Clinical Information
Use exactly as directed by your healthcare provider. Your provider will decide the dose, how fast it is given, and how many doses you need. Do not self-inject unless you have been fully trained. If you miss a scheduled dose, contact your healthcare provider right away for guidance. Never double up on doses.
After injection, NAC quickly breaks down in the body and turns into cysteine, a building block for glutathione. Glutathione is a key antioxidant that neutralizes harmful molecules and helps protect liver cells. NAC also breaks chemical bonds in thick mucus, making it easier to clear from the lungs. The medicine starts working within 30–60 minutes and its effects last about 4–6 hours, depending on the dose and your kidney function.
Do not use if you have ever had a severe allergic reaction to N-Acetyl-Cysteine. Do not use if the solution is discolored, cloudy, or contains particles. Avoid use during active gastrointestinal bleeding unless your provider determines the benefits outweigh the risks. Tell your provider if you have asthma, stomach ulcers, or are pregnant or breastfeeding so they can decide if this medication is right for you.
• Nitroglycerin or isosorbide (used for chest pain): may increase risk of low blood pressure and headache.
• Activated charcoal (used for overdose treatment): can lower how much NAC your body absorbs if given at the same time.
• Carbamazepine and other seizure medicines: NAC may slightly reduce their blood levels.
• Antitussive cough syrups: added mucus thinning can lead to more coughing.
Always give your provider a full list of prescriptions, over-the-counter drugs, vitamins, and herbal supplements. Limit alcohol because it strains the liver you are trying to protect.
Very common (more than 1 in 10 people): nausea, vomiting, bad sulfur-like smell or taste during infusion—these usually improve after the dose finishes.
Common (1–10 in 100 people): flushing, sweating, mild drop in blood pressure, fast heartbeat, rash or itching.
Uncommon (1–10 in 1,000 people): bronchospasm (wheezing), especially in asthma patients; fever; headache.
Rare but serious: anaphylactoid reactions with swelling of face, lips, or throat, severe hives, chest tightness, or trouble breathing. These usually occur within the first hour of infusion and require immediate medical care. Most side effects stop when the infusion rate is slowed or the medicine is stopped.
Store in the original sealed vial at room temperature 68-77 °F (20-25 °C). Brief exposure to 59-86 °F (15-30 °C) is allowed. Keep away from excessive heat, freezing, and direct sunlight. Do not refrigerate or freeze. Once the vial is punctured, label the date and keep tightly closed; discard any unused solution 30 days after first puncture or sooner if it becomes cloudy. Dispose of unused or expired drug through a pharmacy take-back program or follow local guidelines—do not pour down the drain.
Frequently Asked Questions
Q:What is this injection used for?
A:Doctors use N-Acetyl-Cysteine to help protect the liver after an acetaminophen (Tylenol) overdose and to thin thick mucus in the lungs. Your provider will tell you the exact reason you are receiving it.
Q:How soon will it start working?
A:You may feel relief in breathing within about an hour if it is used for mucus thinning. For liver protection, blood tests over the next 24 hours will show how well it is working even if you do not feel different right away.
Q:Can I drive after receiving NAC?
A:Some people feel light-headed or nauseated during or right after the infusion. Wait until you know how you respond before driving or operating machinery.
Q:Is it safe during pregnancy?
A:Small studies suggest NAC is generally safe in pregnancy, but it should only be used if clearly needed. Tell your provider if you are pregnant or may become pregnant so they can weigh the benefits and risks.
Q:What should I do if the injection site hurts or looks red?
A:Mild discomfort is common, but increasing pain, redness, or swelling can signal irritation or infection. Contact your healthcare team right away if you notice these signs.
Q:How should I store the vial once it has been opened?
A:Keep the punctured vial tightly closed at room temperature and use sterile technique each time you draw a dose. Throw away any leftover medicine 30 days after first opening or sooner if it changes color or becomes cloudy.
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