What Is L-Arginine? Health Benefits, Risks, and More
Diet & NutritionNutrients & Supplements

What Is L-Arginine? Potential Benefits, Known Risks, and More

What Is L-Arginine? Potential Benefits, Known Risks, and More
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Updated on November 4, 2025
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Note: The U.S. Food and Drug Administration (FDA) does not approve supplements for safety or effectiveness. Talk to a healthcare professional about whether a supplement is the right fit for your individual health, and about any potential drug interactions or safety concerns.

L-arginine is an amino acid that’s found naturally in certain protein-rich foods and is available as a supplement. It’s one of 20 amino acids your body uses to make crucial proteins for various essential functions.

 L-arginine helps dilate blood vessels, making it potentially helpful for lowering blood pressure, boosting sexual function, and improving exercise performance.

L-arginine is also found naturally in the body. “It’s considered a nonessential amino acid, which means your body can produce it on its own,” says Julia Long, RDN, a performance nutrition specialist in Houston.

Research on its effectiveness as a supplement is mixed, and your body typically makes enough of it for you. During periods of stress, your body may not produce the amount you need.

Potential Health Benefits of L-Arginine

L-arginine supplements may offer health benefits, but in most cases, the research is limited. Here’s a closer look at a few potential perks.

May Lower Blood Pressure

The body converts L-arginine into nitric oxide, a colorless, odorless gas that allows blood vessels to widen to increase blood flow. Because of that, some people take L-arginine supplements to possibly help improve hypertension.

Some research supports that idea. An Iranian systematic review and meta-analysis of 22 studies in people with and without high blood pressure found that supplementing with L-arginine was associated with a mean 6.4-point decrease in systolic blood pressure (the pressure caused by your heart contracting) and a 2.6-point decrease in diastolic blood pressure (the pressure in your arteries when your heart relaxes) compared with a placebo. But L-arginine, when taken for more than 24 weeks in trials did not show this significant decrease in blood pressure. Researchers concluded that studies on the long-term effects of L-arginine on blood pressure are needed.

On the other hand, not all medical professionals support supplementing with L-arginine for high blood pressure.

“The use of L-arginine for high blood pressure is controversial and not generally recommended,” says Anurag Sahu, MD, the director of the Adult Congenital Heart Center at Inova Health System in Fairfax, Virginia, and a medical reviewer for Everyday Health. “The data is limited, and the use of L-arginine in patients with a history of heart attack or kidney disease is generally contraindicated, since L-arginine can actually increase the risk for complications in these populations.”

Under the guidance of your doctor, dietary strategies, along with medication, will likely also be implemented to help lower blood pressure.

“With any case of hypertension, a low-sodium, higher-fiber diet containing healthy fat sources like avocado, salmon, and olive oil, should accompany any medication or supplement treatment to support heart health,” says Staci Gulbin, RDN, a health writer based in Denver.

May Boost Exercise Performance

L-arginine’s ability to improve blood flow may also help improve athletic performance. Wider blood vessels allow for the delivery of more oxygen and nutrients to muscles, which may prevent fatigue and help them work harder, explains Jenna Stangland, RDN, a board-certified specialist in sports dietetics in Minneapolis and the director of nutrition for the Minnesota Wild professional hockey team.

A review and meta-analysis conducted in Spain of 15 studies in athletes and healthy adults found that L-arginine supplements may improve both aerobic (physical activity that uses oxygen to create energy) and anaerobic (physical exercise that does not require oxygen to generate energy) exercise performance. Aerobic benefits included endurance, oxygen efficiency, and time to exhaustion, while the anaerobic benefits included increased power, reduced fatigue, and better recovery.

Based on those findings, the researchers suggested taking 1.5 grams (g) to 2 g of L-arginine daily for four to seven weeks to improve aerobic performance and 10 g to 12 g of L-arginine daily for eight weeks to improve anaerobic performance.

A recent Italian study also found that L-arginine taken with liposomal vitamin C may be helpful when added to inhaled therapy to improve symptoms and quality of life in those with chronic obstructive pulmonary disease (COPD), showing potential promise for a wider range of physical activity.

 Supplementing for COPD should only be done with a green light from your doctor, and these are newer results with more research needed.

May Improve Male Sexual Function

Some L-arginine supplements are marketed toward improving male sexual function, including erectile dysfunction (ED), which is the inability to achieve and maintain an erection. L-arginine may provide an assist by boosting blood flow to the penis.

A review and meta-analysis conducted in Korea of 10 randomized controlled trials concluded that supplementing with 1.5 g to 5 g of L-arginine — alone or with other ingredients in a combination supplement — significantly improved mild or moderate ED versus placebo or no treatment. It was also associated with more sexual satisfaction and orgasm.

