L-arginine is an amino acid that may help promote blood flow, athletic performance, and wound healing, among other benefits. But taking L-arginine supplements may interact with certain medications.

L-arginine is an amino acid, which is a building block of protein.

It’s necessary for the production of nitric oxide, a signaling molecule that’s needed for a variety of bodily processes and functions, including blood flow regulation, mitochondrial function, and cellular communication.

Additionally, L-arginine acts as a precursor to other amino acids, including glutamate, proline, and creatine, and is essential for the health and functioning of your immune system.

L-arginine is produced in several ways. It can be synthesized from the amino acid citrulline through the breakdown of body proteins or obtained through dietary protein intake from foods like meat, poultry, dairy, nuts, fish, and soy products.

It’s also available as a supplement in various forms, such as powder, liquid, capsule, and tablet.

Because L-arginine has so many critical roles in your body, a deficiency in this amino acid can disrupt cellular and organ function and lead to serious adverse health outcomes.

Keep reading to learn more about the possible benefits, risks, and uses of L-arginine.

Research has shown that L-arginine may offer various potential benefits when used as a supplement.

L-arginine supplements help increase nitric oxide in the body, which improves blood flow and oxygenation to organs, muscles, and tissues. Nitric oxide is also necessary for the relaxation of the cells that make up blood vessels.

L-arginine may also help reduce inflammation and oxidative stress, as well as improve glucose metabolism and insulin sensitivity.

These effects may contribute to managing chronic conditions like:

Other possible benefits of L-arginine may include:

However, it’s important to note that research on the possible effects of L-arginine is limited and inconclusive. It may not be as effective for some conditions as many supplement companies claim.

More research is needed.

Short-term use of L-arginine is generally safe and well tolerated when taken in supplement form.

However, it may cause gastrointestinal side effects, including:

Even though L-arginine supplements have a strong safety profile, it’s best to limit or avoid taking them if:

  • you’re pregnant or nursing
  • have kidney disease, low blood pressure, or guanidinoacetate methyltransferase deficiency
  • have recently had a heart attack
  • are going to have surgery in 2 weeks or more

Consider speaking with a healthcare professional before taking L-arginine supplements. They could help you decide whether they are safe to take or suggest an alternative supplement.

Doses of L-arginine vary widely depending on what it’s being used to treat.

Research has found the following doses to be helpful in managing certain conditions, but it’s important to note there are no clinical guidelines available:

  • High blood pressure: 15 and 30 grams (g) per day for up to 90 days
  • Erectile dysfunction: 1.5 to 5 g
  • Preeclampsia: 1 to 16 g when administered orally or 15 to 30 g when administered intravenously

It’s important to speak with a healthcare professional before taking L-arginine supplements. Also, follow the dosage instructions on the label carefully.

Like other single amino acids, it’s recommended to take L-arginine between meals for maximum absorption.

Is it possible to overdose on L-arginine supplements?

Limited research has examined the possible toxic effects of taking high doses of L-arginine.

Although L-arginine supplements are generally considered safe, speak with a healthcare professional before taking them, especially if you:

  • have an underlying health condition
  • are taking medications
  • are pregnant or nursing

L-arginine may interact with certain medications, including:

  • Blood-pressure-lowering medications: enalapril (Vasotec), losartan (Cozaar), amlodipine (Norvasc), furosemide (Lasix), etc.
  • Erectile dysfunction medications: sildenafil citrate (Viagra), tadalafil (Cialis), etc.
  • Blood-thinning medications: clopidogrel (Plavix), enoxaparin (Lovenox), heparin, warfarin (Coumadin), etc.
  • Diabetes medications: insulin, pioglitazone (Actos), glipizide (Glucotrol), etc.
  • Medications that increase blood flow: nitroglycerin (Nitro-Dur, Nitro-Bid, Nitrostat), isosorbide (Sorbitrate, Imdur, Isordil), etc.
  • Diuretic medications: amiloride (Midamor), triamterene (Dyrenium), spironolactone (Aldactone), etc.

Additionally, L-arginine may interact with certain supplements and substances, including:

Keep L-arginine supplements in a cool, dry area. Avoid exposing the supplement to heat or moisture.

L-arginine supplementation is sometimes used in pregnancy under certain circumstances, such as preeclampsia or the risk of preeclampsia and intrauterine growth restriction (IUGR).

During pregnancy, the body’s need for L-arginine increases due to fetal development and placental growth.

But this increased need may not be met through diet alone for everyone who is pregnant, especially:

  • people with limited access to protein-rich foods
  • people who follow restrictive diets
  • people who experience severe nausea and vomiting during pregnancy

According to a 2025 review, some studies suggest that L-arginine supplements may improve pregnancy outcomes and fetal and maternal health in pregnant people from high- and low-resource areas.

However, while the authors noted that L-arginine supplementation during pregnancy may have promise, more research is needed to fully understand the link between them.

Supplements during pregnancy should always be approved and monitored by a healthcare professional. If you are pregnant and interested in taking supplemental L-arginine, speak with a doctor for advice.

Similarly, limited research has examined the effects of L-arginine supplementation in people who are nursing. As such, speak with a doctor before taking supplements if you are nursing.

After consumption, your gut and liver rapidly metabolize L-arginine before it has the chance to reach systemic circulation. For this reason, some people suggest that L-citrulline may be better for increasing arginine levels.

L-citrulline is a nonessential amino acid that’s a precursor to L-arginine. It’s converted into L-arginine through a series of enzymatic reactions that take place primarily in your kidneys.

Research shows that L-citrulline supplements can raise body levels of L-arginine. In fact, some older animal studies show that L-citrulline may be more effective at increasing arginine levels than L-arginine supplements.

Like L-arginine, taking L-citrulline supplements may also offer possible benefits, such as:

  • lowering blood pressure
  • managing erectile dysfunction when added to a medical treatment plan
  • improving athletic performance and muscle recovery

That said, it’s important to note that more research is needed to fully support and understand the possible benefits of taking L-citrulline and L-arginine supplements.

L-arginine is an amino acid that is a primary building block of protein in the body. It’s available in high protein foods like meat, fish, poultry, and soybeans, as well as supplements.

Some research suggests that L-arginine supplementation may provide possible benefits, such as managing blood pressure, glucose levels, and erectile dysfunction, and improving athletic performance.

That said, experts agree that more research is needed to fully understand the possible benefits of L-arginine.

Consider speaking with a doctor before trying L-arginine supplements.