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evidence · mechanism · dose
Supplements/Amino Acid

L-Ornithine

Urea-cycle amino acid that lowers fatigue and supports nighttime GH release.

Growth Hormone SupportEnergy ProductionSleep & Recovery

Overview

Urea-cycle amino acid that lowers fatigue and supports nighttime GH release.

Natural sources
    Common forms

      Mechanism of action

      Detoxifies ammonia via urea cycle; combined with arginine for GH synergy.

      Pathways

        Effects on the body

        Organ system effects

        Evidence-based benefits

        Reduces fatigue post-exercise

        Limited evidence

        Potential side effects

        Common
          Rare
            Serious

              Drug interactions

              No notable interactions reported.

              Safety & non-supplemental interactions

              Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.

              Avoid / monitor with these medications
              • ·Alcohol, benzodiazepines, opioids, sedating antihistamines (additive CNS depression)

              Supplement interactions

              Pairs well with

              None listed.

              Avoid combining with

              No specific avoidances listed.

              Dosing & bioavailability

              Typical dose
              2–6 g pre-bed
              With food?
              Empty stomach

              Where to buy

              Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

              Amino Acid
              L-Ornithine
              Amazon
              Wide selection · fast shipping
              Amino Acid
              L-Ornithine
              iHerb
              Global delivery · curated brands
              Amino Acid
              L-Ornithine
              Thorne
              Practitioner-grade · NSF tested

              Scientific evidence (8)

              RCTNutr Res · 2014

              Ornithine on fatigue and stress

              Miyake M, et al.

              8-week RCT of L-ornithine in subjects with fatigue.

              Key findings

              Reduced fatigue and improved sleep quality.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Ornithine — Reduces fatigue post-exercise

              Live PubMed search

              Live results for "L-Ornithine Reduces fatigue post-exercise" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Ornithine and "Reduces fatigue post-exercise". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Ornithine — randomized controlled trial

              Live PubMed search

              Live results for "L-Ornithine randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Ornithine and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Ornithine — meta-analysis

              Live PubMed search

              Live results for "L-Ornithine meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Ornithine and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Ornithine — pharmacokinetics

              Live PubMed search

              Live results for "L-Ornithine pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Ornithine and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Ornithine — safety adverse events

              Live PubMed search

              Live results for "L-Ornithine safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Ornithine and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Ornithine — dose response

              Live PubMed search

              Live results for "L-Ornithine dose response" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Ornithine and "dose response". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewGoogle Scholar · 1970

              Google Scholar: L-Ornithine — clinical evidence

              Live Scholar search

              Cross-database citation index for L-Ornithine as it relates to "clinical evidence".

              Key findings

              Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

              Open study
              Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.