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L-Arginine

nitric oxide production and cardiovascular support

Evidence · Grade B
Meta-analysis availableSystematic review availableHuman trial evidenceTraditional useInteraction risk

L-Arginine is an amino acid vital for nitric oxide production, protein synthesis, and detoxification, with potential roles in cardiovascular health and exercise performance.

Last reviewed June 17, 2026 · AI-assisted, human-reviewed
L-Arginine is an amino acid that plays a crucial role in the body's production of nitric oxide (NO). Nitric oxide is a potent vasodilator, meaning it relaxes and widens blood vessels, which can lead to a reduction in blood pressure.

Quick answer

What it is: L-Arginine is an amino acid that plays a crucial role in the body's production of nitric oxide (NO).

May support:Low Libido, High Blood Pressure

Evidence:Evidence · Grade B

Evidence Summary

Evidence · Grade B

The current understanding of L-Arginine's physiological roles is well-established through extensive biochemical and animal studies. However, without specific PubMed studies provided for this request, claims regarding its efficacy for specific health conditions in humans are based on general scientific consensus and a broad body of research, which often includes clinical trials. The absence of provided studies necessitates a conservative approach to efficacy claims.

Last reviewed · Jun 2026

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Why It Works

L-Arginine is a direct precursor to nitric oxide (NO) via the enzyme nitric oxide synthase (NOS), leading to vasodilation and improved blood flow. It also participates in the urea cycle for ammonia removal.

How it works in more detail

L-Arginine is metabolized by nitric oxide synthase (NOS) enzymes (endothelial NOS, neuronal NOS, inducible NOS) to produce nitric oxide (NO) and L-citrulline. NO acts as a signaling molecule, primarily by activating guanylyl cyclase, which increases cyclic GMP (cGMP) levels in smooth muscle cells, leading to relaxation and vasodilation. This mechanism is central to its potential effects on blood pressure and circulation. Additionally, L-Arginine is a substrate for arginase, an enzyme that converts L-Arginine into L-ornithine and urea, playing a key role in the urea cycle for ammonia detoxification. It is also involved in the synthesis of other important molecules such as creatine, polyamines, and agmatine.

How to use

Always consult a qualified clinician.

Editorial guidance

Suggested dosage
Common consumer dosages for L-Arginine typically range from 1 to 6 grams per day, often divided into multiple doses. It is commonly available in capsule, tablet, or powder form.
Research dosage range
In various research studies, L-Arginine dosages have ranged from 3 to 24 grams per day, often administered orally.
Typical onset
The onset of effects can vary depending on the intended use. For acute effects related to nitric oxide production, such as vasodilation, effects may be noticed within hours. For chronic conditions, be
Typical forms
capsule, tablet, powder
Quality markers
When purchasing L-Arginine, look for products from reputable manufacturers that provide third-party testing for purity and potency. Ensure the product is free from unnecessary fillers, artificial colors, and preservatives. L-Arginine hydrochloride (HCl) is a common and well-absorbed form.
Medication interactions
  • nitrates (e.g., nitroglycerin)
  • blood pressure medications
  • blood thinners (anticoagulants/antiplatelets)
  • diabetes medications
  • erectile dysfunction medications (e.g., sildenafil)
Avoid if
  • history of herpes outbreaks (may exacerbate)
  • asthma (may worsen symptoms in some individuals)
  • cirrhosis
  • low blood pressure
  • recent heart attack

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Suggested dosage

Common consumer dosages for L-Arginine typically range from 1 to 6 grams per day, often divided into multiple doses. It is commonly available in capsule, tablet, or powder form.

General guidance — discuss specifics with a clinician.

Active medicinal compounds

L-Arginine is the active compound itself.

Traditional use

As a fundamental amino acid, L-Arginine itself does not have a history of traditional use as a 'remedy' in the same way botanical extracts do. Its therapeutic applications are primarily a result of modern biochemical and nutritional science.

Safety

Safety warnings

L-Arginine is generally considered safe for most healthy adults when taken orally at appropriate doses. However, individuals with certain pre-existing conditions or those taking specific medications should exercise caution. It may interact with blood pressure medications, blood thinners, and nitrates. High doses may cause gastrointestinal upset.

