It can feel good to help someone out at work. Often, it’s a win-win proposition—your colleague gets your assistance with a problem or project, and you get the reward of thanks, which makes you feel appreciated. Or vice versa—you get a helping hand and your gratitude lifts up your work friend.

But it often doesn’t work out so well. Sometimes being helpful at work can backfire—both for the person lending a hand and for the recipient. The bad vibes can linger, too.

The difference between a good outcome and a less-than-optimal one rests on a seemingly small but actually quite significant distinction—what prompted the assistance in the first place.

Looking at Help from Both Sides

Workplace research on helping behavior and the gratitude it engenders had generally focused on the well-being of people who provide assistance to their coworkers. And yes, it generally feels good to help—at first. But what about the people being helped—how do they feel? And how do their responses, positive or negative, affect the helper’s feelings and motivation?

To explore these dynamics, researchers at Michigan State University recruited 54 men and women, ages 21 to 60. They were employed full-time in a variety of industries including manufacturing, government, health-care and education. Over the course of two workweeks, participants filled out daily surveys that assessed, on a five-point scale, how helpful to coworkers they had been at work that day, the degree of gratitude they received from coworkers they helped and whether they felt their help had benefited others. They also assessed the effect it all had on their engagement with their own work—whether helping made them feel more positive and engaged, or, on the other hand, depleted of energy.

A key part of the survey focused on the kind of help participants provided. Proactive help is help that’s unsolicited or offered without being requested. Reactive help is help that’s provided in response to someone asking for it.

In a second study with the same participants, the researchers asked additional questions about whether the helpers had a clear understanding of the problems and issues they had helped someone with. They also delved into the experience of those who had been helped—how much they had needed the help, how effective it had been and whether they perceived the assistance as being a threat to their self-esteem, competence and/or autonomy. And perhaps the most surprising result was, when help was offered proactively, it had negative effects on both givers and recipients.

When help wasn’t asked for, recipients were more likely to regard it as unneeded and not particularly effective and to experience it as a threat to their self-esteem, competence and autonomy at work. And that lead to a kind of domino effect that was bad for both parties—help recipients who hadn’t asked for help tended to delay thanking the person who had assisted. And then the helper tended to feel less motivated at work the next day.

In contrast, reactive helping—lending a hand when someone asked for it—benefited both the giver and the recipient. The person being helped was much more likely to feel gratitude and to express it promptly. The person doing the helping got a psychological boost from that expression of gratitude, which in turn improved engagement and a positive attitude toward work.

Minding Your Own Business

The old cliché holds true: It’s generally better to keep your nose in your own business. Resist offering unsolicited help to a coworker, focus on your own job and wait to be asked for help if/when it’s needed. When you do that, your efforts are more likely to be welcomed and rewarded, and your sense of well-being will receive a healthy boost. And if you’re on the receiving end of a colleague’s help, remember to say thank you promptly—providing assistance can be taxing and can slow your coworker’s progress on his/her own tasks.

What if you simply can’t resist offering unsolicited help? The researchers don’t encourage it, of course, but they do suggest that it may be possible to mitigate the potential negatives. First, show respect and empathy for the coworker and the challenge—and then help your coworker discover his/her own route to solutions rather than offering the solution yourself. It might be faster and feel good to just fix it yourself, but it won’t end up making either of you feel good…or motivated.