What to Know About Expectorants

A common kind of cough medicine

Woman blowing nose
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An expectorant is a type of cough medicine that thins and loosens mucus. These medications are typically used for managing the symptoms of chest congestion. Guaifenesin, the most commonly used expectorant, is the active ingredient in Mucinex and Robitussin.

In general, expectorants are available over-the-counter (OTC), without a prescription.


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 build-up of phlegm —a thick mucus—in your throat or lungs. It is often difficult to cough up phlegm, and you can develop a nagging cough and chest discomfort due to the 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 work by lubricating the airway passages (making them more watery).

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.

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.

Off-Label Uses

Sometimes expectorants are used for managing 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 doctor 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 fibromyalgia and it isn't yet clear whether it is useful in treating the condition.

Before Taking

It is often recommended to drink plenty of fluids when taking an expectorant.

You should talk to your doctor 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.

Precautions and Contraindications

You should use caution when driving or using machinery because 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 your combination medication.

Other Expectorants

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

Potassium iodide, a medication used to treat certain thyroid disorders, is also an expectorant, but it is not used as commonly as guaifenesin.

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).

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


Expectorants are available in pill, tablet, and liquid form. They are also available in long-acting forms. The long-acting versions are taken fewer times per day than the regular formulations.

Because different combination expectorants are dosed differently, you need to follow your doctor or pharmacist's instructions and read the package carefully. Do not crush pills, and be sure to measure liquid formulations using the measuring tools provided with your medication.

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, sedation, constipation, diarrhea, and confusion.

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 colds can help you feel better too. When you are sick, it is important to get enough sleep and follow a healthy diet.

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