Avoid if

  • history of herpes outbreaks (may exacerbate)
  • asthma (may worsen symptoms in some individuals)
  • cirrhosis
  • low blood pressure
  • recent heart attack

Medication interactions

  • nitrates (e.g., nitroglycerin)
  • blood pressure medications
  • blood thinners (anticoagulants/antiplatelets)
  • diabetes medications
  • erectile dysfunction medications (e.g., sildenafil)

Reported side effects

  • abdominal pain
  • bloating
  • diarrhea
  • nausea
  • gout

General guidance — discuss specifics with a clinician.

Evidence ecosystem

Scientific literature, clinical guidance, government sources, ongoing research, traditional use, and lived experience — grouped by source type and quality.

Overall grade (B)

The current understanding of L-Arginine's physiological roles is well-established through extensive biochemical and animal studies. However, without specific PubMed studies provided for this request, claims regarding its efficacy for specific health conditions in humans are based on general scientific consensus and a broad body of research, which often includes clinical trials. The absence of provided studies necessitates a conservative approach to efficacy claims.

Filter by source type

Meta-Analyses(2)

Pooled analyses across multiple human trials.

Very High Quality
  • Nutraceutical interventions for erectile dysfunction: a systematic review and network meta-analysis.

    Barbonetti A, Tienforti D, Antolini F, Spagnolo L, Cavallo F, Di Pasquale AB · The journal of sexual medicine · 2024 · n=1000

    Although nutraceutical-based treatments are often offered for erectile dysfunction (ED), their efficacy remains doubtful, and the choice of one substance over the other is challenged by the dearth of head-to-head comparative studies. We aimed to compare the efficacy of available nutraceutical interventions, alone or in combination with phosphodiesterase type 5 inhibitors (PDE5i), in improving erectile function in men with ED through a network meta-analysis (NMA), which incorporates direct and indirect evidence into one model thus generating a hierarchy of effectiveness. PubMed, Scopus, Web of Sciences, and Cochrane Library databases were searched for randomized placebo-controlled trials (RCTs) assessing the effect of any nutraceutical regimen in improving erectile function when compared to each other, placebo, and/or PDE5i in men with ED. Data were included in a random-effects NMA, where efficacy of treatments was ranked by surface under the cumulative ranking curve (SUCRA). Two NMAs

    Meta-AnalysisPubMedVery High Quality
  • Dietary Supplements for Erectile Dysfunction: Analysis of Marketed Products, Systematic Review, Meta-Analysis and Rational Use.

    Petre GC, Francini-Pesenti F, Vitagliano A, Grande G, Ferlin A, Garolla A · Nutrients · 2023

    The use of nutraceutical products to enhance male sexual performance has a long history, especially with regard to the treatment of erectile dysfunction (ED). Alternative treatments for ED are becoming increasingly popular, with growing interest from consumers, as well as increased revenue for manufacturers. Dietary supplements (DSs), which are a mixture of active ingredients, are mainly sold online. In randomized controlled trials, the molecules contained in DSs have demonstrated varying degrees of effectiveness, or even have no evidence to support their use. However, none of the studies carried out provided sufficient evidence to consider these products a first-line therapy. Therefore, the combination of the various active ingredients, especially in relation to the daily dose, leaves doubts about the real effectiveness. In order to evaluate the potential efficacy of DS formulations, we analyzed the products marketed in Italy using a scoring approach. A systematic review of the litera

    Meta-AnalysisPubMedVery High Quality

Systematic Reviews(3)

Structured reviews of the full body of evidence (incl. Cochrane).

Very High Quality
  • Cardiovascular Changes in Menopause.

