Acetylcysteine Is a Medication Used to Treat Acetaminophen Overdose and to Thin Mucus in Lung Conditions

Acetylcysteine (N-Acetylcysteine, commonly called NAC) is a medication that serves two primary roles: it's a life-saving antidote for acetaminophen (Tylenol) poisoning and a mucolytic that breaks up thick mucus in people with respiratory conditions. It's been around for decades, is available as a generic, and continues to be one of the most versatile medications in modern medicine.

Here's everything you need to know about Acetylcysteine in 2026 — from what it treats to how much it costs.

What Is Acetylcysteine?

Acetylcysteine is classified as both an antidote and a mucolytic agent. It's available under several brand names:

• Acetadote — the IV formulation made by Cumberland Pharmaceuticals
• Mucomyst — the inhalation formulation
• Fluimucil — available in some countries outside the US

Generic versions are manufactured by multiple companies including Fresenius Kabi, American Regent, and Somerset Therapeutics. Acetylcysteine is not a controlled substance — it has no DEA schedule and no abuse potential.

The drug was first approved by the FDA for mucolytic use in the 1960s and later gained approval as an acetaminophen overdose antidote. It remains one of the most widely used emergency medications worldwide.

What Is Acetylcysteine Used For?

FDA-Approved Uses

• Acetaminophen overdose — Acetylcysteine is the standard antidote for Tylenol poisoning. When someone takes too much acetaminophen, a toxic byproduct called NAPQI builds up and destroys liver cells. Acetylcysteine replenishes your body's glutathione — the antioxidant that neutralizes NAPQI — and can prevent liver failure if given within 8–10 hours of the overdose.
• Mucolytic therapy — For people with thick, sticky mucus from conditions like cystic fibrosis, bronchitis, pneumonia, or COPD, Acetylcysteine breaks apart the mucus so it's easier to cough up and clear. It's delivered by nebulizer as an inhalation solution.
• Diagnostic bronchoscopy support — Used to help clear mucus plugs before or during bronchoscopy procedures.

Off-Label Uses

Doctors also prescribe Acetylcysteine for several conditions that aren't on the official FDA label:

• Acute liver failure not caused by acetaminophen
• Prevention of contrast-induced kidney damage before CT scans or other imaging
• Antioxidant supplementation to prevent COPD flare-ups
• Adjunct treatment for psychiatric conditions (schizophrenia, bipolar disorder, OCD, depression)
• Dry eye treatment (topical form)

How Is Acetylcysteine Taken?

Acetylcysteine comes in several forms, and how you take it depends on why you need it:

IV (Intravenous) — For Acetaminophen Overdose

This is given in a hospital by healthcare professionals. The standard protocol involves three separate infusions over approximately 21 hours:

1. Loading dose: 150 mg/kg over 60 minutes
2. Second dose: 50 mg/kg over 4 hours
3. Third dose: 100 mg/kg over 16 hours

Oral — For Acetaminophen Overdose (Alternative to IV)

If IV isn't available, the oral protocol is: 140 mg/kg as a loading dose, followed by 70 mg/kg every 4 hours for 17 additional doses (72 hours total). The oral solution tastes and smells strongly of sulfur — mixing it with cola or another soft drink makes it much more tolerable.

Inhalation — For Mucus Clearance

Nebulized using the 10% or 20% solution:

• 10% solution: 6–10 mL nebulized 3–4 times daily
• 20% solution: 3–5 mL nebulized 3–4 times daily

Oral Capsules/Tablets — As a Supplement

NAC is also available as oral capsules (500 mg or 600 mg) and tablets (600 mg). Typical supplemental doses range from 600–1,800 mg daily, taken with or without food.

For a deeper look at how the drug works in your body, see our guide to Acetylcysteine's mechanism of action.

Who Should Not Take Acetylcysteine?

Acetylcysteine is contraindicated or should be used with caution in the following groups:

• People with a known allergy to Acetylcysteine — Anaphylactoid reactions are possible, especially with the IV form.
• Asthma or reactive airway disease — Inhaled Acetylcysteine can trigger bronchospasm. A bronchodilator should be used alongside it, and close monitoring is essential.
• Peptic ulcer disease or esophageal varices — The oral form may irritate the GI tract.
• Heart failure or sodium-restricted diets — Some formulations contain sodium that may be relevant for these patients.

For a detailed breakdown of side effects and when to seek help, read our Acetylcysteine side effects guide.

How Much Does Acetylcysteine Cost?

Acetylcysteine is available as a generic, which keeps prices relatively affordable:

• Inhalation solution 10%: $14–$37 for 30–100 mL
• Inhalation solution 20%: $22–$80 for 90–100 mL
• IV solution 20%: $101–$206 for 120 mL (typically covered under hospital benefits)
• Oral NAC capsules (600 mg): $10–$25 for 60–100 capsules

Most insurance plans cover the prescription forms. Medicare Part B covers it when administered in a clinical setting, and Part D may cover outpatient prescriptions. The oral supplement form (OTC capsules) is generally not covered by insurance.

There are no manufacturer copay cards for Acetylcysteine, but discount cards from GoodRx, SingleCare, and RxSaver can significantly reduce out-of-pocket costs. For more ways to save, check our complete savings guide.

Final Thoughts

Acetylcysteine is a proven, versatile medication that's been saving lives and helping people breathe easier for over 60 years. Whether you need it for an emergency (acetaminophen overdose), a chronic lung condition, or one of its many off-label uses, it's generally affordable and available.

If you're looking for Acetylcysteine at a pharmacy near you, Medfinder can help you find it in stock and compare prices.