The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.


Avoid with known allergy or sensitivity to arginine. Symptoms may include rash, itching, or shortness of breath. Anaphylaxis (severe allergic reaction) has occurred after arginine injections. In clinical research, one patient experienced a mild allergic skin reaction to intravenous L-arginine. Hives have also been reported.

Side Effects and Warnings

Note: According to the U.S. Food and Drug Administration (FDA) website, pediatric overdose of arginine hydrochloride injection (R-Gene 10®) has been reported, due to packaging and labeling confusion. Revisions have since been made to the product's packaging. The new label warns that R-Gene 10® infusions should be used cautiously in children to prevent overdose, which may result in hyperchloremic metabolic acidosis, cerebral edema, or possibly death.

Arginine is likely safe when taken in levels normally found in foods.

Arginine may increase the risk of bleeding. Caution is advised in people with bleeding disorders or those taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Arginine may change blood sugar levels. Caution is advised in people with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.

Arginine may cause hyperkalemia (abnormally high levels of blood potassium). Use cautiously in people with impaired kidney function or those at risk for hyperkalemia, including those with diabetes or using drugs that elevate potassium levels, such as potassium-sparing diuretics and potassium supplements. Fatal cardiac arrhythmias from hyperkalemia occurred in one person.

Use cautiously in children and in pregnant women, due to insufficient available evidence and safety data.

Use caution with phosphodiesterase inhibitors (e.g., sildenafil [Viagra®]).

Use with caution in postmenopausal women or people with the herpes virus, peripheral arterial disease and intermittent claudication, immune disorders, acrocyanosis (blue coloring of hands and feet), sickle cell anemia, hyperchloremic acidosis (acid-base imbalance in the body), gastrointestinal problems, muscle or joint problems, urinary disorders, asthma, cycstic fibrosis, methyltransferase (GAMT) deficiency (a genetic disorder), or at risk for headaches.

Avoid with known allergy or sensitivity to arginine.

Avoid in doses over 30 grams due to increased risk of toxic effects.

Avoid in women with high-risk pregnancies, as, in women with multiple diseases, intravenous arginine resulted in premature delivery, pre-eclampsia, and death in two cases.

Arginine may cause low blood pressure. Avoid use in those with low blood pressure or those using blood pressure-lowering agents.

Avoid with nitrates and spironolactone as well as in people with pulmonary hypertension, cancer, and those at risk for or with a history of heart attack.

Arginine may also cause bloating; diarrhea; hematuria (blood in urine), hives; hormonal changes; increased blood urea nitrogen, serum creatine, and serum creatinine; increased inflammatory response (in people with asthma or cystic fibrosis); leg restlessness, lower back pain; nausea, night sweats and flushing (with arginine withdrawal), numbness (with arginine injection); rash; reduction in hematocrit; severe tissue damage (with arginine injection); stomach and intestine discomfort; systemic acidosis; or venous irritation.

In people with heart disease or heart transplants, arginine may cause high white blood cell counts, increased post-heart attack deaths, lack of energy and strength, vertigo, or increased blood pressure.

Pregnancy and Breastfeeding

Use cautiously in pregnant or breastfeeding women, due to a lack of sufficient available safety and efficacy data.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration