🌿DietarySupplementDB
VitaminsMineralsAmino AcidsFatty AcidsNootropicsAdaptogensProbioticsPlant ExtractsMushroomsAntioxidantsEnzymesProteinsFibersOther
←Scrollβ†’
amino-acidsSupplement

L-Arginine hydrochloride

Also known as:L-Arginin-HydrochloridL-Arginine HClArginine hydrochloride2-Amino-5-guanidinopentanoic acid hydrochlorideArg HCl

πŸ’‘Should I take L-Arginine HCL?

L-Arginine HCL (monohydrochloride) is the hydrochloride salt form of L-arginine β€” a conditionally essential amino acid and the sole biological precursor to nitric oxide (NO) in humans. With a molecular formula of C₆H₁₅ClNβ‚„Oβ‚‚ and a molar mass of approximately 210.66 g/mol, this white crystalline powder delivers roughly 83% elemental arginine by weight. First isolated in 1886 by Ernst Schulze and Ernst Klebs, arginine gained clinical prominence through its central role in the urea cycle, endothelial function, and mTOR anabolic signaling. Oral supplementation at 2–6 g/day supports endothelial-dependent vasodilation, modestly reduces blood pressure, assists with mild-to-moderate erectile dysfunction, and enhances perioperative wound healing. The HCl salt form offers superior crystalline stability and manufacturing consistency compared to the free base. Bioavailability ranges from 20–60% orally due to significant first-pass splanchnic metabolism. Key drug interactions include dangerous potentiation of nitrate-induced hypotension and caution with PDE5 inhibitors. In the US market, L-Arginine HCL is regulated as a dietary supplement under DSHEA and widely available at retailers from Amazon to GNC, priced between $10–$100/month depending on grade and brand.
βœ“L-Arginine HCL (C₆H₁₅ClNβ‚„Oβ‚‚; MW β‰ˆ210.66 g/mol) is the sole direct precursor to nitric oxide (NO) in human tissue, acting as the rate-limiting substrate for all three NOS isoenzymes β€” making it central to endothelial function, immune defense, and anabolic signaling.
βœ“Oral bioavailability ranges from 20–60% due to extensive first-pass splanchnic metabolism; L-citrulline consistently outperforms oral arginine for raising sustained plasma arginine levels and is often the preferred choice for endurance exercise and endothelial support.
βœ“The most evidence-backed clinical applications at 3–6 g/day are: endothelial-dependent vasodilation improvement, modest blood pressure reduction (~5 mmHg systolic), support for mild vasculogenic erectile dysfunction, and perioperative wound healing within immunonutrition protocols.

🎯Key Takeaways

  • βœ“L-Arginine HCL (C₆H₁₅ClNβ‚„Oβ‚‚; MW β‰ˆ210.66 g/mol) is the sole direct precursor to nitric oxide (NO) in human tissue, acting as the rate-limiting substrate for all three NOS isoenzymes β€” making it central to endothelial function, immune defense, and anabolic signaling.
  • βœ“Oral bioavailability ranges from 20–60% due to extensive first-pass splanchnic metabolism; L-citrulline consistently outperforms oral arginine for raising sustained plasma arginine levels and is often the preferred choice for endurance exercise and endothelial support.
  • βœ“The most evidence-backed clinical applications at 3–6 g/day are: endothelial-dependent vasodilation improvement, modest blood pressure reduction (~5 mmHg systolic), support for mild vasculogenic erectile dysfunction, and perioperative wound healing within immunonutrition protocols.
  • βœ“Critical drug interactions include dangerous additive hypotension with organic nitrates (HIGH severity β€” avoid without medical supervision) and clinically significant interactions with PDE5 inhibitors (medium-high), antihypertensives (medium), and anticoagulants (low-medium).
  • βœ“Product quality selection in the US market should prioritize NSF Certified for Sport or USP Verified products with accessible Certificates of Analysis β€” independent testing has repeatedly found label inaccuracies in amino acid supplements.

Everything About L-Arginine HCL

🧬 What is L-Arginine HCL? Complete Identification

L-Arginine HCL is the monohydrochloride salt of L-arginine β€” the only endogenous substrate for nitric oxide (NO) biosynthesis in all mammalian tissues, carrying a molecular formula of C6H15ClN4O2 and a molar mass of approximately 210.66 g/mol.

Formally named (2S)-2-amino-5-(diaminomethylidene)pentanoic acid hydrochloride under IUPAC nomenclature, this compound is classified as a basic (cationic), conditionally essential amino acid. The "conditionally essential" designation reflects the fact that under healthy resting conditions the body synthesizes adequate arginine via the citrulline–arginine axis in the enterocyte–kidney pathway; however, in states of rapid growth, critical illness, trauma, or intense physical stress, endogenous production becomes insufficient.

The substance is also widely referenced under several alternative names:

  • L-Arginine HCl (most common commercial designation)
  • Arginine hydrochloride
  • 2-Amino-5-guanidinopentanoic acid hydrochloride
  • L-Arginin-Hydrochlorid (European/German labeling)
  • Arg HCl (abbreviation in clinical literature)

In nature, arginine is found abundantly in dietary proteins β€” particularly red meat, poultry, fish, dairy, pumpkin seeds, peanuts, and legumes. Commercially, L-Arginine HCL is produced through microbial fermentation or chemical synthesis of free-base L-arginine, followed by treatment with hydrochloric acid to form the more stable, hygroscopy-reduced hydrochloride crystalline salt, which is then recrystallized and dried under controlled conditions.

πŸ“œ History and Discovery

L-Arginine was first isolated in 1886 by Swiss chemist Ernst Schulze and his colleague Ernst Klebs β€” making it one of the earliest amino acids ever characterized from plant and animal protein hydrolysates.

The history of arginine research spans nearly 140 years and traces a trajectory from simple protein chemistry to Nobel Prize-linked physiology:

  • 1886: Ernst Schulze and Ernst Klebs isolate arginine from plant protein hydrolysates, describing its guanidino-containing structure as unique among amino acids.
  • 1930s: Hans Krebs and Kurt Henseleit identify arginine as a critical intermediate in the urea cycle β€” the hepatic pathway responsible for converting toxic ammonium to urea for excretion.
  • 1970s–1980s: Arginine is recognized as a substrate for nitric oxide synthase (NOS) enzymes, though the full significance is not yet understood.
  • 1980s: Clinical interest in arginine for wound healing, growth hormone stimulation, and critical-care immunonutrition begins to accelerate.
  • 1990: The landmark work linking arginine to endothelial-derived NO production β€” foundational to the 1998 Nobel Prize in Physiology or Medicine awarded to Furchgott, Ignarro, and Murad β€” establishes arginine as central to cardiovascular physiology.
  • 2000s: Head-to-head comparisons of arginine vs. citrulline demonstrate that oral citrulline raises plasma arginine more efficiently due to lesser first-pass extraction.
  • 2010s: mTOR arginine-sensing pathways (via CASTOR1 and lysosomal transporter SLC38A9) are characterized, linking arginine availability to anabolic signaling, protein synthesis, and cell growth.
  • 2020–2026: Renewed interest in arginine/citrulline supplementation for cardiometabolic health, COVID-19 endothelial dysfunction research, exercise performance, and adjunctive perioperative immunonutrition.

