Amino Acid
L-Ornithine Hydrochloride
Also known as: L-Ornithine HCl, Ornithine HCl, L-Ornithine, Ornithine
L-Ornithine is a non-essential amino acid involved in the urea cycle and polyamine synthesis, with some evidence suggesting potential benefits for athletic performance and muscle recovery. Research on ornithine supplementation is limited and mixed, with most studies examining small populations.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every L-Ornithine Hydrochloride product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Nutricost Pre-Workout For Women Powder | 89 A | $0.73 |
| 2 | Nutricost Pre-Workout Complex | 89 A | $0.83 |
| 3 | NOW Foods Tri-Amino | 81 A- | $0.27 |
| 4 | Pure Encapsulations Growth Hormone Support | 77 B+ | $0.88 |
| 5 | Nutricost L-Arginine L-Ornithine Capsules | 76 B+ | $0.11 |
| 6 | NOW Foods Arginine & Ornithine | 71 B | $0.21 |
| 7 | Nutricost L-Ornithine Capsules | 70 B | $0.09 |
| 8 | BulkSupplements L-Ornithine HCl Capsules | 69 B | $0.06 |
| 9 | Bluebonnet Nutrition L-ARGININE L-ORNITHINE 500 mg/250 mg | 68 B | $0.42 |
| 10 | Integrative Therapeutics Detoxication Factors | 64 B- | $1.17 |
| 11 | Bluebonnet Nutrition L-ORNITHINE 500 mg | 62 B- | $0.40 |
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-Ornithine Hydrochloride should I take?
The typical range is 2–5 grams daily. Typically studied in 4–8 week protocols; longer-term safety data limited
When should I take L-Ornithine Hydrochloride?
Between meals or pre-workout/post-workout. Can be taken with or without food; may be better tolerated with light food if GI sensitivity occurs.
Which form of L-Ornithine Hydrochloride is best?
Powder. Other forms in the catalog: Capsule, Hydrochloride salt.
Is L-Ornithine Hydrochloride safe?
Commonly reported: Gastrointestinal discomfort (nausea, diarrhea at higher doses), Headache (reported in some studies), Abdominal cramping.
Which L-Ornithine Hydrochloride supplement scores highest?
Nutricost Pre-Workout For Women Powder, at 89/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Primary uses
- Athletic performance and endurance
- Muscle recovery support
- Growth hormone support
- Immune function
How it works
- Substrate for urea cycle and nitrogen metabolism
- Precursor for polyamine synthesis
- Potential stimulator of growth hormone release
- Support for creatine and arginine metabolism
Dosage
- Typical range
- 2–5 grams daily
- Timing
- Between meals or pre-workout/post-workout
- With food
- Can be taken with or without food; may be better tolerated with light food if GI sensitivity occurs
- Duration
- Typically studied in 4–8 week protocols; longer-term safety data limited
- Special populations
- Pregnant/nursing women should consult a healthcare provider; individuals with kidney disease or on dialysis should avoid without medical supervision due to nitrogen metabolism
Forms
- Powder· 70/100
- Capsule· 70/100
- Hydrochloride salt· 70/100
Safety
Common side effects
- Gastrointestinal discomfort (nausea, diarrhea at higher doses)
- Headache (reported in some studies)
- Abdominal cramping
Contraindications
- Severe renal impairment or end-stage kidney disease
- Cirrhosis or advanced liver disease
- Arginine-restricted diets (ornithine can compete with arginine metabolism)
Products containing L-Ornithine Hydrochloride
Top-scoring supplements in our catalog that list L-Ornithine Hydrochloride on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Limited clinical research with mostly small trials. Some studies suggest benefits for ammonia clearance and endurance performance, but evidence is preliminary and inconsistent. Not established as a primary performance supplement.
Grade C: Mostly observational or small trials; mechanism is plausible but unproven at scale.
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.