Major Uses

Acetylcysteine is used for a variety of medical issues among species ranging from dogs and cats to horses. It is most commonly used as a mucolytic agent for patients with difficulty expelling mucus, an oral antidote for Tylenol (acetaminophen) overdose, and treating dry eye (Keratoconjunctivitis Sicca) in dogs and cats.

When used as a mucolytic agent, Acetylcysteine breaks down and dissolves mucus by thinning the mucus' consistency, allowing the animal to disrupt and dislodge the mucus.

As an antidote for Tylenol (acetaminophen) overdose, Acetylcysteine reduces the severity of liver damage. This medication is a sulfurous amino acid, which directly binds with acetaminophen metabolites and expedites their elimination.

Heavy discharge caused by dry eye (Keratoconjunctivitis Sicca) can be reduced or eliminated when using Acetylcysteine.

Common Precautions

When administered through an inhaler, the aerosolized Acetylcysteine may cause bronchial receptors to become irritated and constricted. Its use in this manner should be followed by bronchodilator therapy to relieve irritation and allow easier breathing. Animals with asthma, or other breathing conditions which may cause lung spasms, should be monitored very carefully while using this medication in its aerosolized form.

When used orally to treat Tylenol (acetaminophen) overdose, this medication typically causes vomiting and upset stomach. The animal should be closely monitored to ensure the medication stays in the stomach and therefore metabolized.

This medication should not be administered to animals with a known allergy or hypersensitivity to Acetylcysteine. Although this medication is relatively safe and side effects are rare, if hives or difficulty breathing are noticed, you should contact your veterinarian.


Unopened vials of Acetylcysteine should be stored at room temperatures ranging from 68 to 77 degrees Fahrenheit (between 20 to 25 degrees Celsius). If stored properly and unopened within these temperature ranges, this medication has a shelf-life of three years.

Opened containers must be kept refrigerated, not frozen, and should be used within 96 hours or four days. Care should be taken to keep this medication out of reach from children and pets.


Acetylcysteine is available in oral and injectable form. Giving Acetylcysteine in an injectable form bypasses the risk of losing the medication from stomach upset or nausea, which is a common side effect when given orally.

A typical dose consists of an initial dose followed by multiple maintenance doses. The first dose is 140mg/kg of a 5% solution injected intravenously or by mouth (diluted in a 5% dextrose or sterile water solution). The initial dose is followed by 70mg/kg maintenance doses, by mouth, four times a day for seven or more treatments.

If a dose is missed, a pet's owner or veterinarian should administer the missed dose as soon as possible. If the next dose is closer in time than the forgotten dose, the missed dose can be skipped and the care taker should continue with regular doses thereafter.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.