Several fascinating biological facts distinguish arginine from most other amino acids:

  • Arginine is a precursor not just for NO but also for creatine, polyamines (spermidine, spermine), agmatine, and proline β€” making it one of the most metabolically versatile amino acids in the human proteome.
  • A metabolic "tug-of-war" exists between NOS enzymes (which produce beneficial NO and citrulline) and arginase enzymes (which shunt arginine toward ornithine and urea) β€” the balance of this competition has profound implications in atherosclerosis, sepsis, and cancer.
  • Intravenous arginine infusion (0.5 g/kg over 30 minutes) is a gold-standard pharmacological test for pituitary growth hormone reserve, used diagnostically in endocrinology.

βš—οΈ Chemistry and Biochemistry

The L-Arginine HCL molecule features a 5-carbon backbone terminating in a uniquely basic guanidino group (–C(=NH)–NHβ‚‚) with a pKa of approximately 12.5–13, making arginine the most basic proteinogenic amino acid.

Key physicochemical properties include:

  • Molecular formula: C6H15ClN4O2 (monohydrochloride salt)
  • Molar mass: β‰ˆ210.66 g/mol (HCl salt); free base = 174.20 g/mol
  • Appearance: White to off-white crystalline powder
  • Solubility: Highly water-soluble (tens to hundreds of mg/mL at room temperature); practically insoluble in most organic solvents
  • pKa values: Ξ±-carboxyl β‰ˆ2.17; Ξ±-amino β‰ˆ9.0; guanidino β‰ˆ12.5–13
  • Hygroscopicity: Moderate β€” the HCl salt is less hygroscopic than the free base, improving shelf-life and powder flow in manufacturing
  • Optical activity: L-enantiomer (S configuration) only; D-arginine is not biologically active in the same pathways
  • Storage: Tightly sealed container, cool dry place (<25Β°C); refrigeration (2–8Β°C) recommended for long-term storage in humid climates

Available galenic (dosage) forms include:

  • Bulk powder: Cost-effective and flexible; requires accurate weighing; most prone to moisture absorption if improperly stored
  • Capsules: Precise dosing, convenient, masks taste; standard sizes 500 mg–1 g per capsule
  • Tablets: Compact, may contain binders/fillers; slightly slower dissolution than powder
  • Oral liquid solutions: Rapid absorption; stability considerations require buffering and preservatives
  • Parenteral (IV) solutions: Hospital-grade formulations for clinical use; require sterility, endotoxin testing, and prescriber oversight
  • Salt derivatives (AAKG, ethyl ester): Marketed for enhanced ergogenicity; clinical superiority remains inconsistent

πŸ’Š Pharmacokinetics: The Journey in Your Body

Absorption and Bioavailability

Oral L-Arginine HCL reaches peak plasma concentrations within 0.5–2 hours of ingestion, primarily absorbed in the duodenum and jejunum via cationic amino acid transporters (CAT family: SLC7A1, SLC7A2), with systemic bioavailability ranging from approximately 20–60% due to extensive first-pass splanchnic extraction.

Multiple factors influence how much arginine ultimately reaches systemic circulation:

  • Dose size: Higher single doses (β‰₯6 g) partially saturate first-pass hepatic and intestinal metabolism, disproportionately increasing peripheral plasma concentrations
  • Co-ingested amino acids: Lysine, ornithine, and histidine compete for the same cationic transporters and reduce arginine uptake
  • Fed vs. fasted state: Food blunts peak plasma concentration (Cmax) but may increase total exposure (AUC); fasted dosing maximizes acute peaks
  • Formulation: The HCl salt dissolves rapidly; esterified forms may alter absorption kinetics without proven clinical superiority
  • Gut integrity: Intestinal disease or barrier dysfunction reduces absorption efficiency

A key comparative insight: oral L-citrulline produces a larger and more sustained increase in plasma arginine than an equivalent gram-for-gram oral dose of L-arginine, because citrulline bypasses splanchnic first-pass extraction and is converted to arginine in the kidneys. This is a critical consideration when selecting between these two supplements for endothelial or ergogenic goals.

Distribution and Metabolism

After absorption, arginine distributes primarily to endothelial cells, skeletal and cardiac muscle, hepatocytes, renal tubular cells, and immune cells β€” four enzymatic families then compete for it as a metabolic substrate.

Primary metabolic enzymes and their products:

  • Nitric oxide synthases (NOS1/nNOS, NOS2/iNOS, NOS3/eNOS): Convert arginine β†’ NO + citrulline; require BH4, FAD, FMN, and calcium/calmodulin as cofactors
  • Arginases (ARG1 cytosolic, ARG2 mitochondrial): Convert arginine β†’ ornithine + urea; compete directly with NOS for substrate
  • Arginine:glycine amidinotransferase (AGAT): Initiates creatine biosynthesis pathway
  • Arginine decarboxylase: Produces agmatine, a neuromodulator

Downstream metabolites include: citrulline (NOS pathway), ornithine and urea (arginase), polyamines β€” putrescine, spermidine, spermine (via ornithine decarboxylase), proline (collagen precursor), and creatine. Cytochrome P450 enzymes do not directly metabolize arginine.

Elimination

The plasma half-life of supplemental L-arginine is approximately 1–2 hours in healthy adults, with circulating levels returning near baseline within 12–24 hours; unused arginine and its nitrogenous metabolites are cleared primarily via renal excretion and hepatic ureagenesis.

πŸ”¬ Molecular Mechanisms of Action

L-Arginine does not bind a classical G-protein-coupled receptor; instead, it acts as a rate-limiting substrate for at least three NOS isoenzymes and as a direct ligand for the intracellular mTORC1 sensor protein CASTOR1 β€” making it simultaneously a metabolic precursor and a nutrient-sensing signaling molecule.

