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Benefits, uses, dosage, side effects, alternatives, and more

Discover the comprehensive breakdown of L-arginine – a semi-essential amino acid. Dive into its health benefits, potential side effects, recommended dosages, and more. Your one-stop resource for everything about L-arginine.

This article is based on scientific evidence, written by experts, and fact-checked by experts.
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L-arginine: Benefits, dosage, side effects, and overview
Last updated on January 26, 2024, and last reviewed by an expert on October 17, 2023.

L-arginine may boost blood circulation, enhance athletic performance, and help with recovery during severe illnesses. However, there might be reactions when combined with some medications.

L-arginine: Benefits, dosage, side effects, and overview

This article dives into the advantages and applications of L-arginine supplements.

In this article

What’s L-arginine?

L-arginine is a type of amino acid. Think of amino acids as protein’s building blocks. They come in two types: essential, which we must get from food because our bodies can’t produce them, and nonessential, which our bodies can create.

L-arginine falls into a special category – it’s semi-essential. This means, under certain situations like during pregnancy, when you’re a baby, in severe illness, or after an injury, your body can’t produce enough, so you need it from your diet.

One of its main roles is making nitric oxide, which helps in various body functions like regulating blood flow, helping our cells produce energy, and allowing cells to communicate with each other.

It also paves the way for other amino acids, including glutamate, proline, and creatine. These are vital for our immune system to work properly. For instance, arginine is crucial for the growth of T-cells – a type of white blood cell that’s essential for our immune defenses.

If you don’t have enough L-arginine, it can mess with how your cells and organs work, which can lead to health issues.

Our bodies get L-arginine in a few ways: from another amino acid called citrulline, from breaking down the proteins we eat, or directly from foods we consume.

You’ll find it in protein-rich foods like meat, chicken, milk products, nuts, soy foods, and seafood. On average, we get about 4–6 grams of L-arginine from our diets daily.

To give you an idea, studies indicate that our everyday food contributes to about 25-30% of the total L-arginine in our bodies.

If you’re looking for more, you can also get L-arginine from supplements. They come in various forms like powders, liquids, capsules, and pills, and are easy to find in stores or online.

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Summary: L-arginine is a semi-essential amino acid important for producing nitric oxide, supporting immune function, and more. It can be found in foods like meat, poultry, and nuts, but can also be taken as a supplement.

Health benefits and uses of L-arginine

L-arginine supplements are favored by athletes, those with certain health issues, and individuals recovering from illness. While some claims about its benefits are backed by studies, others might be exaggerated.

L-arginine might boost sports performance

Some research suggests L-arginine supplements might boost athletic performance by increasing nitric oxide levels, which enhances blood flow to muscles.

For instance, a 2017 study involving 56 male soccer players revealed that taking 2 grams of L-arginine daily for 45 days improved their performance significantly compared to a placebo group. Another study with 9 male participants found that consuming a drink with 6 grams of L-arginine an hour before rigorous exercise led to higher nitric oxide levels and longer exercise duration. However, many other studies argue against L-arginine enhancing athletic prowess.

L-citrulline, related to L-arginine, might be a more effective choice for athletic enhancement.

L-arginine may control blood pressure

Those with elevated blood pressure might benefit from L-arginine supplements. L-arginine aids nitric oxide production, crucial for blood vessel relaxation and pressure control.

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A review in 2016, analyzing 7 studies, revealed that both oral and IV L-arginine supplements noticeably decreased systolic and diastolic blood pressure in hypertensive adults.

L-arginine brings support during severe illnesses

During illnesses or post-surgery, our body might need more arginine than it can produce. A shortage can lead to issues like reduced immune function and disrupted blood flow. Thus, arginine supplements are sometimes given in clinical settings to support recovery, especially for conditions like severe infections, burns, or after surgeries.

