What to Know About Expectorants

A Common Type of Cough Medicine

An expectorant is a type of cough medicine that thins and loosens mucus. These medications are typically used for managing the effects of chest congestion, especially when symptoms are caused by persistent mucus.

Woman blowing nose
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Guaifenesin, the most commonly used expectorant, is the active ingredient in Mucinex and Robitussin. In general, expectorants are available over-the-counter (OTC) in liquid, pill, and tablet forms.

Expectorants are part of the mucoactive class of drugs—those that clear mucus from the airways.


Expectorants are commonly used for management of the symptoms of acute (short-term) respiratory tract infections, like the common cold, pneumonia, or bronchitis.

These infections can cause a buildup of phlegm in your throat or lungs. It is often difficult to cough up this thick mucus, and you can develop a nagging cough and chest discomfort due to mucus accumulation.

Expectorants are designed to thin the respiratory secretions in your airways so that you can cough up excessive mucus more effectively. These medications do this by lubricating the airway passages.

Coughing up phlegm reduces discomfort from chest congestion. Coughing up debris and infectious material (like bacteria and viruses) may also lower the risk of infection.

It’s important to know that expectorants can make you more comfortable, but they don’t treat the underlying cause of chest congestion. You may need to use another treatment in addition to an expectorant—such as antibiotics or steroids—to treat the illness that is making you feel congested.

Off-Label Uses

Sometimes expectorants are used to manage congestion associated with chronic respiratory conditions like chronic obstructive pulmonary disease (COPD) or emphysema. If you have a chronic respiratory condition, you should not use an expectorant unless your healthcare provider recommends it.

Guaifenesin has also been considered to be possibly beneficial in the management of fibromyalgia, but it is not formally indicated as a treatment for the condition, nor is it yet clear why it may help.

Before Taking

You won’t typically need to have any tests before taking an expectorant. Your healthcare provider may recommend that you use one fairly early in the course of your illness, as soon as it becomes clear that mucus is the cause of your symptoms.

You should not take an expectorant if you have had an adverse reaction when using one in the past.

Precautions and Contraindications

You should talk to your healthcare provider before using an expectorant if you are pregnant or breastfeeding. If you have developed any type of allergic reaction or intolerance to expectorants in the past, you should not use these medications.

Use caution when driving or using machinery while taking an expectorant, as these medications can make you drowsy or dizzy.

Expectorants often come as combination medications, and you may have a contraindication to one of the other ingredients that are present in them. Be sure to carefully read labels.

Also, some combo-medications may contain a pain reliever, so be mindful of any individual pain relievers you may also consider taking, so as to not exceed the recommended dose.

Other Expectorants

There are a number of brand versions of guaifenesin, and it is also available in generic form.

Combination expectorants can help relieve the effects of a cold by using several different mechanisms of action at the same time.

Robitussin DM and Mucinex DM are composed of a combination of guaifenesin and dextromethorphan. Mucaphed is a combination of guaifenesin and phenylephrine (the active ingredient in Sudafed).


Given the variety of expectorants on the market—from liquids to tablets, regular and combination options, and so on—it’s important to follow your healthcare provider’s or pharmacist’s instructions and read the medication package carefully. You can expect to take long-acting versions fewer times per day than the regular formulations.

Do not crush pills, and be sure to measure liquid formulations using the measuring tools provided with your medication. It is often recommended that you drink plenty of fluids when taking an expectorant.

Store your medication according to the package instructions.

Side Effects

Expectorants do not commonly cause serious side effects. The most common side effects include dizziness, drowsiness, and rash.

Combination expectorants are more likely to cause side effects. Dextromethorphan, which is found in Robitussin DM and Mucinex DM, can cause drowsiness, dizziness, nervousness, restlessness, nausea, and vomiting.

Expectorant medications may be combined with dextromethorphan—a drug that may induce dependence and can also be a drug of abuse.

Warning and Interactions

Phenylephrine, a component of Mucaphed, can cause high blood pressure and bradycardia (a slowed heart rate). This medication may interact with antidepressants and heart medications.

A Word From Verywell

Keep in mind that home remedies for a cough and cold can help you feel better too. When you are sick, it is important to get enough sleep and follow a healthy diet.

Frequently Asked Questions

  • What is an expectorant used for?

    Expectorants are a type of cough medicine that thins mucus in the respiratory tract, making it easier to expel. An expectorant will not quiet a cough. It does the opposite: Expectorants make coughing more productive. 

  • What medications are expectorants?

    There are currently two expectorant ingredients available in the United States: guaifenesin and potassium iodide. Guaifenesin is the most commonly used expectorant in many cold, cough, and flu medications. Potassium iodide is widely used in breathing treatments for people with asthma, chronic bronchitis, or emphysema. 

  • What is the main ingredient in Mucinex?

    Guaifenesin is the main ingredient in Mucinex. An expectorant, guaifenesin helps to loosen up chest congestion, making it easier to cough up. 

  • Should I take an expectorant during the day or at night?

    Guaifenesin and other expectorants work best during the daytime. An expectorant will cause you to cough more to clear congestion from the respiratory tract. While you can take it at night, it will not help you sleep and may keep you awake.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kardos P. Management of cough in adults. Breathe. 2010;7:122-133. doi:10.1183/20734735.019610

  2. Parsons J. What does the color of phlegm mean? The Ohio State University Wexner Medical Center.

  3. National Library of Medicine. Guaifenesin.

  4. Ramos FL, Krahnke JS, Kim V. Clinical issues of mucus accumulation in COPD. Int J Chron Obstruct Pulmon Dis. 2014;9(1):139-150. doi:10.2147/COPD.S38938

  5. MedlinePlus. Guaifenesin.

  6. MedlinePlus. Dextromethorphan.

  7. Food and Drug Administration. Highlights of prescribing information—phenylephrine hydrochloride.

Additional Reading

By Deborah Leader, RN
 Deborah Leader RN, PHN, is a registered nurse and medical writer who focuses on COPD.