The findings are echoed by a study conducted in China that shows combining L-arginine and Pycnogenol (maritime pine bark extract) may significantly improve sexual function in patients with mild to moderate ED.

“Given all the research on L-arginine currently available, I think this supplement may provide some benefit to those with mild to moderate ED,” says Gulbin.

But L-arginine supplements shouldn’t be used to self-treat ED. Gulbin recommends consulting with a board-certified physician to recommend more highly studied and effective treatments for your condition.

Weight Loss Effect of L-Arginine

L-arginine has both antioxidant and anti-inflammatory properties, which may assist with weight loss in people who are overweight or obese. Nitric oxide may also play a role in the synthesis and breakdown of fat, as well as the promotion of muscle gain.

But studies on the potential effects of L-arginine on body composition have mixed results. A meta-analysis of 12 trials in people with overweight or obesity, L-arginine supplementation was associated with a decrease in body mass index (BMI), body fat, and waist circumference, and an increase in lean body mass. On average, people lost more than six pounds of fat and reduced their waist circumference by more than one inch. Other studies found L-arginine supplementation had no effect on body weight.

Current evidence doesn’t show that L-arginine can be used as an effective tool for weight loss or weight maintenance on its own.

“Since L-arginine can increase your power and effectiveness while working out and promote muscle repair, it could help build muscle. But it wouldn’t affect your body composition if you aren’t working out,” says Long.

Adds Gulbin: “If you choose L-arginine, it should be used as only a secondary source of support for weight loss along with a healthy, balanced diet, regular physical activity, and adequate sleep patterns.”

Potential Risks and Side Effects of L-Arginine

Overall, L-arginine supplements are generally safe for healthy people.

 But there are some risks and side effects to keep in mind for those with certain health conditions.

Risks

L-arginine may interact with blood thinners, diuretics, nitroglycerin, and high blood pressure, ED, and diabetes medicines.

 If you’re taking any of these medicines or have these conditions, talk to your doctor about potential interactions.
It also may reactivate latent viruses in the body. Too much L-arginine in your system could cause cold sores and genital herpes to reappear, so don’t take L-arginine supplements if you have a history of these conditions.

You should also avoid L-arginine supplements if you have kidney disease; this amino acid may create an imbalance of electrolytes, which are minerals that regulate body fluids, and cause kidney complications. Those with gout should also be cautious and talk to their doctor before using L-arginine supplements.

 L-arginine may also increase the risk of death in people who have had a heart attack.

“Based on these risks, it is vital to consult with your healthcare provider first to be sure that it will not interact negatively with any health condition you may have or any medication you are prescribed,” says Gulbin.

Side Effects

Some research has found no major side effects from taking high doses (more than 9 g per day) of L-arginine

 but side effects that have been reported in other research include:

Stop L-arginine supplements and call your physician if you experience side effects.

Food Sources of L-Arginine

If you suspect you may benefit from consuming more L-arginine, Long recommends a food-first approach.

“Arginine is in so many food sources, many of which are heart-healthy,” she says. Instead of taking a supplement, focus on getting more oats, brown rice, nuts, legumes, turkey, eggs, and seeds in your diet.

L-arginine is also naturally found in seafood, soy protein, and watermelon.

How to Select and Store L-Arginine

Picking a safe and effective L-arginine supplement is important. It’s also essential to store the supplement properly to ensure the ingredients don’t break down.

Selection

While the U.S. Food and Drug Administration (FDA) doesn’t regulate supplements for safety or effectiveness before they’re sold, some independent organizations offer third-party testing to ensure the product was properly manufactured and contains the ingredients listed on the label. Look for a supplement that’s been third-party certified by organizations like USP, NSF, or ConsumerLabs.

Storage

In general, L-arginine should be stored in a cool, dry place. Read the label for specific instructions related to your product.

Dosage of L-Arginine

The dosages of L-arginine used in research varies widely. Studies suggest that L-arginine is safe in high doses (more than 9 g per day), while taking lower doses of 1.5 g to 3 g per day for more than four weeks may offer benefits for exercise performance.

The Takeaway

  • L-arginine is a naturally occurring amino acid found in protein-rich foods and is made by the body. You can also find it in supplement form. It supports blood vessel dilation, which may have a positive impact on blood pressure, exercise performance, and sexual function.
  • Findings about the possible benefits of L-arginine are mixed, and supplements should only be considered with a doctor’s approval, along with a healthy diet and treatments your doctor recommends for any existing medical conditions.
  • L-arginine may interact with certain medications, including heart and diabetes medications, as well as worsen existing kidney disease, and cause side effects such as bloating, diarrhea, or low blood pressure.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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