acetylcysteine at a glance
Medicine class
Mucolytic; intravenous acetylcysteine is also an antidote.
Licensed roles
Thick respiratory mucus, paracetamol overdose and dry eye associated with abnormal mucus or deficient tears.
What is acetylcysteine used for?
Selected products are licensed for:
Making thick bronchial mucus easier to cough up.
Hospital treatment of paracetamol overdose where treatment criteria are met.
Relieving dry eye associated with deficient tears or abnormal ocular mucus.
How does acetylcysteine work?
Acetylcysteine breaks chemical links within mucus, making it thinner. In paracetamol poisoning, it replenishes glutathione and helps neutralise the toxic metabolite NAPQI. In the eye, this mucus-thinning action is combined with lubrication from hypromellose.
acetylcysteine preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 200 mg/mL
Effervescent tablet
Route: Oral
Strengths: 600 mg
Oral solution
Route: Oral
Strengths: 200 mg
Injection
Route: Parenteral
Strengths: 200 mg/mL
How to take acetylcysteine
Use the formulation exactly as directed because instructions differ between products.
Dissolve oral powder completely in water immediately before drinking, then drink the entire mixture.
Fully dissolve effervescent tablets in water and drink immediately; do not swallow them whole.
Intravenous acetylcysteine is prepared and monitored by hospital staff.
Remove soft contact lenses before using Ilube eye drops. Do not drive until any blurred vision has cleared.
acetylcysteine side effects
Common or expected effects
- Feeling sick, vomiting, diarrhoea or abdominal discomfort with oral treatment
- Headache, itching, rash or fever
- Flushing, nausea, vomiting or rash during intravenous treatment
- Temporary eye redness, itching, irritation or blurred vision with eye drops
Get urgent medical advice
- Severe allergic or anaphylactoid reaction, including breathing difficulty, swelling or collapse
- Bronchospasm or worsening wheeze
- Severe blistering or peeling skin and mucosal lesions
- Severe bleeding
- Fluid overload, low sodium or seizures during intravenous treatment, particularly in susceptible patients
acetylcysteine in pregnancy
Evidence for routine oral or ocular use during pregnancy is limited, so prescriber assessment is needed. Paracetamol overdose during pregnancy requires urgent hospital assessment; acetylcysteine may be used when indicated, and delaying treatment may worsen outcomes.
acetylcysteine interactions
Relevant interactions depend on the formulation and indication.
Cough suppressants
Reducing the cough reflex may allow loosened secretions to accumulate; combined use requires clinical review.
Oral antibiotics
Direct contact may reduce the activity of some antibiotics; ask a pharmacist for administration advice.
Common questions about acetylcysteine
Answers are fully visible for fast scanning and source review.
Is acetylcysteine the same as NAC?
Yes. NAC and N-acetylcysteine are alternative names for acetylcysteine.
Why does acetylcysteine smell like rotten eggs?
Its sulphur-containing structure can cause this characteristic smell, particularly when an oral sachet is opened. This alone does not mean it is spoiled.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.