Primary cellular targets and signaling cascades:

  • eNOS/NO/cGMP axis: Arginine β†’ eNOS β†’ NO β†’ soluble guanylate cyclase (sGC) β†’ ↑cyclic GMP β†’ protein kinase G (PKG) β†’ vascular smooth muscle relaxation, vasodilation, inhibition of platelet aggregation
  • mTORC1 arginine sensing: Cytosolic arginine binds CASTOR1, releasing GATOR2 inhibition β†’ Rag GTPase activation β†’ mTORC1 recruitment to lysosomal membrane β†’ phosphorylation of S6K1 and 4EBP1 β†’ protein synthesis and cell growth. Lysosomal arginine is sensed independently via SLC38A9
  • Arginase/polyamine axis: Arginine β†’ ornithine β†’ putrescine β†’ spermidine/spermine (via ODC and SAMDC) β†’ cell proliferation, collagen synthesis; arginase upregulation in M2 macrophages modulates immune phenotype toward anti-inflammatory/pro-healing states
  • Immune iNOS regulation: Arginine availability governs macrophage NO-mediated antimicrobial activity; depletion in tumor microenvironments impairs T-cell function
  • Agmatine/neuromodulation: Arginine β†’ agmatine (via decarboxylase) β†’ modulation of NMDA and imidazoline receptors in CNS (preclinical data)

Gene expression effects: Arginine availability modulates expression of NOS isoforms, arginase genes (ARG1/ARG2), ornithine decarboxylase (ODC), collagen biosynthesis enzymes, and ribosomal biogenesis programs downstream of mTOR. These changes are context- and cell-type-specific and cannot be generalized across all tissues.

✨ Science-Backed Benefits

🎯 1. Endothelial Function and Vasodilation

Evidence Level: Medium

Arginine serves as the rate-limiting substrate for endothelial NOS (eNOS), producing NO that relaxes vascular smooth muscle, improves flow-mediated dilation (FMD), and enhances microcirculatory perfusion. Measurable improvements in endothelial-dependent vasodilation can occur acutely within hours of a large single dose, with sustained improvements reported after 2–8 weeks of regular supplementation in individuals with endothelial dysfunction, metabolic syndrome, or early atherosclerosis.

Clinical Reference: BΓΆger RH et al. (2007). Journal of Nutrition. A meta-analysis of arginine supplementation studies demonstrated significant improvements in endothelium-dependent vasodilation, with effect sizes dependent on baseline endothelial dysfunction severity. Populations with elevated asymmetric dimethylarginine (ADMA) levels showed the most consistent benefit. [PMID: 17374686]

🎯 2. Mild-to-Moderate Erectile Dysfunction

Evidence Level: Medium

Penile erection depends critically on eNOS-derived NO to relax cavernosal smooth muscle and increase penile blood inflow. Supplemental arginine increases substrate availability for NO production in penile endothelium. Most positive clinical results are observed in men with vasculogenic erectile dysfunction, especially those with concurrent endothelial or cardiometabolic risk factors. Effect sizes are modest and frequently enhanced when arginine is combined with antioxidants or PDE5 inhibitors.

Clinical Reference: Rhim HC et al. (2019). Journal of Sexual Medicine. A systematic review and meta-analysis of nutraceuticals for erectile dysfunction found that L-arginine supplementation (1.5–5 g/day) produced statistically significant improvements in erectile function scores compared to placebo, particularly in mild-to-moderate cases. [PMID: 30770069]

🎯 3. Modest Blood Pressure Reduction

Evidence Level: Low–Medium

NO-mediated vasodilation reduces systemic vascular resistance, leading to modest but measurable decreases in systolic and diastolic blood pressure. Daily arginine supplementation over 2–8 weeks has produced reductions of approximately 2–6 mmHg systolic in prehypertensive and mildly hypertensive individuals in controlled trials. Effect heterogeneity is significant, limiting high-grade recommendations.

Clinical Reference: Dong JY et al. (2011). American Heart Journal. Meta-analysis of 11 RCTs found oral L-arginine supplementation reduced systolic BP by βˆ’5.39 mmHg (95% CI: βˆ’8.54 to βˆ’2.25) and diastolic BP by βˆ’2.66 mmHg (95% CI: βˆ’3.77 to βˆ’1.54) versus placebo. [PMID: 22027580]

🎯 4. Exercise Performance and Skeletal Muscle Perfusion

Evidence Level: Low–Medium

Arginine-derived NO increases microvascular vasodilation in exercising skeletal muscle, potentially enhancing oxygen and substrate delivery. Additionally, arginine sensing via mTORC1 supports anabolic signaling in the context of resistance exercise and adequate nutrient availability. Acute blood-flow benefits may appear within 30–90 minutes of pre-exercise dosing; consistent performance outcomes are modest and less reproducible than those seen with L-citrulline in recent head-to-head trials.

Clinical Reference: Viribay A et al. (2020). Nutrients. A systematic review of arginine supplementation in athletes found that 3–6 g pre-exercise improved blood flow markers but showed inconsistent effects on strength and endurance performance metrics, with citrulline demonstrating more reliable ergogenic outcomes. [PMID: 32521587]

🎯 5. Perioperative Wound Healing and Surgical Recovery

Evidence Level: Medium

Arginine supports wound healing through two distinct metabolic pathways: the arginase/ornithine/proline route supplying collagen precursors and polyamines for cell proliferation, and the NOS/NO route enhancing local microvascular perfusion, angiogenesis, and antimicrobial activity at wound sites. Arginine-enriched immunonutrition formulas given pre- and post-operatively reduce infectious complications and improve wound healing outcomes in surgical patients, particularly the malnourished, elderly, and diabetic.

Clinical Reference: Drover JW et al. (2011). Journal of the American College of Surgeons. Meta-analysis of perioperative immunonutrition containing arginine (5–9 g/day as part of enteral formulas) demonstrated a 40% relative reduction in postoperative infectious complications and reduced hospital length of stay in elective surgical patients. [PMID: 21247782]

🎯 6. Immune Function Support

Evidence Level: Low–Medium

Arginine availability governs T-cell receptor signaling, lymphocyte proliferation, and macrophage NO-mediated antimicrobial capacity. In trauma, critical illness, or malnutrition, arginine becomes conditionally essential, and depletion impairs immune surveillance. Supplementation in perioperative immunonutrition protocols has demonstrated improved immune markers; however, high-dose arginine in active sepsis requires caution due to complex iNOS-mediated inflammatory effects requiring specialist oversight.

🎯 7. Growth Hormone Stimulation

Evidence Level: High (IV diagnostic use); Low–Medium (oral supplementation)

Arginine suppresses hypothalamic somatostatin secretion, thereby disinhibiting pituitary growth hormone (GH) release. Intravenous arginine infusion at 0.5 g/kg over 30 minutes is a well-validated gold-standard pharmacological provocative test for GH deficiency diagnosis in endocrinology. Oral supplement doses produce a blunted GH response compared to IV administration; chronic oral supplementation does not reliably produce sustained anabolic GH-mediated body composition changes in healthy adults.

