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What Are the Active Ingredients in Cough Syrup?

People often say that “It’s Never Just a Cough” because there is a lot of truth to it. If you find yourself suffering from a nasty cough because of a cold or flu, it’s extremely important to understand why you’re coughing and, more importantly, which cough medicine is the best course of treatment. Common cough syrup ingredients include dextromethorphan and guaifenesin, but they treat different symptoms. Learn what dextromethorphan and guaifenesin are used for and how they can relieve your dry and wet cough.

Women coughing

Dry Vs. Wet Cough

Dry cough often occurs because of an upper respiratory tract infection in the nose and/or throat caused by a cold or flu. However a dry, hacking cough can also be an early sign of a lower respiratory infection in the trachea, bronchi and/or lungs. In either situation, this type of cough can become worse at night or if you’re exposed to extremely dry air or irritants such as dust, pollen or smoke.

A wet cough usually occurs due to a build-up of fluid secretions and mucus in the lower respiratory tract due to an infection. Your body’s natural reaction to remove these fluids from your windpipe and lungs is to cough.

What Is Dextromethorphan and Guaifenesin?

When it comes to relieving your cough, dextromethorphan and guaifenesin are two key ingredients in cough medicine that often work together to ease your cough symptoms. However, while dextromethorphan and guaifenesin typically work together in one medication, each ingredient targets a specific aspect of your cough. So, it can be helpful to know what each ingredient does when choosing your cough relief syrup.

What Is Dextromethorphan Used For?

Dextromethorphan Hbr (Hydrobromide) is a cough suppressant that is particularly effective as a dry cough medicine. Dextromethorphan, or DXM for short, is an ingredient that works in the brain and central nervous system to target signals that trigger the cough reflex and ultimately help reduce the urge to cough. DXM is the main ingredient in over-the-counter (OTC) cough products such as Robitussin 12 Hour, a powerful dry-cough-relief medicine.

What Is Guaifenesin Used For?

Guaifenesin is an expectorant, an ingredient that helps thin and loosen the excess phlegm in your air passageways. Effective in addressing chest congestion, guaifenesin helps make it easier to cough up secretions and breathe. †† The more secretions you can cough up and purge from your respiratory tract, the less congested you will be. Guaifenesin would be your go-to ingredient when battling a wet cough.2

Robitussin Cough and Chest Congestion products contain both dextromethorphan and guaifenesin to treat both symptoms. Dextromethorphan suppresses your cough while guaifenesin works as an expectorant to clear your chest congestion and help drain your airways. Explore all of our products and see which is best for you.  

Source Citations:


  1. Types of Coughs: Causes, Symptoms, and When It’s Serious. Healthline. (Source from the original article published on
  2. Guaifenesin. MedlinePlus Drug Information. Accessed 11/8/22.
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  • This product contains the active ingredients Dextromethorphan.
  • **This product contains the active ingredients Dextromethorphan and Guaifenesin.
  • *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
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