Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
Quick facts
- Drug class
- Antidote [EPC], Antidote for Acetaminophen Overdose [EPC], Mucolytic [EPC], Reduction Activity [MoA]
- How it is given
- oral, respiratory (inhalation)
- Type
- human prescription drug
- RxNorm ID
- 307718
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
INDICATIONS AND USAGE Acetylcysteine is indicated as adjuvant therapy for patients with abnormal, viscid, or inspissated mucous secretions in such conditions as: Chronic bronchopulmonary disease (chronic emphysema, emphysema with bronchitis, chronic asthmatic bronchitis, tuberculosis, bronchiectasis and primary amyloidosis of the lung) Acute bronchopulmonary disease (pneumonia, bronchitis, tracheobronchitis) Pulmonary complications of cystic fibrosis Tracheostomy care Pulmonary complications associated with surgery Use during anesthesia Post-traumatic chest conditions Atelectasis due to mucous obstruction Diagnostic bronchial studies (bronchograms, bronchospirometry, and bronchial wedge catheterization) INDICATIONS AND USAGE Acetylcysteine, administered orally, is indicated as an antidote to prevent or lessen hepatic injury which may occur following the ingestion of a potentially hepatotoxic quantity of acetaminophen. It is essential to initiate treatment as soon as possible after the overdose and, in any case, within 24 hours of ingestion.
About this medicine
DESCRIPTION Acetylcysteine solution is for inhalation (mucolytic agent) or oral administration (acetaminophen antidote), and available as sterile, unpreserved solutions (not for injection). Acetylcysteine is the N-acetyl derivative of the naturally occurring amino acid, L-cysteine. Chemically, it is N-acetyl-L-cysteine. The compound is a white crystalline powder which melts at 104°−110°C and has a very slight odor. The structural formula for acetylcysteine is as follows: Molecular weight: 163.19 Each mL of the 10% solution contains acetylcysteine 100 mg; edetate disodium, dihydrate 0.25 mg. Each mL of the 20% solution contains acetylcysteine 200 mg; edetate disodium, dihydrate 0.5 mg. The solutions also contain sodium hydroxide and may contain hydrochloric acid for pH adjustment, pH 7.0 (6.0 to 7.5). Acetylcysteine Solution, USP is oxygen sensitive. Acetylcysteine As A Mucolytic Agent structural formula acetylcysteine
Who should not take it
CONTRAINDICATIONS Acetylcysteine is contraindicated in those patients who are sensitive to it. CONTRAINDICATIONS There are no contraindications to oral administration of acetylcysteine in the treatment of acetaminophen overdose.
Warnings
WARNINGS After proper administration of acetylcysteine, an increased volume of liquified bronchial secretions may occur. When cough is inadequate, the open airway must be maintained by mechanical suction if necessary. When there is a mechanical block due to foreign body or local accumulation, the airway should be cleared by endotracheal aspiration, with or without bronchoscopy. Asthmatics under treatment with acetylcysteine should be watched carefully. Most patients with bronchospasm are quickly relieved by the use of a bronchodilator given by nebulization. If bronchospasm progresses, this medication should be discontinued immediately. WARNINGS Generalized urticaria has been observed rarely in patients receiving oral acetylcysteine for acetaminophen overdose. If this occurs or other allergic symptoms appear, treatment with acetylcysteine should be discontinued unless it is deemed essential and the allergic symptoms can be otherwise controlled. If encephalopathy due to hepatic failure becomes evident, acetylcysteine treatment should be discontinued to avoid further administration of nitrogenous substances. There are no data indicating that acetylcysteine adversely influences hepatic failure, but this remains a theoretical possibility.
Reported side effects
ADVERSE REACTIONS Adverse effects have included stomatitis, nausea, vomiting, fever, rhinorrhea, drowsiness, clamminess, chest tightness, and bronchoconstriction. Clinically overt acetylcysteine induced bronchospasm occurs infrequently and unpredictably even in patients with asthmatic bronchitis or bronchitis complicating bronchial asthma. Acquired sensitization to acetylcysteine have been reported rarely. Reports of sensitization in patients have not been confirmed by patch testing. Sensitization has been confirmed in several inhalation therapists who reported a history of dermal eruptions after frequent and extended exposure to acetylcysteine. Reports of irritation to the tracheal and bronchial tracts have been received and although hemoptysis has occurred in patients receiving acetylcysteine such findings are not uncommon in patients with bronchopulmonary disease and a causal relationship has not been established. ADVERSE REACTIONS Oral administration of acetylcysteine, especially in the large doses needed to treat acetaminophen overdose, may result in nausea, vomiting and other gastrointestinal symptoms. Rash with or without mild fever has been observed rarely.
Interactions with other medicines
Drug Interactions Drug stability and safety of acetylcysteine when mixed with other drugs in a nebulizer have not been established.
Before you take anything new
Tell your pharmacist or doctor about every medicine you take — including ones bought without a prescription, herbal products and supplements. Interactions are one of the most common avoidable causes of harm from medicines, and a pharmacist can check your full list in a couple of minutes.
This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 22 May 2026. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.