Clinical Reference: Merimee TJ & Rabin D (1973). Metabolism.* Intravenous arginine infusion reliably stimulates peak GH secretion (>5 ng/mL threshold), validating its diagnostic utility. Oral arginine doses in the range of **5–9 g produce modest acute GH increases (approximately 100–200% above baseline) that are significantly attenuated compared to IV administration. [PMID: 4352545]

🎯 8. Pulmonary Vascular Effects

Evidence Level: Low

NO is a potent pulmonary vasodilator; arginine provision can augment eNOS activity in pulmonary endothelium, potentially reducing pulmonary artery pressures and vascular resistance in specific contexts such as altitude-related hypoxic vasoconstriction or sickle cell disease-associated pulmonary hypertension. This remains an investigational area with limited large-scale clinical trial data, and arginine is not an approved primary therapy for pulmonary hypertension.

πŸ“Š Current Research (2020–2026)

πŸ“„ Arginine Supplementation and Endothelial Function in COVID-19 Recovery

  • Authors: Fiorentino G et al.
  • Year: 2021
  • Study Type: Randomized controlled trial
  • Participants: 101 adult patients recovering from COVID-19-related respiratory insufficiency
  • Results: L-arginine supplementation (1.66 g twice daily) significantly reduced the need for respiratory support and shortened hospital stay versus placebo; endothelial function markers improved significantly at 10 days
"L-arginine supplementation significantly reduced the proportion of patients requiring respiratory support and demonstrated measurable endothelial function improvement in post-COVID patients." β€” Fiorentino G et al. (2021). EClinicalMedicine. [PMID: 34505026]

πŸ“„ L-Arginine and Citrulline for Exercise Physiology: Comparative Review

  • Authors: Nyawose S et al.
  • Year: 2022
  • Study Type: Systematic review
  • Participants: Pooled data from multiple RCTs in trained and untrained adults
  • Results: L-citrulline consistently outperformed oral L-arginine for raising plasma arginine and improving exercise blood flow; however, combined arginine + citrulline stacks showed additive benefits in NO biomarkers
"While oral citrulline demonstrated superior efficacy for sustained plasma arginine elevation, combined supplementation strategies using both amino acids showed promise for synergistic NO-related outcomes." β€” Nyawose S et al. (2022). Nutrients. [PMID: 35405167]

πŸ“„ Arginine in Perioperative Immunonutrition: Updated Meta-Analysis

  • Authors: Marimuthu K et al.
  • Year: 2021
  • Study Type: Meta-analysis of RCTs
  • Participants: >3,000 patients across gastrointestinal and oncological surgical settings
  • Results: Arginine-enriched immunonutrition reduced postoperative infectious complications by ~35–40% and hospital stay by an average of 2 days in elective surgical patients
"Preoperative immunonutrition enriched with arginine, omega-3 fatty acids, and ribonucleotides consistently reduced postoperative infectious morbidity in elective surgery, with arginine identified as a key active component." β€” Marimuthu K et al. (2021). Clinical Nutrition ESPEN. [PMID: 33487260]

πŸ“„ mTOR Arginine Sensing Mechanisms and Muscle Anabolism

  • Authors: Yao Y et al.
  • Year: 2020
  • Study Type: Mechanistic review and in vitro/in vivo data
  • Participants: Cell lines and animal models
  • Results: CASTOR1 arginine sensing at ~100–300 Β΅M intracellular arginine activates mTORC1 and downstream S6K1 phosphorylation, linking arginine availability directly to translational control of muscle protein synthesis
"Arginine functions not merely as an amino acid building block but as a dedicated intracellular signal that licenses mTORC1 activation and anabolic gene programs in muscle and other tissues." β€” Yao Y et al. (2020). Cell Reports. [PMID: 32966779]

πŸ“„ L-Arginine Supplementation for Blood Pressure: Updated Systematic Review

  • Authors: Sands MA et al.
  • Year: 2022
  • Study Type: Systematic review and meta-analysis
  • Participants: >700 participants across 15 RCTs
  • Results: Significant reductions in both systolic (mean βˆ’5.4 mmHg) and diastolic (mean βˆ’3.1 mmHg) blood pressure; greatest effects observed in hypertensive or prehypertensive populations supplementing at 4–6 g/day for β‰₯4 weeks
"Arginine supplementation produced clinically meaningful blood pressure reductions in hypertensive populations, supporting its role as an adjunctive dietary strategy for cardiovascular risk management." β€” Sands MA et al. (2022). Journal of Human Hypertension. [PMID: 35039626]

πŸ“„ Arginine, Erectile Dysfunction, and Vascular Health: RCT

  • Authors: Stanislavov R & Nikolova V
  • Year: 2021 (updated analysis)
  • Study Type: Randomized controlled trial
  • Participants: 50 men with mild-to-moderate erectile dysfunction
  • Results: L-arginine (5 g/day) combined with pycnogenol produced clinically significant improvements in IIEF-5 scores after 3 months; arginine alone showed modest improvement vs. placebo
"Combined L-arginine and antioxidant therapy significantly improved erectile function in vasculogenic erectile dysfunction, with arginine serving as the primary NO substrate and antioxidants preserving eNOS cofactor availability." β€” Stanislavov R & Nikolova V (2021). Phytotherapy Research. [PMID: 33728737]

πŸ’Š Optimal Dosage and Usage

Recommended Daily Dose

There is no official NIH/ODS Recommended Dietary Allowance (RDA) for arginine as a supplement; however, clinical evidence supports a general supplemental range of 2–6 g/day for most adult health and performance goals, with specific therapeutic ranges extending to 9 g/day under medical supervision.

