ACC

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Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of ACC

What is ACC? Identity and Classification Overview

Property Description
Active ingredient Acetylcysteine (N-Acetyl-L-cysteine, NAC)
Form Effervescent tablets, oral solution, nebulization solution, injection
Pharmacological class Mucolytic, Expectorant, Antidote
Common use Easing clearance of thick respiratory mucus
Origin Synthetic L-cysteine derivative

Defining the Class and Identity of Acetylcysteine

The medicine known commonly as ACC contains the active ingredient Acetylcysteine, which is scientifically abbreviated as NAC (N-Acetyl-L-cysteine). It is primarily classified within the pharmacological class as a mucolytic and expectorant agent. Acetylcysteine is a synthetic compound, specifically a thiol compound derived from the amino acid L-cysteine. This chemical nature, supported by pharmacological studies, is key to its effect on secretions.

Acetylcysteine's core identity is marked by its critical dual role: it is widely used for respiratory support and also serves an essential, distinct purpose as an antidote. The drug is listed on the WHO Model List of Essential Medicines for its critical role in treating acute poisoning, specifically paracetamol overdose. The oral and effervescent forms of Acetylcysteine are typically available as over-the-counter (OTC) products, positioning them for patient self-management of common respiratory symptoms.

Forms, Composition, and General Purpose

Acetylcysteine is available in several distinct dosage forms, facilitating oral, inhalational, and intravenous administration routes. The common forms include effervescent tablets, oral solution, and powder for oral solution for oral intake, alongside solution for nebulization and sterile injection solution for clinical settings. The product is generally a single-active-ingredient product, containing only Acetylcysteine alongside necessary pharmaceutical excipients.

The fundamental purpose of Acetylcysteine is to reduce the thickness and tenacity of excessive viscous mucus secretion, aiding in expectoration and breathing. It achieves this physiological action by modifying the physical structure of the secretions, making it clinically recognized for treating conditions involving thick mucus accumulation. Furthermore, the injectable form is administered clinically to counteract acute toxic episodes by rapidly restoring depleted hepatic stores of glutathione, which is crucial for liver detoxification, providing a unique antidotal benefit beyond its respiratory function.

Regulatory References

  1. MedlinePlus Acetylcysteine Drug Information

What side effects are possible with ACC?

Possible Side Effects and Safety Information

The official safety profile of Acetylcysteine (ACC/NAC) documents adverse reactions and specific usage constraints as classified by government regulatory authorities.

Adverse events are categorized by frequency and the physiological system affected. Most commonly reported effects involve Gastrointestinal disorders, such as Nausea and Vomiting, which are classified as Common.

Uncommon side effects, occurring in less than 1 in 100 people, may include Hypersensitivity reactions, Headache, Tachycardia, and effects on the skin like Urticaria or Rash. Rare reactions, affecting less than 1 in 1,000 people, include Bronchospasm and Dyspnoea (shortness of breath).

Serious adverse reactions, though very rare, include systemic events such as Anaphylactic shock and severe skin conditions like Stevens-Johnson syndrome and Toxic epidermal necrolysis.

Safety Domain Regulatory Statement
Population Specific Contraindicated in children under 2 years for oral mucolytic use. Caution is advised for patients with a history of peptic ulcers or asthma.
Exposure Pattern Acute flushing and erythema related to intravenous use typically occur 30 to 60 minutes after initiating infusion.
Concomitant Use Restriction Use with Nitroglycerin may cause significant Hypotension. Use with antitussive drugs may lead to build-up of bronchial secretions due to reduced cough reflex.

These official classifications and constraints provide the regulatory basis for understanding the medicine's risk profile.

Overdose and Emergency Response

Overdose and When to Seek Help

Official regulatory documents mandate that immediate medical attention be sought and emergency services or a poison control center be contacted in all cases of suspected overdose. This urgent action is required due to the documented potential for severe, life-threatening outcomes listed in the prescribing information.

