Are N-Acetyl Cysteine and Acetyl Cysteine the Same?
Yes, N-acetylcysteine (NAC) and acetylcysteine are the same compound—they are simply different names for the identical chemical substance. 1, 2
Nomenclature and Chemical Identity
The FDA drug label confirms that "acetylcysteine is the nonproprietary name for the N-acetyl derivative of the naturally occurring amino acid, L-cysteine" with the chemical designation N-acetyl-L-cysteine. 1
Multiple naming conventions exist for this single compound, all referring to the same substance: 2
- N-acetyl-cysteine
- N-acetylcysteine
- N-acetyl cysteine
- N-acetyl-L-cysteine
- Acetylcysteine
All of these designations are abbreviated as NAC and represent the same molecular structure (C5H9NO3S, molecular weight 163.19). 1, 2
Clinical Context
The interchangeable terminology appears consistently across medical literature and guidelines: 3
- COPD guidelines refer to both "N-acetylcysteine" and "NAC" when discussing the same mucolytic agent 3
- Chemotherapy neuropathy guidelines use "N-acetylcysteine (NAC)" and "acetylcysteine (NAC)" interchangeably 3
- Cystic fibrosis guidelines use "N-acetylcysteine (NAC)" consistently 3
- Acetaminophen overdose protocols from the American Association for the Study of Liver Diseases and American College of Emergency Physicians use "NAC" and "N-acetylcysteine" synonymously 4
Common Pitfall
Do not confuse nomenclature variations as indicating different medications—whether a prescription, guideline, or research paper uses "acetylcysteine," "N-acetylcysteine," or any hyphenated variant, they all refer to the identical therapeutic agent. 1, 2