Feeling a little under the weather? Turns out your co-worker could be to blame, even if they’re perfectly healthy. According to a joint study by the University of Calgary’s School of Business and The London School of Economics toxic co-workers can have a negative reaction on your health. These are people who are rude, make unfair demands of you and make the workplace an uncomfortable place to be. The study found that people who have to deal with toxic coworkers on a daily basis reported symptoms that included headaches, stomach problems and sleepless nights. In one case, a woman named Cari said the endless demands from her supervisor caused her hair to fall out in clumps. Experts say there are things you can do to improve your situation. First try putting yourself in their shoes, sometimes they have personal issues going on and are taking it out on the people around them. Second, call them out. More often than out people who are being rude don’t realize it. If it continues report the behavior to your supervisor. And if all else fails call in sick.