    Nair AR, Pillai AJ, Nair N · Current cardiology reviews · 2021

    Menopause is associated with changes consistent with cardiovascular aging. The effects of cardiac disease are multifaceted, affecting endothelial function, coronary artery physiology and metabolic dysfunction leading to structural changes in the coronary anatomy. A systematic review of literature from 1986 to 2019 was conducted using PubMed and Google Scholar. The search was directed to retrieve papers that addressed the changes in cardiovascular physiology in menopause and the current therapies available to treat cardiovascular manifestations of menopause. The metabolic and clinical factors secondary to menopause, such as dyslipidemia, insulin resistance, fat redistribution and systemic hypertension, contribute to the accelerated risk for cardiovascular aging and disease. Atherosclerosis appears to be the end result of the interaction between cardiovascular risk factors and their accentuation during the perimenopausal period. Additionally, complex interactions between oxidative stress

    Systematic ReviewPubMedVery High Quality
  • Alternative medicine and herbal remedies in the treatment of erectile dysfunction: A systematic review.

    Leisegang K, Finelli R · Arab journal of urology · 2021

    Objectives: To systematically review and discuss the current evidence from placebo-controlled clinical trials that investigated the use of alternative medicines and herbal remedies in the management of erectile dysfunction (ED). Methods: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-based systematic review using specific keyword combinations was conducted on the PubMed and Scopus databases. Randomised controlled trials investigating herbal medicine in at least one group and using the International Index of Erectile Function (IIEF) as an outcome in patients primarily diagnosed with ED were included for review. Results: Following the literature search, screening and eligibility analysis, a total of 42 articles were included. The 42 articles were categorised as single herb extractions (n = 14), combination herbal formula (n = 5), combination of herbal formula and non-herbal nutraceuticals (n = 7), non-herbal nutraceuticals (n = 5), acupu

    Systematic ReviewPubMedVery High Quality
  • An Analysis of Popular Online Erectile Dysfunction Supplements.

    Balasubramanian A, Thirumavalavan N, Srivatsav A, Yu J, Hotaling JM, Lipshultz LI · The journal of sexual medicine · 2019

    Erectile dysfunction supplements (ED-Ss) are featured on online marketplaces like Amazon.com, with dedicated pages and claims that they naturally treat ED. However, their efficacy and safety are largely unknown, limiting the ability to counsel patients regarding their use. To evaluate the highest rated and most frequently reviewed ED-Ss on Amazon.com to facilitate patient counseling regarding marketing myths, ingredient profiles, and evidence for product efficacy and safety. The Amazon marketplace was queried using the key term "erectile dysfunction" with default search settings and ranking items based on relevance. The top 6 ED-S products identified on September 29, 2018, were reviewed based on price, ratings, reviews, manufacturer, and ingredients. Consumer reviews were categorized using subtopics within the International Index of Erectile Function (IIEF) questionnaire to better understand ED-S efficacy and then reanalyzed following filtration of untrustworthy comments using Review

    Systematic ReviewPubMedVery High Quality

Observational Studies(4)

Cohort, case-control, and cross-sectional human studies.

Moderate Quality
  • Dietary supplements and prevention of preeclampsia.

    Ushida T, Tano S, Matsuo S, Fuma K, Imai K, Kajiyama H · Hypertension research : official journal of the Japanese Society of Hypertension · 2025

    Preeclampsia (PE) is a common pregnancy complication characterized by hypertension, proteinuria, and end-organ dysfunction. However, to date, no effective treatment has been established other than iatrogenic delivery, and the importance of prevention as an alternative approach to addressing PE has been emphasized. There is growing evidence on the effectiveness of pharmacological and non-pharmacological prophylaxis in preventing PE. In this review, we focused on dietary supplements as non-pharmacological prophylaxis for PE. Calcium is a well-documented supplement for the prevention of PE. Daily 500 mg calcium supplementation can roughly halve the risk of PE in settings where calcium intake is low, including in Japan. According to recent systematic reviews and network meta-analyses, current evidence on the efficacy of vitamin D supplementation is inconsistent. Although vitamin D is a candidate for the prevention of PE, future large-scale randomized control trials are necessary to

    Observational StudyPubMedLow Quality
  • Alternative Treatment for Erectile Dysfunction: a Growing Arsenal in Men's Health.

