Are you ready to learn about Acetylcysteine? If so, you’re in the right place because that is what this guide is all about.

So if you’re ready, let’s go ahead and get started.

Medical Disclaimer: This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Please consult with your physician with any questions that you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you read in this article.

What is Acetylcysteine?

Acetylcysteine is a medication that primarily is given to help break up mucus and secretions in the airways of the lungs.

But before we go a bit deeper, let’s first talk about the name. You may have seen 3 different versions of this medication:

  • Acetylcysteine
  • N-Acetylcysteine
  • Mucomyst

Acetylcysteine is the generic name. Or you maybe you’ve heard or seen it written as N-Acetylcysteine (NAC).

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And last but not least, my favorite is the brand name, which is — Mucomyst.

The name Mucomyst helps make learning the drug easy because it literally has Muc in the name. This can help you remember that it’s administered to help clear mucus.

Acetylcysteine is a mucolytic agent and, to be more specific, it’s an amino acid that can break down the thick mucus that interferes with breathing.

What is a Mucolytic Agent?

Mucolytic agents are a class of drugs that are used to help break up mucus. If you aren’t familiar with this term, mucolytic literally means, “mucus-dissolving.”

Visit this link for our full study guide on Mucus-Controlling Drugs.

When is Acetylcysteine Indicated?

As I said, since it’s given to help break up retained secretions, it would be indicated in patients with conditions such as:

  • Cystic Fibrosis
  • COPD

With that said, there are several studies out there that argue if it’s actually effective in treating Cystic Fibrosis or not. Dornase alfa, a different mucolytic agent, been shown to be more effective in treating Cystic Fibrosis patients.

Acetylcysteine has also been used in postoperative patients as a diagnostic aid. And it’s sometimes used in patients with a tracheotomy as well.

Acetylcysteine can also be used as a treatment for an acetaminophen overdose, but more on that later.

For now, we’re still focusing on the mucus side of things.

Dosage for Acetylcysteine

This medication is available in different dosage forms for different indications:

  • Solution for inhalation – inhaled for mucolytic therapy via a small volume nebulizer. For adults, typically you will see a 20% solution in 3-5 mL doses that are given 3-4 times per day.
  • IV injection – treatment for an acetaminophen overdose
  • Oral solution
  • Tablets

Example TMC Practice Question:

The physician has ordered acetylcysteine for a 66-year-old female patient with COPD who has a large amount of thick secretions. Upon assessment, you note that the patient has a weak, inadequate cough. Which of the following would you recommend?

A. Perform a bronchoalveolar lavage
B. Nasotracheal suctioning after the treatment
C. Postpone the therapy until the patient can cough effectively
D. Administer dornase alpha instead of acetylcysteine

There are a few things about this question that stand out, so let’s break it down. First, you needed to know that acetylcysteine is another name for Mucomyst, which is a drug that is typically given for retained secretions.

Also, you needed to recognize that the question tells us the patient has an inadequate cough. This means that they will have trouble clearing secretions on their own, which tells us that some type of intervention must be performed.

Of the answer choices that are listed, the best way to help remove the secretions would be to NT suction the patient after the treatment is given.

Dornase alfa (Pulmozyme) is a medication that is used to treat patients with cystic fibrosis, and none of the other answer choices really make sense in this situation. So by breaking it down, we now know that the correct answer has to be B.

The correct answer is: B. Nasotracheal suctioning after the treatment

This practice question was actually taken from our TMC Test Bank, which is a massive bank of premium practice questions that cover every topic that students must know in order to pass the TMC Exam.

As you can see, each question comes with a detailed rationale that explains exactly why the answer is correct. This is critical when it comes to actually learning the information.

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Side Effects of Acetylcysteine:

First and foremost, I feel like I need to get this off my chest. Let’s talk about the odor.

If you’re a Respiratory Therapist like me, or even if you’re a nurse, physician — anyone who has worked with a patient receiving Mucomyst via SVN — I think you would agree that the medication has a distinct, recognizable smell.

Mucomyst Has a Bad Smell.

