When you have a chest infection and are coughing up a storm, the first thing you probably do is reach for the cough medicine. But hold on—it might actually do more harm than help.

Cough medicines are made of chemicals that have different uses. Some are used to block the cough reflex. Others loosen and thin or decrease the amount of mucus in your lungs, according to a video from the American Chemical Society. The question is: Do they follow through on their promise to make you feel better?

Even though you can find cough syrup in any cold medicine aisle, there’s no good evidence that they do much good. Some studies have found there isn’t enough data to claim they help, while others conclude they aren’t effective or it’s all just a placebo effect. 

Part of the problem might be that, annoying as it is, coughing actually is healthy when you’re sick. 'Coughing keeps material out of the lungs that doesn’t belong there,' Mark J. Rosen, MD, past president of the American College of Chest Physicians, tells Prevention. In fact, clearing phlegm out of your lungs by coughing helps rid your body of the infection more quickly, according to the U.K. National Health Service. Most infections will clear up on their own, but see a doctor if you show these 7 signs of pneumonia.

If you need to suppress a cough to get to sleep or stop freaking out your coworkers, stick with cough drops instead of liquid cough medicine, suggests the American Chemical Society. Those drops (or any hard candy, really) will kick up your saliva production to soothe your throat. Plain old water will also help, because fluids thin out mucus to cut down the coughing.