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.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every L-Cysteine HCl Anhydrous product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Bluebonnet Nutrition L-CYSTEINE 500 mg | 81 A- | $0.42 |
| 2 | Integrative Therapeutics Glutathione Cell Defense | 73 B+ | $2.01 |
| 3 | Bluebonnet Nutrition ULTIMATE HAIR & NAIL FORMULA | 69 B | $1.35 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much L-Cysteine HCl Anhydrous should I take?
The typical range is 500-1,500 mg daily. Safe for long-term use; effects on antioxidant status build over weeks
When should I take L-Cysteine HCl Anhydrous?
Any time; may divide doses. Can take with or without food.
Which form of L-Cysteine HCl Anhydrous is best?
Powder. Other forms in the catalog: HCl salt.
Is L-Cysteine HCl Anhydrous safe?
Commonly reported: Nausea, Diarrhea, Abdominal discomfort, Headache (rare).
Which L-Cysteine HCl Anhydrous supplement scores highest?
Bluebonnet Nutrition L-CYSTEINE 500 mg, at 81/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
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)
Products containing L-Cysteine HCl Anhydrous
Top-scoring supplements in our catalog that list L-Cysteine HCl Anhydrous on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
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.
Related in Amino Acid
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.