Overview

L-arginine is an amino acid naturally found in red meat, poultry, fish, and dairy. It is necessary for making proteins and is commonly used for circulation.

L-arginine is converted in the body into a chemical called nitric oxide. Nitric oxide causes blood vessels to open wider for improved blood flow. L-arginine also stimulates the release of growth hormone, insulin, and other substances in the body. It can be made in a lab and used in supplements.

People use L-arginine for chest pain and various blood flow issues, erectile dysfunction, high blood pressure during pregnancy, and a serious disease in premature infants called necrotizing enterocolitis (NEC). It's also used for many other conditions, but there is no good scientific evidence to support these other uses.

Uses & Effectiveness

Possibly Effective for

  • Chest pain (angina). Taking L-arginine by mouth seems to decrease symptoms and improve exercise tolerance and quality of life in people with angina. But it doesn't seem to help widen blood vessels that are narrowed in angina.
  • Erectile dysfunction (ED). Taking 2.5-5 grams of L-arginine by mouth daily seems to improve sexual function in people with ED. Taking L-arginine with medications such as sildenafil and tadalafil might work better than taking either L-arginine or the medication alone.
  • High blood pressure. Taking L-arginine by mouth can reduce blood pressure in healthy people, people with high blood pressure, and people with slightly high blood pressure with or without diabetes.
  • A serious intestinal disease in premature infants (necrotizing enterocolitis or NEC). Adding L-arginine to formula seems to reduce the risk for this condition in premature infants.
  • Narrowing of blood vessels that causes poor blood flow to the limbs (peripheral arterial disease). Taking L-arginine by mouth or by IV for up to 8 weeks increases blood flow in people with this condition. But using it for up to 6 months does not help to improve walking speed or distance. IV products can only be given by a healthcare provider.
  • A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Taking L-arginine by IV can reduce blood pressure in patients with pre-eclampsia. L-arginine might also reduce the risk of pre-eclampsia in people who are at high risk for this condition. IV products can only be given by a healthcare provider. It's not clear if taking L-arginine by mouth helps.
  • High blood pressure during pregnancy. Taking L-arginine by IV can reduce blood pressure in pregnancy. It's unclear if taking L-arginine by mouth lowers blood pressure during pregnancy, but it might decrease the need to take blood pressure lowering drugs. IV products can only be given by a healthcare provider.

Possibly Ineffective for

  • Long-term kidney disease (chronic kidney disease or CKD). Taking L-arginine by mouth or by IV doesn't improve kidney function in most people with CKD.
  • High cholesterol. Taking L-arginine by mouth doesn't help to lower cholesterol levels.
  • Heart attack. Taking L-arginine by mouth doesn't seem to help prevent a heart attack. It also doesn't seem to help treat a heart attack after it occurs. In fact, there is concern that L-arginine might be harmful for people after a recent heart attack. Do not take L-arginine if you have had a recent heart attack.
  • Tuberculosis. Taking L-arginine by mouth along with standard treatment for tuberculosis does not seem to help improve symptoms or clear the infection.
  • Wound healing. Taking L-arginine by mouth does not seem to improve wound healing.

There is interest in using L-arginine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: L-arginine is possibly safe for most people when taken short-term. It can cause some side effects such as stomach pain, bloating, diarrhea, and low blood pressure.

When applied to the skin: L-arginine is possibly safe for most people when used short-term. It's also possibly safe when used in a toothpaste short-term.

When inhaled: L-arginine is possibly safe for most people when used short-term.

Special Precautions and Warnings

When taken by mouth: L-arginine is possibly safe for most people when taken short-term. It can cause some side effects such as stomach pain, bloating, diarrhea, and low blood pressure.

When applied to the skin: L-arginine is possibly safe for most people when used short-term. It's also possibly safe when used in a toothpaste short-term.

When inhaled: L-arginine is possibly safe for most people when used short-term.

Pregnancy: L-arginine is possibly safe when taken by mouth for a short time during pregnancy. Not enough is known about using L-arginine long-term in pregnancy. Stay on the safe side and avoid long-term use.

Breast-feeding: There isn't enough reliable information to know if L-arginine is safe to use when breast-feeing. Stay on the safe side and avoid use.

Children: L-arginine is possibly safe in children when taken by mouth, when used in a toothpaste, or when inhaled.

Guanidinoacetate methyltransferase deficiency (GAMT): People with this inherited condition are unable to convert arginine and other similar chemicals into creatine. To prevent complications from this condition, avoid L-arginine supplements.

Recent heart attack: L-arginine might increase the risk of death after a heart attack, especially in older people. If you have had a heart attack recently, don't take L-arginine.

Kidney disease: L-arginine has caused high potassium levels when used by people with kidney disease. In some cases, this has resulted in a dangerous irregular heartbeat.

Surgery: L-arginine might interfere with blood pressure control during and after surgery. Stop taking L-arginine at least 2 weeks before a scheduled surgery.

Interactions

    Moderate Interaction

    Be cautious with this combination

  • Medications for high blood pressure (Antihypertensive drugs) interacts with L-Arginine

    L-arginine might lower blood pressure. Taking L-arginine along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely.

  • Sildenafil (Viagra) interacts with L-Arginine

    Sildenafil can lower blood pressure. L-arginine can also lower blood pressure. There is a chance that taking sildenafil and L-arginine together might cause blood pressure to go too low. But most people seem to be fine when taking these products together.

  • Medications for high blood pressure (ACE inhibitors) interacts with L-Arginine

    L-arginine might lower blood pressure. Taking L-arginine along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely.

  • Medications for high blood pressure (Angiotensin receptor blockers (ARBs)) interacts with L-Arginine

    L-arginine might lower blood pressure. Taking L-arginine along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely.

  • Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with L-Arginine

    L-arginine might slow blood clotting. Taking L-arginine along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

  • Medications for diabetes (Antidiabetes drugs) interacts with L-Arginine

    L-arginine might lower blood sugar levels. Taking L-arginine along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.

  • Isoproterenol (Isuprel) interacts with L-Arginine

    L-arginine seems to decrease blood pressure. Isoproterenol is a drug that is used to lower blood pressure. Taking L-arginine along with isoproterenol might cause your blood pressure to go too low.

  • Water pills (Potassium-sparing diuretics) interacts with L-Arginine

    L-arginine might increase potassium levels in the body. Some "water pills" might also increase potassium in the body. Taking L-arginine along with some "water pills" might cause too much potassium to be in the body.

    Minor Interaction

    Be watchful with this combination

  • Testosterone interacts with L-Arginine

    L-arginine might increase testosterone levels. But it's not clear if this is a big concern. People taking testosterone should be cautious until more is known about this potential interaction.

Dosing

L-arginine has most often been used by adults in doses that vary from 1.5 to 24 grams by mouth daily, for up to 18 months. It's also sometimes used in gels and creams. Speak with a healthcare provider to find out what type of product or dose might be best for a specific condition.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is licensed from Therapeutic Research Center, LLC. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
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