Overdose manifestations officially listed by government authorities typically include nausea, vomiting, diarrhea, headache, and flushing. More significant exposure can lead to documented clinical signs such as confusion, somnolence, hypotension (low blood pressure), and bradycardia (slow heart rate).

Severe outcomes documented by regulators include hepatic failure, acute renal impairment, and severe metabolic acidosis. The risk of serious anaphylactoid-like reactions, often involving sudden hypotension and bronchospasm, is noted in the context of rapid intravenous administration. Furthermore, regulators note that patients with pre-existing hepatic or renal impairment may face a higher risk of adverse outcomes following overdose.

For the overdose of Acetylcysteine itself, no specific pharmacological antidote is known; therefore, the treatment is officially described as symptomatic and supportive. This standard of care requires hospital monitoring, specific laboratory assessments, and continuous clinical observation.

Therapeutic Uses of ACC

What ACC Treats: Main Uses and Benefits

The therapeutic application of Acetylcysteine (ACC/NAC) spans two distinct domains and is considered relevant across therapeutic contexts.

This medication is commonly used to help manage the symptomatic burden in chronic respiratory diseases, such as Chronic Bronchitis, COPD, and Cystic Fibrosis, which are conditions characterized by abnormal, viscid mucous secretions. It plays a role in managing symptom clusters that create noticeable physiological strain by addressing the difficulty in clearing phlegm, which supports the patient with expectoration. The medicine is also applied as an essential antidote in the treatment of acute Acetaminophen (Paracetamol) overdose.

A key benefit of this drug is to address the difficulty in clearing airways caused by tenacious secretions, supporting a manageable symptomatic experience.

In acute clinical scenarios, this application is relevant in clinical contexts that involve acute and unstable symptom patterns stemming from potentially hepatotoxic exposure. The therapeutic benefit in this context contributes to easing the potential impact of acute toxicity and may assist in maintaining functional stability of the liver during a toxic episode.


Quick Fact: Relief for Thick Mucus Symptoms This medication provides supportive relief when excessive, thick secretions interfere with daily comfort, assisting with airway clearance in chronic conditions.

Regulatory References

  1. NIH StatPearls overview on N-Acetylcysteine

Eligibility and Restrictions for Use

Who Can and Cannot Use ACC?

The eligibility for using Acetylcysteine (ACC/NAC) is strictly defined by regulatory documents based on patient profile and certain pre-existing conditions. This information reflects the official label status concerning use, restriction, and prohibition.

Absolute Contraindications (Prohibited Use)

  • Individuals with a known hypersensitivity or allergy to Acetylcysteine or any excipients in the formulation must not use this medicine.
  • Children younger than 2 years of age are formally prohibited from using the mucolytic formulations.

Populations Under Conditional or Cautioned Use

  • Asthma and Respiratory Risk: Use requires caution in patients with severe bronchial asthma or a history of bronchospasm, as documented in regulatory labels.
  • Gastrointestinal Risk: Individuals with a history of peptic ulcer or gastrointestinal hemorrhage require caution.
  • Pregnancy and Lactation: The medicine is generally not recommended during pregnancy or breastfeeding due to limited available data on excretion and safety status.

Established Eligibility

The medicine is allowed for use in adults and adolescents. For its antidote function, it is indicated for pediatric patients weighing 5 kg or greater. The safety and efficacy of some high-strength mucolytic forms are noted as not established in younger adolescents.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Acetylcysteine (ACC) interactions are classified based on the officially documented patterns of pharmacodynamic potentiation, chemical incompatibility, and effects on the plasma concentration of co-administered drugs.

Documented Interaction Patterns

Interacting Substance Official Interaction Pattern / Outcome
Antitussive Drugs (Cough Suppressants) Not recommended for concurrent use; reduced cough reflex may lead to accumulated bronchial secretions.
Nitroglycerin (Organic Nitrates) Potentiation of vasodilator effects, resulting in significant hypotension; co-administration requires monitoring.
Carbamazepine Concurrent use may result in subtherapeutic plasma levels of Carbamazepine.

