Is L-Arginine Safe?

To help avoid possible complications with L-arginine, safety concerns for the supplement should be discussed with a healthcare provider. For example, L-arginine can make some conditions worse, such as asthma, allergies, and herpes infections. To avoid these problems, tell your healthcare provider about all of your existing conditions before taking L-arginine. Safety precautions also apply to people who have low blood pressure or who have recently had a heart attack.

 

Is L-Arginine Safe?

L-arginine is an amino acid that is often used in dietary supplements. You should talk with your healthcare provider prior to taking L-arginine if you have:
 
Also, let your healthcare provider know if you are:
 
  • Pregnant or thinking of becoming pregnant
  • Breastfeeding.
     
Make sure to tell your healthcare provider about any other medications you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 

Specific L-Arginine Safety Warnings and Precautions

Some of the warnings and precautions to be aware of concerning the safety of L-arginine include the following:
 
  • L-arginine is a dietary supplement and is, therefore, not as closely regulated as prescription (or non-prescription) drugs. Also, it can be marketed without any proof that it is either safe or effective. Do not assume that just because it is sold in the United States, it is automatically safe or effective. Also, look for L-arginine from a reputable manufacturer. Your pharmacist is a good resource for information about which manufacturers are the most reputable. It is a good sign if a manufacturer abides by the rules of Good Manufacturing Practices (GMP) for drugs. It is also a good sign if a product has the United States Pharmacopoeia (USP) seal, which means that the product has been independently tested and shown to contain the correct ingredients in the amounts listed on the label.
     
  • L-arginine may cause a decrease in blood pressure. This could cause problems if you already have low blood pressure.
     
  • There have been reports that L-arginine can make allergies or asthma worse. If you have allergies or asthma, check with your healthcare provider before taking L-arginine.
     
  • Theoretically, L-arginine could aggravate a herpes infection (including genital herpes or cold sores).
     
  • Early research suggests that L-arginine could cause problems for people who have recently had a heart attack. In one study, taking L-arginine after a heart attack seemed to increase the risk of death.
     
  • L-arginine can interact with some medications (see L-Arginine Drug Interactions for more information).
     
  • It is not known if L-arginine supplements are safe for pregnant or breastfeeding women (see L-Arginine and Pregnancy and L-Arginine and Breastfeeding).
     
(Is L-Arginine Safe? Continued: Page 2)
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;