NAC (N-Acetylcysteine)

NAC scores 8.0–8.5/10, Strong recommend: a cheap, broad, deeply-evidenced glutathione precursor with a genuinely life-saving core use and a benign safety record. The practical verdict is that almost anyone can take it safely, but the size of the benefit depends entirely on why you are taking it. It is essential and curative in acetaminophen overdose, reliably useful as a COPD mucolytic, and a reasonable clinician-supervised adjunct for OCD, hair-pulling, or addiction relapse. For a healthy person chasing a felt daily lift, it is a quiet biochemical support rather than something you notice. The strong tier is justified by the breadth, the safety, and the price, tempered by repeated non-replication in psychiatry and renal use.

✅ Best for: People who want one inexpensive, foundational antioxidant that doubles as respiratory and liver-detox support. Anyone with chronic mucus-heavy lungs or COPD, where the mucolytic benefit is Cochrane-backed. People exploring NAC as a clinician-supervised adjunct for OCD, trichotillomania, or substance-use relapse, especially adolescents or already-abstinent users where the signal is strongest. Women with PCOS-related subfertility using it alongside clomiphene. Biohackers who want the glutathione substrate that powers the GlyNAC longevity stack at a few cents a day.

❌ Avoid if: You have reactive airways or asthma and are considering the inhaled mucolytic form, which can trigger bronchospasm; the oral capsule is fine. You take anticoagulants or antiplatelets, or have surgery scheduled within two weeks, without clinician clearance, given NAC's mild antiplatelet activity. You are pregnant or lactating and using it outside medical guidance. You expect it to prevent contrast-induced kidney injury, which the large ACT and PRESERVE trials show it does not. You want a dramatic, same-day, stimulant-like effect from a subtle metabolic precursor.