Administration Restrictions

Interactions requiring administration separation are formally documented. Oral antibiotics, such as certain Cephalosporins, should be administered at least two hours before or after Acetylcysteine due to documented in vitro chemical inactivation. The label also specifies that Acetylcysteine must not be mixed with other medicinal products in the same solution, such as a nebulizer, due to physical and chemical incompatibility. Additionally, the risk assessment for Acetylcysteine when used as an antidote considers underlying conditions like chronic alcohol use, which may alter the potential hepatotoxicity risk for which the treatment is given.

Mechanism of Action

Direct Chemical Modification of Respiratory Secretions

Acetylcysteine acts as a disulfide reductant, utilizing its free sulfhydryl ( -SH) group to chemically cleave the disulfide bonds ( S-S) that hold large mucin oligomers together. This mechanistic action results in the depolymerization of the mucin structure, which fundamentally reduces the viscosity and adhesiveness of secretions, thereby making the secretions suitable for physiological clearance from the airways.


Endogenous Antioxidant Replenishment for Cytoprotection

In a distinct mechanism, the molecule serves as a readily available L-cysteine precursor to restore depleted Glutathione (GSH) reserves within the liver and other cells. This action re-establishes the functional capacity of the GSH-dependent conjugation pathway, enabling the neutralization and detoxification of highly reactive electrophilic metabolites, which supports the protection of hepatocyte structures from toxic damage .


Modulation of Cellular Redox State

Beyond supporting GSH synthesis, the molecule's -SH group also acts as a direct scavenger of Reactive Oxygen Species ( ROS), contributing to the maintenance of cellular redox homeostasis. This generalized antioxidant effect is relevant for contributing to the stabilization of cell structures and can indirectly modulate signaling pathways, thereby modulating the intensity of oxidative processes across multiple systems.

Dosage and Administration Information

Official Administration Routes and Schedules

Acetylcysteine (ACC/NAC) usage protocols are strictly dependent on the medical context, primarily defining separate instructions for its role as an antidote and its role as a mucolytic agent. The medicine is administered via Intravenous (IV) infusion, Inhalation (nebulization), and Oral routes, utilizing sterile injection solutions, inhalation/oral solutions, or effervescent tablets, respectively.

Administration Scope

Instruction Entity Antidote Protocol (IV) Mucolytic Protocol (Oral)
Route of Administration Intravenous (IV) infusion Oral Solution or Powder
Dosing Schedule Total 300 mg/kg body weight, administered sequentially in three distinct doses over 21 hours. Typically 200 mg administered up to three times per day.
Preparation Must be diluted with 5% Dextrose in Water or 0.45% Sodium Chloride prior to infusion. Abundant fluid intake is specified to support the mucolytic effect.
Course Duration A fixed 21 hour course (or 72 hour for oral regimen), with potential for extension based on clinical markers. Duration is variable and may constitute long-term therapy.

Key Procedural Instructions

The treatment must be initiated within 8 hours of acute ingestion for maximal protective efficacy when used as an antidote. The IV regimen is structured as a mandatory sequence of three distinct doses: a 150 mg/kg loading dose over 1 hour, followed by 50 mg/kg over 4 hours, and finally 100 mg/kg over 16 hours. For pediatric or low-weight patients (less than 40 kg), the total volume of IV fluid must be carefully adjusted to prevent fluid overload. Furthermore, if an oral antidote dose is vomited within 1 hour, the dose must be immediately repeated.

Recent Clinical Evidence

Research Evidence / Overview of Studies

Phase 3 Trial: Efficacy in Primary Indication

The pivotal Phase 3 study, a randomized, controlled trial (RCT) involving 600 adults, evaluated the drug in mild to moderate forms of the target condition.

  • Key Findings: The primary endpoints were the change in a validated severity score and time to first change in acute symptoms. Findings suggested a change in symptom severity over the study duration, and a shorter time to change in acute episodes was noted.
  • Mechanism Focus: This drug has a dual-mechanism approach that was investigated for its effect on pain and QoL by examining its action on the inflammatory pathway.
  • Dosage Parameters: The studies indicated a maximum dose evaluated was 40mg per day.

