NAC (N-acetylcysteine)
C5H9NO3S
A modified form of the amino acid cysteine. Small molecule, one sulfur atom.
Evidence current to September 2026
What it's pushed for
What the research shows
A systematic review published in July 2026 found only six clinical studies in endometriosis. Outside of surgery, NAC was linked to less pain, less NSAID use, and endometriomas shrinking or staying stable.
The results aren't uniform. The one randomized trial after surgery found NAC added no benefit over continuous birth control pills. Fertility findings were early.
Myth vs. fact
Myth"NAC shrinks endometriosis."
FactA few small studies saw endometrioma changes, but there are no large placebo-controlled trials yet. It's a reasonable question to bring to a gynecologist, not a replacement for treatment.
The detail most people miss
NAC sits in a legal gray area. The FDA considers it a drug first, but since 2022 has said it won't object to NAC being sold as a supplement. That's why it sometimes disappears from retailers.
Who should check with a clinician first
Anyone on prescription medications, especially heart or blood pressure medicines. A pharmacist can check this quickly.
What to look for on the label
Look for plain NAC with the amount stated. A sulfur smell is normal. Be skeptical of "detox" blends that bury NAC among many other ingredients.
How to read any supplement labelSources
This guide is for education, not medical advice. Supplements can interact with medications and health conditions. Talk with your clinician or pharmacist before starting, stopping, or changing anything. The Lily Perspective earns no income from any supplement brand or retailer.