L-Arginine Safety, Risk of Adverse Effects and Interactions

L-arginine is obtained by breaking down proteins, and can also be synthesized in the laboratory.

Because L-arginine may be synthesized in the body, it is classified as a non-essential amino acid.

L-arginine is used for heart and blood vessel conditions including congestive heart failure, chest pain, high blood pressure, and coronary artery disease.

The body is capable of manufacturing this compound, L-Arginine, but it may need to be supplemented in certain conditions.

It is used as a dietary supplement to improve athletic capacity, muscle growth, sexual performance, fertility, cognitive abilities, and cardiovascular function.

It is also used to stimulate the immune system.

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How Does it Work?

L-arginine is converted in the body into nitric oxide, which causes blood vessels to open wider for improved blood flow.

L-arginine also stimulates the discharge of growth hormone, insulin, and other substances in the body.

L-Arginine Safety

Natural Medicines rates L-Arginine as “Possibly Safe” when taken orally and appropriately for a duration of up to 3 months.

Consumption of L-Arginine is generally considered safe, though there may be some side effects linked to it when used as a supplement.

These side effects are not considered dangerous when used at appropriate dosages, but they typically consist of gastrointestinal upset, a reduction in blood pressure or headaches.

L-Arginine can also interact with certain prescription drugs or other dietary supplements, and individuals with certain medical conditions, including allergies, asthma, cirrhosis, Herpes virus, hypotension, myocardial infarction (MI) and renal disease should speak to their doctors before using L-Arginine.


L-arginine as a nonessential amino acid plays an important role in the treatment of heart disease due to its block arterial plaque buildup, blood clots, platelet clumping, and to increase blood flow through the coronary artery.

L-arginine is sold as a health supplement with claims to improve vascular health and treat erectile dysfunction in men.

It is also promoted as a human growth stimulant, has also been used in bodybuilding.

L-arginine serves as a basis for the synthesis of numerous beneficial compounds in the body, such as glutamate, creatinine, urea, polyamines (essential molecules required for the proliferation and differentiation of cells) and another amino acid called proline.

L-arginine is also converted into nitric oxide in the blood, making it functions as a vasodilator.

Vasodilators generally cause blood vessels to expand diametrically.

Expanded blood vessels result in an increase in circulation throughout the body, but without causing blood pressure to rise.

L-arginine is also involved in the synthesis of hormones, structured proteins, and enzymes in the body, helping to aid in the release of insulin, glucagon, growth hormone, and prolactin.

L-arginine is also a precursor to a variety of biological compounds that promote immune system responses and functions.

L-Arginine’s Roles in the Body

Supplementing with L-arginine is believed to be good for wound healing by enhancing the development and growth of blood vessels.

The amino acid also improves blood flow and increases the delivery of oxygen, nitrogen, and other nutrients to important parts of the body, including wound sites.

L-arginine can also have positive benefits for muscle growth and athletic performance.

Because, by increasing the circulation of energy, oxygen, and other nutrients needed to build proteins, it may support improved recovery from workouts as well as muscle building and strength increment.


Absolute contraindications have not been identified, and L-arginine is not recommended in patients following an acute heart attack.


Specific information regarding safety and efficacy during pregnancy and breastfeeding is deficient, although several trials have been conducted in pregnant women, and no notable ill effects were observed.


L-arginine has unpredictable effects on agents that lower insulin and cholesterol. It may increase the effects of isosorbide mononitrate and other nitric oxide donors, such as sodium nitroprusside and glyceryl trinitrate.

Side Effects

L-arginine has few reported adverse reactions that include nausea and diarrhea.

A bitter taste may occur with higher doses, and due to its ability to dilate blood vessels, low blood pressure may also occur.

Intravenous preparations containing L-arginine hydrochloride can have a high chloride content that may increase the risk for metabolic acidosis in patients with electrolyte imbalances.

Low potassium and high serum urea nitrogen levels may even occur in patients with kidney or liver impairment.

As a final note, high concentrations of nitric oxide, which can be produced by L-arginine, are considered toxic to brain tissue.

Best Selling L-Arginine Supplements

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  1. L-arginine. Review of Natural Products. Facts & Comparisons [database online]. St. Louis, MO: Wolters Kluwer Health Inc; October 2010.


L-Arginine Safety

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