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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

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

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 →

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

Educational reference only

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.

Educational reference only

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.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database

Related medicines

Other medicines in the same class (Antidote).

Ethanol (Medical Grade)

Competitive substrate for alcohol dehydrogenase with higher affinity than methanol or ethylene glycol, preventing their metabolism to toxic metabolites (formic acid from methanol; glycolate/oxalate from ethylene glycol). Parent compounds are excreted renally.

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