L-arginine might regulate blood sugar

L-arginine might assist those with diabetes by bettering glucose metabolism and enhancing insulin sensitivity. As nitric oxide is crucial for insulin activity, boosting its levels can help our cells use glucose more effectively. Some studies even suggest that prolonged L-arginine use might help prevent diabetes in susceptible individuals.

Other potential benefits

Some other potential benefits of L-arginine include:

While the list covers various potential benefits, L-arginine is also being researched for its impact on other health conditions, like obesity, heart ailments, cancer, PCOS, infertility, and anxiety. But conclusive evidence is still lacking in many areas.

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Many also believe L-arginine can ward off colds or aid in weight loss, but concrete scientific support is limited.

Summary: L-arginine is a supplement taken for various reasons, including athletic performance enhancement, blood pressure regulation, managing critical illnesses, and blood sugar control. While some studies show potential benefits, like improved exercise performance and reduced blood pressure, results are mixed and more research is needed to confirm its effectiveness for many conditions.

Understanding side effects and being cautious about L-arginine

Studies indicate that L-arginine, when consumed as a supplement, is usually safe and typically doesn’t cause any problems, even when used daily for over a year.

That said, some folks might experience issues like bloating, tummy pain, feeling nauseous, and diarrhea, particularly if they’re taking big doses, like 9 grams or more daily.

Interestingly, one study that lasted 90 days and included 142 people found that daily amounts up to 30 grams didn’t cause any problems. This hints that even if you take a lot of L-arginine, it’s probably okay for a short duration.

Even with its mostly safe track record, there are certain people who should steer clear of arginine supplements. If you have asthma, liver cirrhosis, kidney issues, low blood pressure, or a specific inherited condition affecting arginine processing called guanidinoacetate methyltransferase deficiency, it’s best to skip L-arginine because it might not agree with you.

Summary: L-arginine is generally safe to take as a supplement, but large doses over 9 grams a day can cause stomach issues. However, people with conditions like asthma, liver or kidney disease, or certain inherited disorders should avoid it.

L-arginine dosage and how to take it

The right amount of L-arginine to take can vary widely, based on what you’re hoping to achieve with it.

For instance, when researchers looked into how L-arginine impacts blood pressure, they tested doses between 6 to 30 grams daily over periods ranging from 2 to 24 weeks.

For those dealing with erectile dysfunction, some studies suggest that a daily intake of 1.5 to 5 grams of L-arginine can help alleviate the issues.

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If it’s being used for preeclampsia treatment, typically 3 to 4 grams is taken daily for up to 12 weeks, or until the baby is born, all while under a doctor’s watchful eye. In some cases, if a pregnant woman has high blood pressure, L-arginine might be given to her directly into her veins at a clinic.

While research and clinics sometimes use bigger doses, for everyday use, it’s wise to stay below 9 grams of L-arginine a day. This helps in dodging stomach-related issues like feeling queasy, diarrhea, or a bloated feeling.

A little tip: For the best results, take L-arginine between your meals. This ensures your body absorbs it the best way possible.

Summary: L-arginine dosages vary depending on the purpose: for blood pressure, it’s 6–30 grams daily for a few weeks; for erectile dysfunction, 1.5–5 grams daily; and for preeclampsia, 3–4 grams daily. To avoid side effects, it’s advised to take less than 9 grams daily and consume between meals for best absorption.

L-arginine overdose

While arginine is mostly seen as safe, even at high doses, there’s still a risk of taking an excessive amount. This can be particularly risky for kids. More details on this are discussed further in this article.

Possible interactions

L-arginine might not mix well with some medications. Here’s a list of potential interactions:

L-arginine might also interact with some supplements:

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Summary: L-arginine can interact with various medications, including those for blood pressure, erectile dysfunction, diabetes, and more. It can also interact with certain supplements that affect blood pressure, blood sugar, and blood clotting, as well as with xylitol, which can lower blood sugar.

How to store and handle L-arginine

Store your L-arginine supplements in a place that’s cool and dry. While room temperature (around 25°C) is ideal, they can handle brief moments up to 40°C. Just make sure they’re away from too much heat or dampness.

