L Arginine Side Effects List

L-Arginine can make asthma worse.

L-Arginine side effects are rare but they do occur. It is important to discuss L-Arginine with your health care provider before adding it to your diet.

Common L-Arginine Side Effects

L-Arginine is a natural substance found in food, and has no side effects when it is consumed. However, taking it in a supplemental form can cause problems in some people. Generally these side effects are not serious, ranging from mildly annoying to discomfort. In some instances, though, taking L-Arginine is dangerous and can be life threatening.

Side Effects of Oral L-Arginine

L-Arginine is most often taken orally. In this form common side effects include:

  • Nausea
  • Stomach pain
  • Bloating
  • Diarrhea
  • Gout

Side Effects of Injected L-Arginine

L-Arginine also causes some side effects when taken as an injection. These include:

  • Pain around the injection site
  • Low back pain
  • Flushing
  • Headache
  • Numbness
  • Onset of Restless Leg Syndrome

Side Effects of L-Arginine Intravenously

There are times when L-Arginine might be given to a patient in an I.V. Common side effects of L-Arginine when given in this form are:

  • Nausea
  • Vomiting
  • Headaches

L-Arginine Can Cause Some Serious Side Effects

While a very low percentage of side effects are serious they can occur. If you begin to have symptoms that seem to worsen, or concern you in any way, go to the emergency room immediately.

Serious Side Effects of Oral L-Arginine

If you experience any of these problems be sure to go to the emergency room to be checked. It is always better to be safe than sorry.

  • Breathing problems
  • Asthma becoming more intense
  • Allergic reactions including:
    • Rash
    • Hives
    • Itching
    • Unexplained swelling
    • Wheezing
    • Difficulty breathing
    • Difficulty swallowing

Serious Side Effects of Injected L-Arginine

When L-Arginine is injected it can cause:

  • Rapid drop in blood pressure
  • Changes in the chemicals and electrolytes in the blood
  • Death of the cells and tissue around the injection site
  • Nerve damage around the injection site

Serious Side Effects of Intravenous L-Arginine

  • Swelling of the face, especially in the eye area
  • Irritation to the veins and tissues surrounding the IV site
  • Damage to the vessels surrounding the IV site

Who Should Not Use L-Arginine?

In addition, there are people who just should not use L-Arginine. Side effects can be more pronounced in these patients and more severe.

After a Heart Attack

During preliminary research on the benefits of L-Arginine researchers found that a large number of patients given L-Arginine directly after a heart attack died. The patients that were not given L-Arginine did not die. This information was published in the Journal of the American Medical Association.

Patients on Blood Thinners

Patients who are taking blood thinners (anticoagulants like Coumadin) or anti-platelet medications should not take L-Arginine. L-Arginine increases circulation and may increase the risk of bleeding. Those with blood disorders like hemophilia should talk to their health care provider before using this supplement as well.


If you are on prescription medication to control blood sugar levels whether or not you are diabetic you should be aware that L-Arginine can increase your blood sugar levels dramatically. This can keep the medication from being able to control your blood sugar.

Others That Should Not Use L-Arginine

L-Arginine should not be used by those who fall in the following categories

  • Pregnant
  • Nursing mothers
  • Those with sickle cell anemia
  • Patients with liver disease

As more and more amino acids are studied and made available to the general public there is more potential for negative side effects. Often these side effects could have been avoided had the patient discussed his plans to take the supplement with his doctor. It is important that you do the research for yourself to find out if you have an underlying condition that could be negatively impacted by L-Arginine or any other nutritional supplement. Do not depend on the clerk at the health food store for your information but always research, read, and talk to your doctor.

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L Arginine Side Effects List