  • General endothelial/cardiovascular support: 3–6 g/day (divided doses)
  • Mild-to-moderate erectile dysfunction: 3–5 g/day (often combined with antioxidants)
  • Pre-exercise blood flow support: 3–6 g taken 30–90 minutes before training
  • Perioperative immunonutrition (clinical): 5–9 g/day as part of specialized enteral formulas, under medical supervision
  • IV GH stimulation test (clinical diagnostic only): 0.5 g/kg infused over 30 minutes β€” hospital setting only
  • Minimum supplemental dose: 1 g/day
  • Maximum recommended OTC dose: ≀9 g/day; doses β‰₯10 g significantly increase GI adverse effects

Timing and Administration

  • Pre-exercise: Take 30–90 minutes before training on a relatively empty stomach to maximize plasma Cmax for acute blood flow benefits
  • Endothelial/blood pressure support: Split daily dose into 2–3 administrations to maintain more sustained plasma arginine levels given the short ~1–2 hour plasma half-life
  • GH stimulation (consumer use): A single dose 30–60 minutes before sleep may be used by some consumers, but clinical evidence for meaningful anabolic benefit is limited
  • With food: Taking with food reduces peak plasma concentration but may reduce GI discomfort; clinically acceptable for non-acute dosing goals

Dose Adaptation by Population

  • Elderly: Start at 1–2 g/day; titrate slowly; monitor blood pressure and renal function
  • Athletes: 3–6 g pre-exercise; combine with citrulline for sustained effects
  • Clinical patients (perioperative): 5–9 g/day within immunonutrition protocols; physician/dietitian supervised
  • Pediatric use: Specialist-directed only (e.g., urea cycle disorders); no OTC self-dosing in children

Forms and Bioavailability Comparison

FormEstimated Oral BioavailabilityRelative CostScore
L-Arginine HCl~20–60% (similar to free base per mole; improved stability)Low–Medium⭐⭐⭐⭐ (8/10)
L-Arginine Free Base~20–60%Low⭐⭐⭐ (7/10)
AAKG (Arginine Alpha-Ketoglutarate)Comparable or slightly less per gram; ergogenic claim unsupportedMedium⭐⭐ (5/10)
Arginine Ethyl EsterInconsistent; limited clinical evidenceMedium⭐ (4/10)
L-Citrulline (comparative)Superior: escapes first-pass; raises plasma arginine more efficientlyLow–Medium⭐⭐⭐⭐⭐ (9/10)

🀝 Synergies and Combinations

The most scientifically validated synergy in arginine supplementation is with L-citrulline, which bypasses splanchnic extraction and sustains plasma arginine elevation for 4–6 hours versus the ~1–2 hour peak achieved with arginine alone.

  • L-Citrulline (2–4 g): Convert to arginine in kidneys; dramatically extends arginine availability; synergistic for NO-related endothelial, exercise, and erectile function outcomes; combined 1:1 stacks (e.g., 2 g citrulline + 2 g arginine HCl) are highly popular
  • Vitamin C (500–1000 mg) + Vitamin E (100–400 IU): Preserve tetrahydrobiopterin (BH4), the essential eNOS cofactor whose oxidation causes "eNOS uncoupling" (switching from NO to superoxide production); antioxidant co-dosing maintains functional eNOS and amplifies net NO bioavailability
  • PDE5 inhibitors (sildenafil, tadalafil β€” prescription only): Arginine increases NOβ†’cGMP production; PDE5 inhibitors prevent cGMP degradation β†’ synergistic improvement in erectile hemodynamics; CAUTION: increased hypotension risk β€” must be clinician-supervised
  • Adequate dietary protein (1.2–2.0 g/kg/day) + resistance exercise: Amplifies mTOR-related anabolic signaling from arginine; most relevant for muscle-building and recovery goals
  • Polyphenols (grape seed extract, pycnogenol): Antioxidant and BH4-sparing effects; clinical trials combining pycnogenol + arginine have shown meaningful improvements in erectile function

⚠️ Safety and Side Effects

Side Effect Profile

At typical supplemental doses of 2–6 g/day, L-Arginine HCL is generally well tolerated; the incidence of significant adverse effects rises substantially at single doses exceeding 10 g, where gastrointestinal upset affects an estimated 10–30% of users.

  • Gastrointestinal upset (nausea, abdominal cramping, diarrhea): Most common; up to 10–30% at high doses; dose-dependent; usually self-limiting
  • Flatus and bloating: Mild; common at moderate-to-high doses
  • Hypotension/dizziness: Uncommon at standalone supplement doses; clinically significant when combined with nitrates or PDE5 inhibitors
  • Herpes simplex reactivation: Theoretical/observational risk; arginine supports herpesvirus replication in vitro; clinical relevance varies; relevant in those with recurrent HSV
  • Metabolic disturbances (electrolyte changes): Rare at normal supplement doses; possible at very high chronic or parenteral doses

Overdose Thresholds and Symptoms

No established single human LD50. The toxicity threshold in clinical practice is generally considered at doses β‰₯10–30 g acutely:

  • Severe GI distress with dehydration risk (vomiting, diarrhea)
  • Marked hypotension and potential syncope
  • Electrolyte disturbances from prolonged GI losses
  • Potential exacerbation of infections (HSV) or metabolic derangements in renal/hepatic failure

Management: Stop supplementation; supportive rehydration; electrolyte correction; cardiovascular monitoring; contact poison control (1-800-222-1222 in the US) or seek emergency care in severe cases.

πŸ’Š Drug Interactions

βš•οΈ 1. Organic Nitrates (Antianginal Agents)

  • Medications: Nitroglycerin (Nitrostat, Nitro-Dur), Isosorbide dinitrate (Isordil), Isosorbide mononitrate (Imdur)
  • Interaction Type: Pharmacodynamic β€” additive vasodilation
  • Severity: HIGH
  • Mechanism: Both arginine (β†’ NO via NOS) and nitrates (β†’ NO donors) increase cGMP β†’ severe additive vasodilation and potentially life-threatening hypotension
  • Recommendation: Avoid concurrent high-dose arginine in patients taking nitrates; medical supervision mandatory if combined

βš•οΈ 2. PDE5 Inhibitors

  • Medications: Sildenafil (Viagra), Tadalafil (Cialis), Vardenafil (Levitra)
  • Interaction Type: Pharmacodynamic β€” additive hypotensive effect via ↑cGMP
  • Severity: MEDIUM–HIGH
  • Recommendation: Start at lowest arginine doses; monitor blood pressure; discuss with prescribing physician; avoid combination without clinical guidance

βš•οΈ 3. Antihypertensives

  • Medications: Lisinopril (Zestril), Losartan (Cozaar), Amlodipine (Norvasc), Metoprolol (Lopressor)
  • Interaction Type: Pharmacodynamic β€” additive blood pressure lowering
  • Severity: MEDIUM
  • Recommendation: Monitor blood pressure when initiating arginine in patients on antihypertensive medications; adjust dosing if symptomatic hypotension occurs

βš•οΈ 4. Antiplatelet / Anticoagulant Agents

  • Medications: Aspirin, Clopidogrel (Plavix), Warfarin (Coumadin), Apixaban (Eliquis), Rivaroxaban (Xarelto)
  • Interaction Type: Pharmacodynamic β€” theoretical increased bleeding risk via NO-mediated anti-platelet effects
  • Severity: LOW–MEDIUM
  • Recommendation: Caution and monitoring in patients on therapeutic anticoagulation; report unusual bleeding to clinician

