychology professor at the University of North Carolina, Chapel Hill, and others.

And some chronic complainers expose real problems. Joan Curto griped almost constantly years ago about the heavy travel required by her job as a national accounts manager for a drug company, says her former boss, Trevor Blake. "She complained about everything: The company car wasn't big enough, the bonuses weren't good enough," says Mr. Blake, a Seattle-based entrepreneur and author. "I pushed back, asking, 'What are you going to do about it? Come to me with a solution.' "

At first, Ms. Curto says, she was irritated. She was traveling four to five days a week trying to cover a huge 600-hospital sales territory and was seldom home with her family. But she soon figured out what Mr. Blake calls "a brilliant plan" to limit face-to-face visits to customers with the highest sales potential, and to hire a pharmacist to contact the rest.

The result: Sales went up, and Ms. Curto, now a sales manager for a different, Chicago-based company, got to stay home more often with her family.