Using L-arginine during pregnancy and when nursing

L-arginine sometimes finds a role in pregnancy, particularly in cases like preeclampsia.

If a pregnant woman is given L-arginine supplements, it’s usually for a clear medical reason, and a healthcare expert will always oversee this. Examples of such reasons might be risks linked to preeclampsia or issues with how the baby grows inside the womb.

Some data is suggesting L-arginine might boost the health of both the baby and the mom-to-be, whether they’re in well-off or more challenging living situations.

Here’s the thing: Pregnancy makes the body crave more L-arginine because of the baby growing and the placenta forming. Sometimes, especially for women in areas where nutritious food is hard to get, the diet might not satisfy this need. So, some women might require protein or amino acid supplements to meet the demand.

These supplements might also help women who are on very specific diets or who are dealing with intense morning sickness and can’t get enough nutrients from their food.

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Still, if you’re pregnant, don’t start taking any supplements without a nod from your healthcare provider. If you’re considering L-arginine, have a chat with them.

Regarding nursing moms, there’s not much research on L-arginine for them. So, if you’re breastfeeding, check with your healthcare professional before taking any L-arginine supplements. They’ll guide you on what’s best.

Summary: L-arginine is sometimes prescribed during pregnancy for specific conditions like preeclampsia, as it may improve pregnancy and health outcomes. If you’re pregnant or breastfeeding, always consult a healthcare provider before taking L-arginine supplements.

L-arginine guidelines for specific populations

L-arginine has been shown to be safe for many, from pregnant women to senior citizens. However, those with kidney or liver issues should steer clear of it.

In a medical setting, children might be given L-arginine supplements, and they’re usually okay if the dose is right. But, it’s crucial that a healthcare expert oversees this.

Don’t give L-arginine to your child unless a healthcare professional advises it. There’s a good reason for this caution: if kids get too much L-arginine, they could face serious health problems, even life-threatening ones.

Summary: L-arginine is safe for many, including pregnant women and older adults, but those with liver or kidney issues should avoid it. Always consult a healthcare provider before giving L-arginine to children, as incorrect dosing can be very harmful.

L-arginine alternatives

When you consume L-arginine, your digestive system and liver quickly process it, which means not much reaches your bloodstream. That’s why some suggest L-citrulline, which turns into L-arginine in the body, might be a more effective way to boost arginine levels.

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L-citrulline is an amino acid that can be taken as a supplement alternative to L-arginine.

This amino acid, L-citrulline, transforms into L-arginine, thanks to certain reactions primarily happening in your kidneys.

Studies indicate that L-citrulline can effectively increase L-arginine levels in the body, even more so than taking L-arginine supplements directly.

Benefits of L-citrulline seem to mirror those of L-arginine. For instance, both can help lower blood pressure and have shown potential in aiding with erectile dysfunction.

There’s also evidence that L-citrulline, either by itself or with L-arginine, can boost athletic performance and aid muscle recovery. Some research even suggests that L-citrulline might outperform L-arginine in enhancing athletic abilities.

So, for athletes looking to maximize performance, L-citrulline or a mix of both amino acids might be more beneficial than just L-arginine.

Summary: L-citrulline is an amino acid that can increase L-arginine levels in the body more effectively than taking L-arginine directly. This might offer similar health benefits like reduced blood pressure and improved athletic performance, making it potentially more beneficial for athletes than just L-arginine.


L-arginine is an amino acid found in foods like meat and nuts that can help boost the immune system and enhance athletic performance.

While it’s generally safe, taking more than 9 grams daily can cause stomach problems.

Certain individuals, like those with liver issues or asthma, should avoid it.

Overdosing can be especially harmful to children.

Always consult with a doctor before use, especially during pregnancy or when giving to kids.

Store it in a cool, dry place.

Another amino acid, L-citrulline, might boost L-arginine levels in the body more effectively.

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