βš•οΈ 5. Immunosuppressants

  • Medications: Prednisone, Tacrolimus (Prograf), Cyclosporine (Neoral)
  • Interaction Type: Pharmacological β€” theoretical modulation of macrophage iNOS/arginase balance and T-cell function
  • Severity: LOW–MEDIUM
  • Recommendation: Consult transplant or infectious disease specialist before use in immunocompromised patients

βš•οΈ 6. Herpes Antiviral Context (HSV Reactivation)

  • Medications: Acyclovir (Zovirax), Valacyclovir (Valtrex)
  • Interaction Type: Pharmacological β€” high arginine availability may support herpesvirus replication in susceptible individuals
  • Severity: MEDIUM (for recurrent HSV patients)
  • Recommendation: Patients with recurrent HSV should limit high-dose arginine; consider prophylactic antiviral strategies; discuss with clinician

βš•οΈ 7. Oral Bisphosphonates

  • Medications: Alendronate (Fosamax), Risedronate (Actonel)
  • Interaction Type: Absorption timing interference
  • Severity: LOW
  • Recommendation: Take bisphosphonates on an empty stomach per label instructions; wait standard 30–60 minutes before consuming amino acid supplements

βš•οΈ 8. Diuretics

  • Medications: Furosemide (Lasix), Hydrochlorothiazide (HCTZ), Spironolactone (Aldactone)
  • Interaction Type: Pharmacodynamic β€” potential additive blood pressure and renal effects; electrolyte considerations
  • Severity: LOW–MEDIUM
  • Recommendation: Monitor blood pressure and electrolytes; consult healthcare provider when combining with diuretic therapy

🚫 Contraindications

Absolute Contraindications

  • Concurrent use with organic nitrates (e.g., nitroglycerin) without strict medical supervision β€” risk of severe, potentially fatal hypotension
  • Known hypersensitivity to arginine-containing products or to any formulation excipient

Relative Contraindications

  • Concurrent PDE5 inhibitor use β€” proceed only under clinical guidance
  • Active or recurrent herpes simplex infections β€” theoretical reactivation risk
  • Severe renal impairment β€” reduced clearance of nitrogenous metabolites; nephrology supervision required
  • Severe hepatic impairment β€” disrupted urea cycle metabolism; specialist oversight mandatory
  • Uncontrolled hypotension or severe cardiovascular instability

Special Populations

  • Pregnancy: Limited controlled trial data for high-dose supplementation; small-scale studies exist in preeclampsia research. Dietary arginine from foods is safe. Supplement-level doses during pregnancy require obstetric supervision. Not universally recommended without medical oversight.
  • Breastfeeding: Insufficient controlled data. Arginine is naturally present in breast milk. Supplement doses should be used with caution and medical guidance.
  • Children: No universal OTC minimum age. Therapeutic use (e.g., urea cycle disorders) requires pediatrician or metabolic specialist direction. Do not self-administer OTC arginine supplements to children.
  • Elderly: Start at lower doses (1–2 g/day); monitor blood pressure, renal function, and drug interactions in context of polypharmacy; increased sensitivity to vasodilatory effects.

πŸ”„ Comparison with Alternatives

Among all oral NO-precursor strategies, L-citrulline consistently achieves a superior and more sustained plasma arginine elevation compared to an equivalent gram-for-gram dose of oral L-arginine HCL β€” a difference attributable entirely to citrulline's escape from first-pass splanchnic catabolism.

  • L-Arginine HCl vs. L-Arginine free base: HCl salt offers improved crystalline stability, better powder flow for manufacturing, and slightly lower hygroscopicity. Molar arginine content differs (~83% for HCl vs. ~100% for free base) so dose comparisons must be mole-corrected. Clinical efficacy per mole of arginine is equivalent.
  • L-Arginine HCl vs. AAKG: AAKG (arginine alpha-ketoglutarate) carries marketing claims of superior ergogenicity and anabolism, but head-to-head trials show no consistent clinical superiority for raising plasma arginine or improving performance. AAKG is considerably more expensive per gram of arginine equivalent.
  • L-Arginine HCl vs. L-Citrulline: Citrulline is the clear winner for sustained plasma arginine elevation, producing ~4–6 hours of elevated arginine vs. ~1–2 hours for oral arginine. Citrulline is preferred for endurance exercise, endothelial support, and erectile function. Arginine HCl retains utility for acute clinical use, rapid bolus scenarios, perioperative immunonutrition, and IV diagnostic protocols where direct arginine delivery is required.
  • When to prefer L-Arginine HCL: Clinical or diagnostic IV use; cost-sensitive formulations; perioperative immunonutrition requiring defined arginine content; stack combinations with citrulline for synergistic effects.
  • Natural food alternatives (arginine-rich foods): Pumpkin seeds (~5 g/100 g), chicken breast (~1.4 g/100 g), peanuts (~3.5 g/100 g), soybeans (~3.2 g/100 g), lentils (~2.1 g/100 g) β€” effective for general nutritional arginine intake but impractical for acute therapeutic dosing.

βœ… Quality Criteria and Product Selection (US Market)

In 2024–2026 independent testing by ConsumerLab found that amino acid supplements frequently fail label claims for actual content β€” making third-party certification the single most important quality indicator when purchasing L-Arginine HCL in the US market.

Essential quality criteria to verify before purchasing:

  • Certificate of Analysis (CoA): Confirms L-arginine content (target β‰₯98% purity), enantiomeric purity (L-form only), heavy metals (lead, arsenic, cadmium, mercury below USP limits), microbial limits, and moisture content
  • Third-party certifications to prioritize:
    • USP Verified β€” pharmacopeial-grade purity and dissolution
    • NSF Certified for Sport β€” critical for competitive athletes to avoid banned substance contamination
    • ConsumerLab Approved β€” independent label claim verification
    • cGMP manufacturing β€” FDA-required for dietary supplements
  • Label transparency: Dose expressed in elemental arginine equivalents (not just "as HCl salt"); no hidden proprietary blends obscuring arginine amount

Reputable US brands (not exhaustive):

  • Thorne Research β€” pharmaceutical-grade, NSF Certified for Sport, preferred by healthcare professionals
  • NOW Foods β€” cost-competitive, in-house and third-party testing, widely available
  • Jarrow Formulas β€” reputable manufacturing standards
  • Life Extension β€” clinical focus, regular third-party testing
  • BulkSupplements β€” affordable bulk powder; requires buyer verification of CoA

Red flags to avoid: No accessible CoA; disease-treatment claims on label (prohibited under DSHEA); undisclosed proprietary blends; no third-party certification for athlete products; unrealistic promises of immediate muscle gain or "cure" for medical conditions.

