Natural Health Products

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General Information

L-arginine was first isolated in 1886. It is an amino acid, which is a chemical building block to make proteins. The body usually makes enough L-arginine, but occasionally supplementation is needed. L-arginine can be found in red meat, poultry, fish, and dairy products.

L-arginine is converted in the body into a chemical called nitric oxide. Nitric oxide improves blood flow by relaxing and widening blood vessels. L-arginine also stimulates the release of other substances in the body, such as growth hormones, prolactin, and insulin.

Common Name(s)
Scientific Name(s)

(s)-2-Amino-5-[(aminoiminomethyl)amino] pentanoic acid, L-arginine

How is this product usually used?

L-arginine can be extracted from natural sources or made in the laboratory.

It is made into supplements of different forms such as chewable tablets/gummies, caplets, capsules, lozenges, powders, strips, and liquids.

The dose for L-arginine ranges from 6 g to 21 g per day, with no more than 8 g in a single dose for improving exercise capacity in individuals with stable cardiovascular diseases. For protein synthesis, smaller doses may be recommended (0.21 g to 21 g per day).

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

What is this product used for?

L-arginine may help people with stable cardiovascular (heart) diseases to be able to exercise more. It is also a non-essential amino acid that is involved in protein synthesis in the body.

Research suggests that L-arginine may be helpful for those with heart conditions such as coronary artery disease, angina, clogged arteries, or atherosclerosis (hardening of arteries) and for those with peripheral vascular diseases. It is effective as a protein synthesis supplement.

People have also used L-arginine to prevent the common cold, improve kidney function after kidney transplant, improve athletic performance, boost the immune system, prevent loss of effect of nitroglycerin, and improve pre-eclampsia (high blood pressure during pregnancy). It has also been used by people for erectile dysfunction, male infertility, dementia, and many other problems. However, there is not enough high-quality evidence available to assess the use of L-arginine in these conditions. Additional research is needed to confirm its benefits.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What else should I be aware of?

L-arginine is likely safe when taken in levels normally found in foods. Side effects sometimes seen include stomach upset, nausea, diarrhea, bloating, headache, difficulty sleeping, and flushing. If you experience a severe allergic reaction to L-arginine (swelling of face and throat, difficulty breathing), stop using the supplement and seek medical help right away.

If you have any sort of cardiovascular disease, speak with your doctor about using L-arginine, especially if you are using it for more than 6 weeks. In general, you should not take L-arginine beyond 3 to 6 months without consulting a health care provider. If your condition worsens at any time, see your doctor. If you have kidney diseases, talk to your doctor before you start.

There have been reports of increased rates of death following a heart attack when L-arginine (3 g of L-arginine 3 times daily for 6 months) is added to standard post-heart-attack medications. If you have recently had a heart attack, do not use L-arginine supplements.

Since L-arginine can be converted to nitric oxide in your body and can add to the blood-lowering effects of nitrate medications (e.g., nitroglycerin), it may cause your blood pressure to drop too low when taken with other blood-pressure-lowering medications, and may increase the risk of dizziness and lightheadedness. Do not take L-arginine with blood-pressure-lowering medications without first speaking with your doctor.

L-arginine may increase the risk of bleeding and therefore should be used with caution by people with bleeding disorders or taking drugs with similar properties (e.g., anticoagulants).

L-arginine may also change blood sugar levels. Individuals with diabetes or taking diabetic medications should use it with care.

L-arginine can cause vasodilation (widening of the blood vessels) and may increase blood-pressure lowering effect of erectile dysfunction drugs such as sildenafil.

It is not known how safe L-arginine is for use by pregnant and breast-feeding women. Talk to your doctor before using this supplement if you are pregnant or breast-feeding.

L-arginine can interact with the following medications:

  • anticoagulants (e.g., warfarin, heparin)
  • diabetic medications
  • garlic
  • ginkgo biloba
  • medications that lower blood pressure (e.g., nitrates, sildenafil)
  • saw palmetto
  • potassium-sparing diuretics

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.

  1. Health Canada. Drugs & Health Products. Monograph – Arginine, L-.
  2. Natural Medicines Comprehensive Database. L-Arginine.

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