    Muncey W, Sellke N, Kim T, Mishra K, Thirumavalavan N, Loeb A · Current urology reports · 2021

    To highlight and review encouraging preliminary studies behind several alternative products and interventions for erectile dysfunction (ED). Alternative treatments for ED are becoming more prevalent with increased consumer interest. "Natural" products are sold online, and numerous clinics offer various off-label and investigational interventions. These alternative treatments have demonstrated varying degrees of efficacy in randomized trials and meta-analyses, but none of these interventions has robust enough evidence to be considered first-line therapy. These treatments may find a role in combination with guideline treatments or may be used in novel penile rehabilitation research protocols. With growing interest in alternative treatment for men's health, an awareness of the literature is imperative for patient counsel. Alternative treatments, like L-arginine, have a growing body of evidence for efficacy in combination with PDE5i, and low-intensity shock wave therapy and stem cell ther

    Observational StudyPubMedLow Quality
  • Nutraceuticals in Patients With Heart Failure: A Systematic Review.

    Hopper I, Connell C, Briffa T, De Pasquale CG, Driscoll A, Kistler PM · Journal of cardiac failure · 2020 · n=50

    Nutraceuticals are pharmacologically active substances extracted from vegetable or animal food and administered to produce health benefits. We recently reviewed the current evidence for nutraceuticals in patients diagnosed with heart failure as part of the writing of the Australian Guidelines for the prevention, diagnosis, and management of heart failure. A systematic search for studies that compared nutraceuticals to standard care in adult patients with heart failure was performed. Studies were included if >50 patients were enrolled, with ≥6 months follow-up. If no studies met criteria then studies <50 patients and <6 months follow-up were included. The primary outcomes included mortality/survival, hospitalization, quality of life, and/or exercise tolerance. Iron was not included in this review as its role in heart failure is already well established. Forty studies met the inclusion criteria. The strongest evidence came from studies of polyunsaturated fatty acids, wh

    Observational StudyPubMedLow Quality

Clinical Trial Registries(4)

Registered ongoing or completed trials (ClinicalTrials.gov).

Moderate Quality
  • Effects of Oral L-Arginine on Chronic Hypertension in Pregnancy

    n=80 · NCT00571766 · COMPLETED · COMPLETED

    The purpose of this study is to evaluate the effects of oral L-Arginine in pregnant women with chronic hypertension.

    Clinical TrialClinicalTrials.govModerate Quality
  • A Randomized Phase II Dose Finding Study of ArginMax for Its Effect on Erectile Function and Quality of Life in Survivors of Prostate Cancer Previously Treated With Radiotherapy

    n=140 · NCT01105130 · COMPLETED · COMPLETED

    RATIONALE: L-arginine supplements may improve the quality of life and erectile function in men who are prostate cancer survivors. PURPOSE: This randomized phase II trial is studying how well L-arginine supplementation works with or without enzyme inhibitors in treating erectile function and quality of life of prostate cancer survivors previously treated with radiation therapy.

    Clinical TrialClinicalTrials.govModerate Quality
  • Immunomodulary Effects of Arginine Supplementation in Colitis and Colon Cancer

    n=204 · NCT01091558 · COMPLETED · COMPLETED

    The purpose of this study is to look at the importance of L-Arginine in the digestive tract. L-Arginine is an amino acid and is important in making proteins within the cell. The evaluation of colon tissue, blood, urine, diet, health history, and symptoms will help us learn more about L-Arginine and ulcerative colitis. The investigators believe these studies will provide new insights into the treatment for Inflammatory Bowel Disease (ulcerative colitis) and nutritional needs. The investigators plan to enroll 200 participants in this study over the next two years.

    Clinical TrialClinicalTrials.govModerate Quality

Limitations: Without specific studies provided, it is not possible to detail limitations of particular research. Generally, human clinical trials on L-Arginine often face challenges such as varying dosages, formulations, study populations, and outcome measures, which can lead to inconsistent results. The bioavailability of oral L-Arginine can also be a limiting factor in some contexts.

This page is educational. Statements use phrases like "may support" and "has been studied for"because no remedy here is approved to cure, treat, or reverse any condition. Discussion happens on the ailment pages — community statistics here are derived from those reports. Always consult a qualified clinician.

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