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Acetylcysteine (NAC)

Prescription
Antidote (glutathione precursor) / Mucolytic
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
4 available
Interactions
1 documented
Formulations
2

Mechanism of action

Provides cysteine as a precursor for hepatic glutathione synthesis; restores glutathione stores depleted by acetaminophen (paracetamol) toxicity, preventing formation of toxic NAPQI metabolite; also has mucolytic action by breaking disulfide bonds in mucus glycoproteins

At a glance

Class
Antidote (glutathione precursor) / Mucolytic
Schedule
Prescription
Storage
Below 25°C; opened vials stable 96 hours refrigerated

Dosing

🐕

Dog

Acetaminophen toxicity, hepatoprotection
Dose
140 mg/kg
Route
IV (slow), PO
Frequency
Loading dose 140mg/kg, then 70mg/kg Q4H for 5–7 additional doses
Max dose
140 mg/kg loading/dose; 0 mg/kg loading/day
Duration: 24–72 hours or until liver enzymes stabilize
🐈

Cat

Acetaminophen toxicity (cats are EXTREMELY sensitive)
Dose
140 mg/kg
Route
IV (slow), PO
Frequency
Loading dose 140mg/kg, then 70mg/kg Q6H for 7 additional doses
Max dose
140 mg/kg loading/dose; 0 mg/kg loading/day
Duration: 48–72 hours; cats require aggressive treatment

Formulations

🧴

Solution — 1

Strength
20% (200mg/mL)
Available in India
💊

Effervescent tablet — 1

Strength
600mg
Available in India

Storage

Below 25°C; opened vials stable 96 hours refrigerated

Safety

Use with caution

  • Asthma or bronchospasm
    IV NAC can rarely cause bronchospasm or anaphylactoid reactions

Adverse effects

Common
Vomiting (oral form due to taste/smell)
Nausea
Serious
Anaphylactoid reaction (IV)
Bronchospasm

Monitoring parameters

Hepatic enzymes (ALT, AST)BilirubinMethemoglobin levels (cats)Coagulation parametersPCV

Interactions

Major — 1

Activated Charcoal
major
Charcoal adsorbs NAC in the GI tract, rendering oral NAC ineffective for acetaminophen toxicity treatment.
Management: If both needed: give charcoal first for toxin adsorption, then give NAC IV (bypasses GI). If only oral NAC available, wait 1-2h after charcoal or give NAC at increased dose.

Brands

International

Mucomyst
Mead Johnson
Acetadote
Cumberland Pharmaceuticals

India

Mucinac
Cipla
ACC
Samarth Pharma

FAQs

Frequently asked questions

›What is Acetylcysteine (NAC)?
Acetylcysteine (NAC) is a antidote (glutathione precursor) / mucolytic used in pets. Provides cysteine as a precursor for hepatic glutathione synthesis; restores glutathione stores depleted by acetaminophen (paracetamol) toxicity, preventing formation of toxic NAPQI metabolite; also has mucolytic action by breaking disulfide bonds in mucus glycoproteins
›What is Acetylcysteine (NAC) used for in pets?
Acetylcysteine (NAC) is used in veterinary medicine for: Acetaminophen toxicity, hepatoprotection; Acetaminophen toxicity (cats are EXTREMELY sensitive).
›What is the Acetylcysteine (NAC) dose for dogs?
For dogs, Acetylcysteine (NAC) is typically dosed as follows — Acetaminophen toxicity, hepatoprotection: 140 mg/kg IV (slow)/PO Loading dose 140mg/kg, then 70mg/kg Q4H for 5–7 additional doses. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Acetylcysteine (NAC) dose for cats?
For cats, Acetylcysteine (NAC) is typically dosed as follows — Acetaminophen toxicity (cats are EXTREMELY sensitive): 140 mg/kg IV (slow)/PO Loading dose 140mg/kg, then 70mg/kg Q6H for 7 additional doses. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Acetylcysteine (NAC)?
Common: Vomiting (oral form due to taste/smell), Nausea. Serious (call your vet immediately): Anaphylactoid reaction (IV), Bronchospasm.
›Does Acetylcysteine (NAC) need a prescription?
Yes. Acetylcysteine (NAC) is a prescription medication and should only be administered under veterinary supervision.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

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