Amino Acid
L-Cysteine HCl Anhydrous
Also known as: L-Cysteine Hydrochloride, N-Acetyl-L-Cysteine precursor, Cysteine HCl
L-Cysteine HCl is a semi-essential amino acid that serves as a precursor to glutathione, a major cellular antioxidant. It plays roles in protein synthesis, detoxification, and hair/skin/nail health.
Primary uses
- Glutathione production
- Antioxidant support
- Hair, skin, and nail health
- Detoxification support
- Immune function
How it works
- Precursor to glutathione synthesis
- Disulfide bond formation in proteins
- Cellular antioxidant defense
- Chelation of heavy metals
Dosage
- Typical range
- 500-1,500 mg daily
- Timing
- Any time; may divide doses
- With food
- Can take with or without food
- Duration
- Safe for long-term use; effects on antioxidant status build over weeks
- Special populations
- Individuals with homocystinuria should avoid or use under medical supervision
Forms
- Powder· 70/100
- HCl salt· 70/100
Safety
Common side effects
- Nausea
- Diarrhea
- Abdominal discomfort
- Headache (rare)
Contraindications
- Homocystinuria (genetic metabolic disorder)
- Cystinosis
- Pregnancy and lactation (limited safety data; use only if medically indicated)
Evidence notes
Good evidence for cysteine's role in glutathione synthesis and antioxidant support from mechanistic and clinical studies. RCT evidence exists for specific conditions (acetaminophen toxicity, respiratory health) though most general wellness uses are supported by moderate evidence.
Grade B: Some human trials support key claims; further confirmation needed.
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