Comparison
N-Acetyl Cysteine vs TB-500
Side-by-side of N-Acetyl Cysteine and TB-500. 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.
TB-500
TB-500 peptide, a 17-aa thymosin beta-4 fragment. Preclinical tendon and wound healing via actin sequestration. Typical dosage 2 to 5 mg weekly. No human RCTs.
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
TB-500
- •17-amino-acid fragment of endogenous Thymosin Beta-4, an actin-sequestering peptide
- •Preclinical models show accelerated tendon, ligament, and dermal wound healing
- •Equine veterinary use for soft-tissue injury is the most documented real-world application
- •Anecdotal human protocols use 2 to 5 mg twice weekly subcutaneously for 4 to 6 weeks
- •WADA banned under S2 (peptide hormones, growth factors) since 2018
- •No completed phase II or III human RCTs as of 2026; long-term safety unestablished
Side-by-side
| Attribute | N-Acetyl Cysteine | TB-500 |
|---|---|---|
| Category | supplement | peptide |
| Also known as | NAC | Thymosin Beta-4 fragment, TB4-Frag, Thymosin Beta 4 |
| Half-life (hr) ↗ | 5.6 | 2 |
| Typical dose (mg) ↗ | 1200 | 2.5 |
| Dosing frequency | 1 to 3 times daily, split dosing preferred | 2x weekly (anecdotal protocols) |
| Routes | oral, iv | subcutaneous, intramuscular |
| Onset (hr) | 1 | - |
| Peak (hr) | 2 | - |
| Molecular weight | 163.19 | 4963.4 |
| Molecular formula | C5H9NO3S | C212H350N56O78S |
| Mechanism | Deacetylated to cysteine, the rate-limiting precursor for glutathione synthesis; also directly scavenges reactive oxygen species and modulates glutamate signaling. | Sequesters G-actin monomers, modulates cell migration and angiogenesis, and upregulates VEGF and myosin transcription. Promotes endothelial differentiation and stem-cell migration to injury sites in preclinical models. |
| Legal status | OTC in most jurisdictions; restricted periods in US history (FDA reclassified 2022) | Not FDA approved; research-use-only grey market; banned by WADA |
| WADA status | allowed | banned |
| DEA / Rx | OTC supplement (US, post-2022); Rx indications also exist (acetaminophen overdose, mucolytic) | Not FDA approved; not scheduled; research-chemical status |
| Pregnancy | Used clinically in pregnancy for specific indications; consult clinician | Insufficient data |
| CAS | 616-91-1 | 885340-08-9 |
| PubChem CID | 12035 | 62707662 |
| Wikidata | Q413299 | Q7799921 |
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)
TB-500
Common side effects
- injection-site irritation
- fatigue (anecdotal)
- lethargy in early dosing (anecdotal)
Contraindications
- pregnancy
- active malignancy (theoretical angiogenic concern)
- no established human safety profile
Interactions
- BPC-157: Frequently co-administered in anecdotal healing protocols; no controlled interaction data(minor)
Which Should You Take?
N-Acetyl Cysteine comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC, oral dosing, with a Tier-A outcome catalogued. TB-500 is the right call when one of the conditionals below applies.
- → If your priority is healthspan extension, pick N-Acetyl Cysteine.
- → If your priority is liver function, pick N-Acetyl Cysteine.
- → If your priority is tendon repair, pick TB-500.
- → If your priority is wound healing, pick TB-500.
Edge case: If you want to avoid research-only / gray-market sourcing, N-Acetyl Cysteine is the more accessible choice.
Default choice: N-Acetyl Cysteine. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for TB-500 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 TB-500?
N-Acetyl Cysteine and TB-500 differ in category (supplement vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, N-Acetyl Cysteine or TB-500?
N-Acetyl Cysteine half-life is 5.6 hours; TB-500 half-life is 2 hours.
Can you stack N-Acetyl Cysteine with TB-500?
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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