What Is a Mucolytic?

A drug designed to break up and loosen mucus

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Mucolytics are a class of drugs used to break up and thin mucus and make it easier to clear from the airways by coughing it up. Mucinex (guaifenesin) is a common example of a mucolytic.

Mucus is the gelatinous goo produced by mucous membranes of the lungs. It's common in people who have respiratory conditions.

Mucolytics are used to treat respiratory conditions such as the common cold, chronic obstructive pulmonary disease (COPD), cystic fibrosis, and other conditions marked by excess mucus and a productive (mucus-producing) cough.

This article looks at the many uses of mucolytic drugs as well as the different brands and formulations available over the counter and by prescription. It also walks you through how mucolytics are taken, as well as possible side effects and who shouldn't take them.

A pill capsule on a white background
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When You Might Need a Mucolytic

Mucolytics are used to treat conditions characterized by the acute (sudden and severe) or chronic (persistent or recurrent) overproduction of mucus in the airways, including:

  • Asthma: This is a chronic respiratory condition that causes the narrowing of the airways and overproduction of mucus in response to environmental triggers>
  • Bronchiectasis: This is the permanent widening of the airways caused by diseases like cystic fibrosis and tuberculosis.
  • Common cold: This is a common infection caused by any one of over 200 viruses, including rhinoviruses and adenoviruses.
  • COPD: This includes chronic bronchitis and emphysema.
  • Cystic fibrosis: This is an inherited genetic condition that causes the overproduction of mucus in the lungs and other organs.
  • Pneumonia: This is generally a bacterial infection that inflames the air sacs (called alveoli) in one or both lungs.
  • Tuberculosis: This is a potentially serious infection of the lungs caused by a bacteria called Mycobacterium tuberculosis.

Though mucus plays an important role in the lungs—trapping irritants so that they can be expelled through coughing—overproduction can lead to shortness of breath, persistent "wet" coughs, and other potentially debilitating breathing problems.

Overproduction of mucus is caused by the inflammation these conditions cause in the lungs. This natural defense against injury or disease ends up causing tissues to swell. This includes goblet cells, which normally make and secrete mucus, but do so in excess when swelling is present.

Types of Mucolytics

Mucolytics belong to a group of mucoactive agents. They work by reducing the viscosity (thickness and stickiness) of mucus in the airways. They do so by dissolving the chemical bonds within the secretions, causing them to thin so they can be coughed up more readily.

There are two types of mucolytics used in specific circumstances:

  • Classic mucolytics: These are the more common form found in both over-the-counter (OTC) and prescription medications. They contain active agents like carbocysteine, erdosteine, guaifenesin, and N-acetylcysteine.
  • Peptide mucolytics: These are used for more serious conditions like cystic fibrosis in which the mucus is thicker and often contains pus. These include ingredients like dornase alfa or thymosin beta-4.

Other Mucoactive Agents

Mucolytics is one of four types of mucoactive agent, each of which has different mechanisms of action and treat the overproduction of mucus in different ways.

The other types of mucoactive agents are:

  • Expectorants: These thin mucus by drawing water from the airways.
  • Mucokinetics: These increase the movement of the airways to help clear mucus.
  • Mucoregulators: These suppress the action of goblet cells and the production of mucus.


Mucolytics can be taken orally (by mouth) in tablet, capsule, or syrup form. Or, it can be inhaled either with an aerosol inhaler or in a mist form through a machine called a nebulizer.

The dosage varies by the drug, formulation, and condition being treated.

OTC formulations are generally taken two to three times daily at the prescribed dose. Taking more than the recommended dose won't make the drug more effective but may only serve to increase the risk (or severity) of side effects.

Some of the more common OTC mucolytics include:

  • Mucinex (guaifenesin): Available as a tablet and syrup
  • Mucolyte (bromhexine): Available as tablets, dissolvable tablets, and syrups

Prescription mucolytics are prescribed by a healthcare provider. The drugs may be used to treat acute episodes or taken on a daily basis to manage severe respiratory diseases like cystic fibrosis.

Some of the more common prescription mucolytics include:

  • Availnex (carbocisteine): Available as a tablet, chewable tablet, and inhaler primarily for the treatment of emphysema and cystic fibrosis
  • Ectrin (erdosteine): Available as a capsule, tablet, granules, and powder primarily for the treatment of chronic bronchitis
  • Mucomyst (N-acetylcysteine): Delivered by a nebulizer and used for conditions like COPD, cystic fibrosis, and pneumonia
  • Pulmozyme (dornase alfa): Delivered by nebulizer for the treatment of cystic fibrosis
  • TB-500 (thymosin beta-4): Delivered by nebulizer for the treatment of cystic fibrosis

Possible Side Effects

The side effects of mucolytics also vary by drug type and formulation. OTC mucolytics like Mucinex or Mucolyte may, on occasion, cause mild side effects such as:

  • Dizziness
  • Headache
  • Drowsiness
  • Stomach upset
  • Nausea or vomiting

Many of the same can occur with prescription mucolytics, along with diarrhea, rash, and dark stools (due to gastric bleeding). Nebulized or aerosolized mucolytics can also cause sore throat, runny nose, and white patches in the mouth (due to oral thrush).

Precautions and Contraindications

Mucolytics are generally considered safe when used as prescribed, but they should not be used in children under 6. You should also consult your healthcare provider before taking mucolytics if you are pregnant or breastfeeding.

Do not take mucolytics if you have a stomach ulcer, as they can make it worse.


Mucolytics are a class of drugs that break up mucus in the airways so that it can be coughed up more easily. Some are available over the counter, while others require a prescription from a healthcare provider.

Mucolytics can treat a wide range of respiratory conditions involving excess mucus in the airways, including asthma, bronchiectasis, the common cold, COPD, cystic fibrosis, pneumonia, and tuberculosis.

A Word From Verywell

OTC mucolytics like Mucinex are effective, but they are not intended for long-term use.

If you continue to have a persistent or worsening cough with mucus after seven days, call your healthcare provider. Other, more effective treatments may be needed.

3 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.
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  2. Global Initiative for Chronic Obstructive Lung Disease. Pocket guide to COPD diagnosis, management, and prevention: a guide for health care professionals (2017 report). 2017

  3. Yoon H, Lee DH. Mucolytics as adjuvant agent to improve helicobacter pylori eradication rate: still long and winding road to positive resultsGut Liver. 2015;9(3):257–258. doi:10.5009/gnl15117

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