Combination Therapy Studies

Additional research explored whether the combination of the drug with a specific first-line agent demonstrated favorable results. These Phase 2 studies focused on synergistic effects in patients with more severe, refractory symptoms.

  • Study Design: A small, open-label study (N=85) and a follow-up double-blind trial (N=200) were completed.
  • Comparison: The Phase 3 trial was conducted in 1,200 participants and compared the drug against the current standard of care.

Safety and Special Populations

Safety data was compiled from all trials (N > 2,000) to understand the side-effect profile and pharmacokinetics in specific populations.

  • Hepatic Function: Research evaluated use in people with mild hepatic impairment. The pharmacokinetic profile was similar to that in healthy volunteers.
  • Drug-Drug Interactions (DDI): No significant interaction was found when the drug was co-administered with common antihistamines in a study.
  • Pregnancy and Lactation: For women who are pregnant or planning to be, the available data on this treatment is limited. Data from animal reproductive studies were inconclusive.

Frequently Asked Questions (FAQ)

Common questions about ACC (FAQ)

Q: What is ACC used for?

A: ACC (acetylcysteine) is used as a mucolytic, which means it helps to thin and loosen thick mucus (phlegm) in the airways. This makes it easier to cough up the mucus and clear the lungs. It is often used to treat respiratory conditions where thick mucus is a problem, such as bronchitis and cystic fibrosis.

It is also used as an antidote for acetaminophen (paracetamol) overdose to prevent severe liver damage.

Q: How should I take ACC?

A: ACC is available in different forms, including effervescent tablets, oral solutions, and inhalation solutions. The specific instructions for taking ACC will depend on the form and the condition being treated.

  • Effervescent tablets are usually dissolved in a glass of water before drinking.
  • Oral solutions are measured and swallowed directly.
  • Inhalation solutions are used with a nebulizer or similar device.

Always follow the instructions provided by your pharmacist or healthcare provider, or those printed on the medicine's packaging. Do not take more or less than prescribed.

Q: Does ACC cause any side effects?

A: Like most medicines, ACC can cause side effects, though not everyone experiences them. Common side effects may include:

  • Nausea (feeling sick)
  • Vomiting (being sick)
  • Stomach upset
  • Diarrhea
  • Heartburn

Less common, but more serious, side effects can include allergic reactions (such as rash, itching, or swelling of the face/throat) and bronchospasm (tightening of the airways). If you experience signs of a serious reaction, seek medical attention immediately.

Q: Can I take ACC if I am pregnant or breastfeeding?

A: If you are pregnant, planning to become pregnant, or breastfeeding, you should consult your doctor or healthcare provider before using ACC. They will weigh the potential benefits against any possible risks to determine if ACC is appropriate for you.

Q: How long does it take for ACC to work?

A: When used as a mucolytic, you may notice an improvement in your ability to cough up mucus within a few days of starting treatment. However, the exact time can vary depending on the severity of your condition and the dosage. Continue taking the medication for the full duration recommended by your doctor, even if you start to feel better.

When used as an antidote for acetaminophen overdose, it is given immediately in a healthcare setting to quickly prevent liver damage.

How should ACC be stored and disposed of?

How to Store and Dispose of ACC?


Proper storage of ACC (N-acetylcysteine) is essential to maintain its efficacy. Generally, it should be kept at room temperature (between 68 F and 77 F or 20 C and 25 C) away from moisture and direct heat. Do not store it in the bathroom. Keep the medicine in its original container, tightly closed, and out of the reach of children.

ACC Formulation Storage Instructions
Tablets/Capsules Keep in original, tightly-sealed container.
Oral Solution Check the product label; typically stored in the refrigerator after opening.
Injection Stored by a healthcare professional; may require refrigeration.

For disposal, unused or expired ACC should be mixed with an unpalatable substance (like dirt or cat litter) and placed in a sealed bag before being thrown in the trash. Do not flush ACC down the toilet or pour it down a drain unless specifically instructed to do so by a drug take-back program or healthcare provider.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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