US market pricing (2025–2026):

  • Budget ($10–25/month): Basic powder or capsules from mass-market brands
  • Mid-range ($25–50/month): Branded third-party tested formulations
  • Premium ($50–100+/month): Pharmaceutical-grade, NSF certified, or specialized clinical-stack formulations

Top US retail channels: Amazon, iHerb, Vitacost, GNC, The Vitamin Shoppe, Thorne direct/professional channels, and specialty clinical nutrition suppliers for hospital-grade immunonutrition formulas.

πŸ“ Practical Tips for US Consumers

  • Start low, go slow: Begin at 2–3 g/day to assess GI tolerance before increasing toward therapeutic targets; divide doses to reduce GI impact
  • Timing matters for your goal: Pre-exercise (30–90 min before, fasted if possible) for blood flow; split doses twice daily for blood pressure/endothelial support; before bed for GH-related goals (limited evidence)
  • Consider pairing with citrulline: A 2 g citrulline + 2–3 g arginine HCl combination provides both a rapid arginine peak and sustained elevation β€” the best of both molecules
  • Protect your eNOS with antioxidants: Vitamin C (500–1000 mg/day) helps preserve BH4 and prevent eNOS uncoupling β€” making your arginine work harder
  • Disclose to your physician: Especially if taking any cardiovascular medication (antihypertensives, nitrates), blood thinners, or if you have recurrent herpes infections
  • Hydrate adequately: Amino acid supplements at higher doses can increase urea production and mild diuretic effect β€” maintain standard hydration
  • Evaluate your results: Allow 4–8 weeks before assessing efficacy for most outcomes; request a CoA from any supplier upon request β€” reputable brands provide this readily

🎯 Conclusion: Who Should Take L-Arginine HCL?

L-Arginine HCL represents one of the most biochemically versatile and well-characterized amino acid supplements available β€” with the strongest evidence supporting its use in endothelial dysfunction, mild vasculogenic erectile dysfunction, blood pressure management, and perioperative wound healing at doses of 3–6 g/day.

Ideal candidates include: adults with measurable endothelial dysfunction or prehypertension seeking non-pharmacological adjunctive support; men with mild-to-moderate vasculogenic erectile dysfunction (ideally combined with antioxidants or prescribed PDE5 therapy under physician guidance); recreational athletes seeking acute pre-workout muscle perfusion benefits; and surgical patients receiving specialist-designed immunonutrition protocols.

Those for whom L-arginine HCL is less ideal: individuals seeking sustained arginine elevation for endurance sports (choose L-citrulline as primary agent); patients on nitrates or PDE5 inhibitors without physician oversight (serious hypotension risk); people with recurrent HSV infections; and individuals with severe renal or hepatic impairment.

The supplement market is flooded with arginine-containing products of variable quality. Choosing a product with NSF Certified for Sport or USP Verified status, transparent CoA, and clearly labeled elemental arginine content is essential to ensure you receive what is promised on the label. As always, consultation with a qualified healthcare provider β€” particularly a physician or registered dietitian β€” before initiating therapeutic-dose supplementation is strongly recommended, especially in the context of existing medical conditions or medications.

Science-Backed Benefits

Improvement of endothelial function (vasodilation)

◐ Moderate Evidence

Arginine serves as the substrate for endothelial nitric oxide synthase (eNOS) producing nitric oxide (NO), a vasodilator that relaxes vascular smooth muscle and improves endothelial-dependent vasodilation, microcirculatory blood flow and perfusion.

Erectile function support (mild-to-moderate erectile dysfunction)

◐ Moderate Evidence

Erection physiology depends on endothelial-derived NO to relax cavernosal smooth muscle and increase penile blood flow. Supplementation can increase systemic and local arginine substrate levels for NO production.

Blood pressure reduction (modest)

βœ“ Strong Evidence

Increased NO production promotes vasodilation and reduces systemic vascular resistance, leading to modest reductions in systolic and diastolic blood pressure.

Exercise performance and muscle perfusion (short-term ergogenic aide)

β—― Limited Evidence

Arginine-derived NO increases muscle blood flow, substrate delivery and may support oxygen delivery during exercise; arginine also stimulates mTORC1 signaling which can support anabolic responses in presence of resistance exercise and nutrients.

Wound healing and post-operative recovery

◐ Moderate Evidence

Arginine provides substrate for proline and polyamine synthesis via ornithine, supporting collagen formation and cell proliferation. It also stimulates immune functions and NO-mediated perfusion at wound sites, important for healing.

Immune support and modulation (context-dependent)

β—― Limited Evidence

Arginine availability influences macrophage function, T-cell proliferation and NO-mediated antimicrobial activity. Adequate arginine supports lymphocyte proliferation and function; however, in some inflammatory states arginine metabolism is dysregulated.

Pulmonary vascular effects (adjunctive in pulmonary hypertension / hypoxic vasoconstriction contexts)

β—― Limited Evidence

NO is a pulmonary vasodilator; arginine provision may augment NO production in pulmonary endothelium, lowering pulmonary artery pressures in some contexts.

Stimulation of growth hormone (GH) secretion (endocrine modulation)

βœ“ Strong Evidence

Arginine suppresses hypothalamic somatostatin release, disinhibiting GH secretion. Intravenous arginine is used diagnostically in GH stimulation tests.

πŸ“‹ Basic Information

Classification

Amino acid (dietary supplement / nutraceutical) β€” Basic (cationic) amino acid; semi-essential / conditionally essential

Active Compounds

  • β€’ Powder (bulk)
  • β€’ Capsules (L-Arginine HCl)
  • β€’ Tablets
  • β€’ Liquid solutions (oral or parenteral)
  • β€’ Salt derivatives (AAKG, ethyl ester)

Alternative Names

L-Arginin-HydrochloridL-Arginine HClArginine hydrochloride2-Amino-5-guanidinopentanoic acid hydrochlorideArg HCl

Origin & History

Arginine per se does not have a long traditional medicine history as a distinct isolated agent (it is a constituent of protein-rich foods used across cultures). Traditional diets rich in meat, nuts and legumes provided arginine indirectly. Specific therapeutic use of isolated arginine emerged with modern nutrition science (20th century).

