OTC Cough Medicine: What Works, What Doesn't, and What to Watch For

When you're stuck with a nagging cough, OTC cough medicine, over-the-counter drugs sold without a prescription to relieve cough symptoms. Also known as cough syrup, it's one of the most bought drug categories in the U.S.—but not all of it actually helps. You might grab a bottle because it’s on sale, or because your neighbor swears by it, but here’s the truth: many of these products contain ingredients that don’t work for most coughs, and some can even make things worse.

The two main types you’ll find are cough suppressants, drugs that quiet the cough reflex in your brain. Also known as antitussives, they’re meant for dry, hacking coughs. The most common one is dextromethorphan, a non-narcotic ingredient found in dozens of brands like Robitussin and Delsym. Also known as DM, it’s the go-to for temporary relief, but studies show it only works slightly better than sugar pills for most adults. Then there’s expectorants, drugs that thin mucus so you can cough it out easier. Also known as mucolytics, the only one proven to work in real-world use is guaifenesin, found in Mucinex and generic versions. It doesn’t stop the cough, but it helps if your chest feels heavy and you’re struggling to clear phlegm.

Here’s what most people don’t realize: if your cough comes from a cold or the flu, your body is doing exactly what it’s supposed to do—clearing out germs. Suppressing it might feel good in the moment, but it doesn’t speed up recovery. And if you’re over 65, or taking other meds, some OTC cough syrups can cause dizziness, confusion, or even dangerous heart rhythms. Even the harmless-looking ones can interact with antidepressants, blood pressure pills, or sleep aids. That’s why checking labels isn’t optional—it’s your first line of defense.

And don’t be fooled by multi-symptom formulas. If you only have a cough, you don’t need antihistamines, decongestants, or pain relievers mixed in. Those extra ingredients increase side effects without helping your cough. The best OTC cough medicine is the one with the fewest ingredients that match your symptoms. Simple. Focused. No fluff.

Below, you’ll find real breakdowns of what’s in those bottles, how to spot the ones that actually work, and the hidden risks you might not know about. No marketing. No hype. Just what the science says—and what your pharmacist won’t always tell you.