Acetylcysteine: What You Need to Know

Acetylcysteine is prescribed to help treat respiratory processes, especially when they involve excessive mucous secretion, or when mucus is very thick. We'll explain everything you need to know about this drug in the following article.
Acetylcysteine: What You Need to Know

Last update: 08 February, 2023

Acetylcysteine is a medicine used to thin mucus. Therefore, it helps to expel bronchial secretions when they’re excessive. Normally, its use is recommended to help overcome respiratory processes accompanied by chest congestion and respiratory distress.

How does it work? The mechanism of action

Acetylcysteine belongs to a group of medicines called mucolytics. A mucolytic facilitates the fluidization of mucus to favor its elimination by physical means, that is, by coughing. Therefore, it reduces the amount of secretions retained in the respiratory processes and also reduces the frequency and intensity of a person’s cough.

There are different types of mucolytics. Acetylcysteine is an amino acid and its activity is due to sulfur groups that it contains in its chemical composition. These groups attack glycoproteins that are part of the mucus, altering its structure and causing it to thin.

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What is acetylcysteine prescribed for?

Acetylcysteine is prescribed to help treat respiratory processes, especially when they have excessive mucous secretion, or when it’s very thick. These symptoms usually appear in diseases such as the following:

  • Acute or chronic bronchitis.
  • Chronic obstructive pulmonary disease, also known as COPD.
  • Pulmonary emphysema
  • Other illnesses related to the respiratory system, mainly.

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How should I take acetylcysteine?

In general, the recommended average dosage is as follows:

  • For adults, 600 mg of acetylcysteine per day. It can be taken in a single 600 mg dose or in three 200 mg daily doses.
  • In children older than 7 years, the same dose is recommended as for adults. In other words, a dose of 600 mg per day.
  • For children between 2 and 7 years old, the recommended average dose is 300 mg of acetylcysteine per day. In this case, it’s best to divide the dose into three intakes of 100 mg each and space them out every 8 hours.
  • Its use is contraindicated in children under two years of age.

This medication can be obtained at the pharmacy in different presentations and from different laboratories. On the one hand, as we’ve said, there are different doses: 100 mg, 200 mg, and 600 mg. On the other hand, you can find it in sachets or effervescent tablets.

In any case, it’s administered orally, dissolving the contents of the sachet or effervescent tablet in a glass with a little water. By doing so, you’ll obtain a quite pleasant-tasting solution that you can drink directly from the glass.

Keep in mind that it’s a drug subject to medical prescription. So, if you have any questions, you should ask your doctor or trusted pharmacist.


What should I keep in mind before taking acetylcysteine?


Acetylcysteine is contraindicated in patients who have hypersensitivity or allergy to this drug or to any of the excipients it contains. If you’re allergic to certain compounds, don’t forget to check the list of excipients. Although a presentation from one laboratory may contain lactose, for example, that doesn’t mean that all presentations have it in their composition.

In addition, its use is contraindicated in people suffering from asthma, severe respiratory failure, or gastroduodenal ulcer, and also in children under two years of age.

Other warnings or precautions

  • Interactions with other drugs: Although no interactions with other medications or treatments have been identified, taking this drug along with antitussives or with other drugs that reduce bronchial secretions isn’t recommended.
  • Pregnancy and lactation: The results of the studies don’t indicate danger or harm to the fetus. Still, acetylcysteine administration is recommended under medical supervision during pregnancy. Likewise, the same is recommended for breastfeeding women, as it’s unknown whether acetylcysteine can pass into breast milk.
  • Adverse reactions: The most frequent side effects are gastrointestinal in nature. Some of them may be nausea, vomiting, or diarrhea, but they’re usually mild, transitory, and in low proportion. Less frequently, allergic reactions may occur accompanied by reddened skin and/or difficulty breathing. In this case, you should stop treatment and see a doctor.

Other clinical uses of acetylcysteine

As we’ve commented, the main use of acetylcysteine is as a mucolytic to help the treatment of respiratory conditions. But there are studies that claim that it also has other benefits, such as antioxidant or anti-inflammatory effects. At the same time, acetylcysteine is used as an antidote in paracetamol poisoning.

  • Agencia Española de Medicamentos y Productos Sanitarios (AEMPS). Ficha técnica Acetilcisteína. 2013;4–7.
  • Comité de Redacción Científica de SIIC. Actualizan el Uso Terapéutico de la N-Acetilcisteína y los Mecanismos de Acción Involucrados. Ser Indicaciones Ter la N-Acetilcisteína. 2011;65(9):549–57.
  • Esteva E. Antitusivos, expectorantes y mucolíticos. OFFARM. 2008;27(11).

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