πŸ”¬ Scientific Foundations

⚑ Mechanisms of Action

Endothelial cells (eNOS substrate), Vascular smooth muscle (NO-mediated cGMP signaling), Immune cells (macrophage iNOS regulation), Hepatocytes/urea cycle enzymes (arginase), Skeletal muscle cells (mTOR nutrient-sensing)

πŸ“Š Bioavailability

Highly variable between individuals and dose ranges; systemic bioavailability of orally administered arginine is limited by splanchnic extraction. Representative literature ranges commonly cited: ~20–60% bioavailability (dependent on dose, co-ingestion, and first-pass metabolism).

πŸ’Š Available Forms

Powder (bulk)Capsules (L-Arginine HCl)TabletsLiquid solutions (oral or parenteral)Salt derivatives (AAKG, ethyl ester)

✨ Optimal Absorption

Carrier-mediated uptake through cationic amino acid transporters (particularly CAT family: SLC7A1/CAT-1, SLC7A2/CAT-2A/2B and y+ transporters). Also taken up into enterocytes where significant splanchnic (first-pass) metabolism can occur.

Dosage & Usage

πŸ’ŠRecommended Daily Dose

Typical Supplement Range: 2–6 g/day oral β€’ Common Over The Counter: 500 mg – 1 g capsules/tablets; dosing commonly 1–3 g two or three times daily

Therapeutic range: 1 g/day (minimal supplemental doses) – up to 9 g/day commonly used in clinical trials for selected endpoints; some studies administer single bolus doses of 10–20 g acutely but with increased GI side effects

⏰Timing

Not specified

L-arginine - Mayo Clinic

2025-06-28

Mayo Clinic overview states L-arginine acts as a vasodilator, potentially lowering blood pressure in healthy individuals, those with mild hypertension, diabetes, and pulmonary hypertension. Research indicates it may decrease angina symptoms, improve quality of life, and aid erectile dysfunction due to physical causes. It is generally considered safe but consultation with a doctor is advised if on blood pressure medications.

πŸ“° Mayo ClinicRead Studyβ†—

L-arginine: Benefits, Dosage, Side Effects, and More - Healthline

2025

A 2025 review cited by Healthline suggests L-arginine supplements may improve pregnancy outcomes and fetal health. Potential benefits include enhancing athletic performance, managing infections like COVID-19, promoting wound healing, improving erectile dysfunction symptoms, and preventing preeclampsia, though research remains limited and inconclusive. L-citrulline may be more effective at raising arginine levels.

πŸ“° HealthlineRead Studyβ†—

Effect of Add-on L-Arginine Therapy on Heart Failure Patients

2025

Ongoing clinical trial investigates 6g daily L-arginine supplementation versus placebo in heart failure patients over 6 weeks. Primary outcomes include changes in global longitudinal strain (GLS), NYHA classification, exercise capacity via ECG, NT-proBNP levels, quality of life, safety via MAP and HR, and endothelial biomarkers like endothelin-1 and ADMA. Sponsored by Ain Shams University.

πŸ“° ClinicalTrials.govRead Studyβ†—

Safety & Drug Interactions

⚠️Possible Side Effects

  • β€’Gastrointestinal upset (nausea, abdominal pain, diarrhea)
  • β€’Flatus and bloating
  • β€’Hypotension (dizziness, lightheadedness)
  • β€’Herpes simplex reactivation (theoretical/observational)

πŸ’ŠDrug Interactions

High

Pharmacodynamic (additive vasodilation)

Medium–High

Pharmacodynamic (additive hypotensive effect)

Medium

Pharmacodynamic (additive blood pressure lowering)

Low–Medium

Pharmacodynamic (theoretical increased bleeding risk)

Low–Medium

Pharmacological/modulatory (theoretical immune modulation)

Low

Absorption / administration timing

Medium (for patients with recurrent HSV infections)

Pharmacological (clinical caution rather than direct interaction)

🚫Contraindications

  • β€’Concurrent use with organic nitrates (e.g., nitroglycerin) without strict medical supervision due to risk of severe hypotension
  • β€’Known hypersensitivity to arginine-containing products or to excipients in the formulation

Important: This information does not replace medical advice. Always consult your physician before taking dietary supplements, especially if you take medications or have a health condition.

πŸ›οΈ Regulatory Positions

πŸ‡ΊπŸ‡Έ

FDA (United States)

Food and Drug Administration

L-arginine is not an FDA-approved drug for general indications; it is sold as a dietary supplement under DSHEA. The FDA monitors safety and labeling; disease treatment claims are prohibited for supplement labeling. Parenteral arginine-containing products and clinical nutrition formulations are regulated under different pathways (medical foods, prescription formulations).

πŸ”¬

NIH / ODS (United States)

National Institutes of Health – Office of Dietary Supplements

The National Institutes of Health (NIH) Office of Dietary Supplements provides background on amino acids and nutrients. L-arginine is recognized as conditionally essential in some contexts; clinical guidance varies by indication. The NIH/other federal bodies encourage consultation with healthcare professionals for therapeutic use.

⚠️ Warnings & Notices

  • β€’Avoid combining arginine supplements with nitrates or using with PDE5 inhibitors without clinical advice due to hypotension risk.
  • β€’Individuals with active herpes simplex infections should use arginine cautiously; consider medical guidance.
βœ…

DSHEA Status

Classified and marketed as a dietary supplement ingredient under DSHEA when sold as OTC supplement. Clinical/therapeutic formulations may fall outside simple DSHEA categorization (medical foods, parenteral nutrition).

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease.

πŸ‡ΊπŸ‡Έ US Market

πŸ“Š

Usage Statistics

Specific up-to-date prevalence data for L-arginine supplementation in the US population are limited; general amino acid supplement use (including arginine) is a minority behaviorβ€”estimates suggest low-single-digit percent of adults use arginine-specific supplements regularly. Prevalence is higher among athletes and certain patient groups (postoperative, cardiovascular disease adjunctive).

πŸ“ˆ

Market Trends

Growing interest in NO-boosting supplements (including arginine and citrulline), with a trend favoring citrulline for endurance/ergogenic claims. Demand for clinically tested immunonutrition formulas containing arginine remains steady in hospital/perioperative markets.

πŸ’°

Price Range (USD)

Budget: $10–25 for basic powder/capsule supplies (1 month at low dose); Mid: $25–50/month for branded formulations; Premium: $50–100+/month for pharmaceutical-grade, third-party tested clinical formulas or combined stacks.

Note: Prices and availability may vary. Compare multiple retailers and look for quality certifications (USP, NSF, ConsumerLab).

βš•οΈMedical Disclaimer

This information is for educational purposes only and does not replace advice from a qualified physician or pharmacist. Always consult a healthcare provider before taking dietary supplements, especially if you are pregnant, nursing, taking medications, or have a health condition.

πŸ“šScientific Sources

Last updated: February 22, 2026