Comparison
N-Acetyl Cysteine vs Nicotinamide Riboside
Side-by-side of N-Acetyl Cysteine and Nicotinamide Riboside. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
N-Acetyl Cysteine
NAC supplement benefits cover glutathione synthesis, liver and antioxidant support, and hangover recovery. Evidence strongest at 1200-2400 mg/day.
Nicotinamide Riboside
Nicotinamide riboside (NR) is the most-studied NAD+ precursor in humans. Sold as Niagen by Chromadex; raises plasma NAD+ 30-60% at 250-1,000 mg/day.
Effects at a glance
N-Acetyl Cysteine
- •Replenishes intracellular glutathione by supplying cysteine, the rate-limiting amino acid for synthesis
- •First-line antidote for acetaminophen toxicity, restoring hepatic glutathione before fulminant injury occurs
- •Reduces sputum viscosity in chronic bronchitis and COPD at 600 to 1200 mg/day over months
- •Modest symptom reductions in OCD and trichotillomania at 1200 to 2400 mg/day across small RCTs
- •Mixed evidence for psychiatric adjunct use in bipolar depression and schizophrenia negative symptoms
- •Inhaled forms can trigger bronchospasm in active asthma; oral use is the standard biohacker route
Nicotinamide Riboside
- •Most-studied NAD+ precursor in human trials; the original Niagen formulation by Chromadex
- •Plasma NAD+ rises 30-60% at 250-1,000 mg/day across multiple human PK trials
- •Martens 2018 reported reduced BP and arterial stiffness at 500 mg/day for 6 weeks
- •Dollerup 2018 found no insulin sensitivity change despite plasma NAD+ rise
- •Tissue NAD+ rise inconsistent; hard clinical endpoints not yet measured
- •Larger human safety database than NMN; comparable mechanistic effects
Side-by-side
| Attribute | N-Acetyl Cysteine | Nicotinamide Riboside |
|---|---|---|
| Category | supplement | supplement |
| Also known as | NAC | NR, Niagen, nicotinamide riboside chloride |
| Half-life (hr) ↗ | 5.6 | 8 |
| Typical dose (mg) ↗ | 1200 | 500 |
| Dosing frequency | 1 to 3 times daily, split dosing preferred | daily, typically morning |
| Routes | oral, iv | oral |
| Onset (hr) | 1 | 1 |
| Peak (hr) | 2 | 4 |
| Molecular weight | 163.19 | 255.25 |
| Molecular formula | C5H9NO3S | C11H15N2O5 |
| Mechanism | Deacetylated to cysteine, the rate-limiting precursor for glutathione synthesis; also directly scavenges reactive oxygen species and modulates glutamate signaling. | NAD+ precursor via salvage pathway. Phosphorylated to NMN by nicotinamide riboside kinase (NRK), then converted to NAD+. Substrate for sirtuins, PARPs, and CD38. |
| Legal status | OTC in most jurisdictions; restricted periods in US history (FDA reclassified 2022) | OTC dietary supplement |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement (US, post-2022); Rx indications also exist (acetaminophen overdose, mucolytic) | OTC supplement |
| Pregnancy | Used clinically in pregnancy for specific indications; consult clinician | Insufficient data at supplement doses |
| CAS | 616-91-1 | 1341-23-7 |
| PubChem CID | 12035 | 439924 |
| Wikidata | Q413299 | Q3343054 |
Safety profile
N-Acetyl Cysteine
Common side effects
- sulfur-like taste or odor
- nausea
- flatulence
- diarrhea
Contraindications
- active asthma attack (inhaled form can trigger bronchospasm)
- known NAC hypersensitivity
Interactions
- nitroglycerin: potentiates vasodilation, risk of hypotension and headache(moderate)
- activated charcoal: reduces NAC absorption when used for acetaminophen overdose(moderate)
- anticoagulants: theoretical additive antiplatelet effect at high doses(minor)
Nicotinamide Riboside
Common side effects
- mild GI upset (rare)
- headache (rare)
Contraindications
- pregnancy / lactation (insufficient data)
- active cancer (theoretical, no contraindicating data)
Interactions
- pterostilbene: complementary sirtuin pathway (Basis combination)(minor)
- TMG (trimethylglycine): methylation support during high NAD+ precursor dosing(minor)
Which Should You Take?
Nicotinamide Riboside comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-A outcome catalogued. N-Acetyl Cysteine is the right call when one of the conditionals below applies.
- → If your priority is post-training recovery, pick N-Acetyl Cysteine.
- → If your priority is liver function, pick N-Acetyl Cysteine.
- → If your priority is energy and stamina, pick Nicotinamide Riboside.
- → If your priority is metabolic health and glucose control, pick Nicotinamide Riboside.
Default choice: Nicotinamide Riboside. Lower friction to source, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for N-Acetyl Cysteine only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between N-Acetyl Cysteine and Nicotinamide Riboside?
N-Acetyl Cysteine and Nicotinamide Riboside differ in category (supplement vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, N-Acetyl Cysteine or Nicotinamide Riboside?
N-Acetyl Cysteine half-life is 5.6 hours; Nicotinamide Riboside half-life is 8 hours.
Can you stack N-Acetyl Cysteine with Nicotinamide Riboside?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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