Okay, I’ll be honest. It smells really bad. I mean, since we’re being honest here, it smells like rotten eggs to me. 

This is just my opinion, of course. I don’t know, maybe you like the smell. But there’s no denying that it’s easily recognizable.

So, while technically no a side effect, this is something that you should be aware of.

More Side Effects of Acetylcysteine:

  • Bronchospasm
  • Wheezing
  • Shortness of breath

You’re probably thinking, “I thought this medication was given to help make breathing easier for the patient?”

Well, yeah. It is supposed to make breathing easier. It does so by breaking up the secretions.

But in doing so, it actually causes bronchoconstriction. So to counteract this, a short-acting bronchodilator should be administered before administering the Mucomyst.

It may also be indicated to accompany aerosol therapy with bronchial hygiene or airway clearance therapy as well, depending on the patient’s condition.

Other Side Effects of Acetylcysteine include:

  • Rash
  • Itchiness
  • Hypotension
  • Drowsiness
  • Nausea
  • Vomiting
  • Fever

Contraindications for Acetylcysteine:

Since we’ve already discussed when Acetylcysteine is indicated, now you need to know when you wouldn’t want to administer the drug.

As we said before, since bronchospasm is a side effect of the drug, you shouldn’t give Acetylcysteine to patients with asthma.

Especially during an acute episode.

Also, you need to be aware of the patient’s ability or inability to cough. When Acetylcysteine is given, because it helps to loosen up mucus in the airways, this means that more secretions will need to be expectorated by the patient.

So this could be problematic if the patient cannot generate a cough that is strong enough to remove the secretions.

In such a case, frequent suctioning may be indicated.

Some people think it’s easy being a Respiratory Therapist but it’s SNOT.

Acetylcysteine to Treat an Acetaminophen Overdose

As I briefly mentioned earlier, Acetylcysteine is given to treat an acetaminophen overdose as well.

To put it simply, the drug helps replenish depleted reserves in the liver that can enhance the non-toxic metabolism of acetaminophen. It’s most effective if administered within 8–10 hours after the overdose.

When given for an acetaminophen overdose, it can be given orally or IV — both, of which, are effective for this indication.

Pharmacokinetics of Acetylcysteine

If you’re wanting to get into the Pharmacokinetics of Acetylcysteine, that’s beyond the scope of this article.
Just know that the drug is metabolized by the liver. It has a half-life of 5.6 hours in adults and 11 hours in neonates. And urine excretion is 22-30%.

What is the Difference Between Acetylcysteine and Mucomyst?

There is no difference between the two — they are the same medication. As I stated earlier, Acetylcysteine is the general name of the drug, whereas Mucomyst is the brand name.

The names can be used interchangeably, along with N-Acetylcysteine (NAC).

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What Other Drugs Interact with Acetylcysteine?

Acetylcysteine has no known severe or serious interactions with other drugs. With that said, there are some moderate and mild interactions with other medications.

Just to be safe, always tell your doctor or pharmacist of all the medications that you use.

This article is for informational purposes only and is not to be mistaken for medical advice. As always, check with your doctor or health care professional if you are seeking medical advice.

Final Thoughts

So there you have it. Now you know pretty much everything that there is to know about Acetylcysteine.

Hopefully this information was helpful for you. If you haven’t done so already, definitely be sure to subscribe to our YouTube channel because we really break topics such as this one down in our videos.

Also, don’t forget to download your free copy of our Mucus Color Guide as well. Thank you so much for reading all the way to the end, and as always, breathe easy my friend.


The following are the sources that were used while doing research for this article:

  • Faarc, Gardenhire Douglas EdD Rrt-Nps. Rau’s Respiratory Care Pharmacology. 10th ed., Mosby, 2019. [Link]
  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020. [Link]
  • “Medical and Dietary Uses of N-Acetylcysteine.” PubMed Central (PMC), 1 May 2019,
  • “Overview on the Effects of N-Acetylcysteine in Neurodegenerative Diseases.” PubMed Central (PMC), 1 Dec. 2018,

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