Americans spend billions of dollars on cough syrup per year. We think we’re paying for the privilege of feeling better—but according to the American Chemical Society's latest Reactions video, we might be swallowing a lie.
Scan the label of a typical cough medicine, and you’ll likely notice at least one (or more) of the following ingredients: a cough suppressant called dextromethorphan, or DXM; expectorants like guaifenesin, which thin and loosen mucus in the lungs; decongestants like ephedrine; and antihistamines like loratadine.
DXM will probably make you drowsy. But aside from getting a good night’s sleep, multiple systematic reviews (that’s scientist-speak for literature reviews that collect and analyze multiple studies or papers) have found little concrete evidence that these concoctions improve cold symptoms. In fact, clinical trials suggest that cough medicines are just as effective as—get this—a placebo.
If you’re looking to tame the tickle in your throat, you might be better off drinking plenty of fluids, taking a steamy shower, drinking tea with honey, and sucking on a cough drop or hard candy, as they soothe the throat by increasing saliva production. However, if you’re a staunch devotee of over-the-counter medicines, there aren’t any concrete findings stating that cough syrup doesn’t work. Take it if you notice an improvement—but make sure you don't consume too much of the medicine to amplify its effects, as large doses of DXM can cause dizziness, uncontrollable eye movement, convulsions, and in some extreme cases, even death.