NAC
TL;DR
Precursor to Glutathione, the body's 'Master Antioxidant'
High evidence for liver protection and clearing lung mucus
Moderate evidence for reducing obsessive-compulsive behaviors and 'brain fog'
Uniquely strong safety profile; used in hospitals for Tylenol overdoses
Affordable: ~$10-20/month
Best for: Liver health, lung/respiratory support, OCD/impulse control
What it is
N-Acetyl Cysteine (NAC) is a stable form of the amino acid cysteine. Its primary job is to replenish the body's stores of glutathione. Because glutathione is the main defense against 'oxidative stress' in the liver, lungs, and brain, NAC is a powerful general-purpose health optimizer.
What the research says
Multiple RCTs for noise-induced hearing loss prevention. Some evidence for existing tinnitus via glutamate modulation and antioxidant protection of cochlear hair cells.
NAC is the 'gold standard' for liver rescue. Hospitals. It is the primary treatment for acetaminophen (Tylenol) poisoning because it prevents liver failure by rapidly restoring glutathione. Fatty Liver. Emerging research shows it can help reduce liver enzymes and inflammation in NAFLD.
NAC helps 'quiet' an over-excited brain. Evidence. Studies suggest NAC can reduce obsessive-compulsive symptoms, hair-pulling, and addictive cravings by modulating glutamate levels. Neuroprotection. By reducing brain inflammation, it acts as a secondary shield against the oxidative damage that leads to dementia.
NAC on Amazon
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Safety
Very safe. The most common side effect is 'sulfur-smelling' breath or mild GI upset. At very high doses, it can thin the mucus in the stomach too much, potentially aggravating ulcers.
Interactions
- Nitroglycerin: May increase the risk of low blood pressure and headaches.
Dosing
For Liver/General Support: 600-1,200 mg daily. For Psychiatric Support (OCD): Up to 2,400 mg daily. Timing: Take with or without food.
Cost
Affordable. $10-20 per month.
The bottom line
NAC is a 'clean-up' supplement. It's one of the best ways to support your liver and lungs while giving your brain an extra layer of antioxidant protection.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.