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How Long Does Citrulline Stay in the Body?


If you are suffering from issues such as poor blood flow, clotting, or other cardiovascular ailments, or if you’ve noticed you haven’t been pulling in the same gains from your workouts as you used to be able to, then the suggestion of taking L-Citrulline supplements might sound familiar.

But what exactly is L-Citrulline? Where does it come from? How does it affect the body, and how long do its effects last? 

Today, we are going to look at answering exactly those questions and more!


Key Takeaways

  • L-Citrulline is an amino acid that can be found in watermelon and synthesized by the body. It plays a role in improving cardiovascular health, promoting healthy blood flow, preventing clotting, and enhancing oxygen uptake throughout the body. It may also have benefits for athletes by improving aerobic performance.
  • L-Citrulline supplements can be taken based on personal goals and routines. Typical dosages range from 3,000 mg to 6,000 mg twice per day, with timing depending on individual needs. Effects can usually be noticed within a week of starting supplementation.
  • L-Citrulline is generally considered safe with minimal documented side effects. However, individuals with certain medical conditions, such as congenital heart disorders, chronic cardiovascular issues, diabetes, or those taking blood-thinning medication, should consult with a doctor before taking L-Citrulline. 


What is L-Citrulline?

In simple terms, L-Citrulline is a type of amino acid. As you might remember from your last biology lesson, amino acids are the fundamental building blocks of life and are incredibly important to every aspect of our physical health. 

You might also recall that amino acids can combine to form proteins. However, L-Citrulline is not one of those amino acids and plays a different role entirely within our bodies.

Most natural L-Citrulline is found in watermelon, though our bodies can also synthesize small amounts of it internally, provided our diet is in check.

L-arginine, a different kind of amino acid, is created when the body processes and metabolizes L-Citrulline. There is also Citrulline Malate, which is L-Citrulline blended together with malic acid, a combo that some claim leads to better absorption in the blood.

More on that down below!

What is Citrulline Good For?

Citrulline serves a few functions, but most of the hubbub surrounding this amino acid centers on its ability to improve cardiovascular health. Citrulline encourages strong, healthy blood flow and boosts oxygen uptake in nearly every part of the body.

It might even help prevent clotting, hypertension, and other common diseases connected to the heart, lungs, liver, and blood vessels.

Many men have also taken to using L-Citrulline supplements to remedy erectile dysfunction. On paper, it makes sense: anything that boosts blood flow is also likely to promote consistent, strong, and healthy erections.

In practice, citrulline is not as effective in this regard as drugs like Viagra or Cialis. However, L-Citrulline is much safer and largely free of side effects, which might be more important for some.

Athletes have also liked this amino acid because it can improve aerobic performance. By getting more oxygen to your muscles, it can allow you to last longer, giving you improved strength and stamina.


When to Take L-Citrulline

If you want to take L-Citrulline to augment and support your diet, then the optimal conditions for a daily citrulline supplement will depend on your routine, your needs, and the ultimate goals you are planning to achieve.

No official dosages for L-Citrulline exist, in common with most other dietary supplements. A typical amount would be between 3,000 mg and 6,000 mg twice per day. 

Usually, this means once in the morning, shortly after waking up, and once in the evening before bedtime. But if you are taking L-Citrulline to support your exercise goals, you’d be wise to structure your doses more closely around your workouts – one before and one just after.

It shouldn’t take more than a week for you to start noticing the effects of a citrulline supplement.


Is L-Citrulline Safe?

Compared to both over-the-counter and prescription drugs that offer similar effects, L-Citrulline is remarkably safe. Compared to most other supplements, citrulline is very well-researched, and no serious side effects have been documented thus far.

However, certain risk groups would be advised not to take citrulline supplements, or alternatively consult with their doctor before starting a citrulline-based program. They include people with congenital heart disorders, chronic cardiovascular issues, and the pregnant and elderly.

If you have diabetes or are on blood-thinning medication, you should also check in with your physician before taking L-Citrulline for the first time, just to be on the safe side.


Is L-Citrulline Vegan?

Yes, L-Citrulline is a natural compound found in many foods such as watermelon, squash, and others.

Some citrulline supplements are blended with different chemical ingredients to improve performance in some way, but it is very rare for these to be not vegan-friendly

To make sure, always check for appropriate and explicit labels on the packaging!


How Long Does Citrulline Stay in the Body?

Citrulline is metabolized relatively quickly, even at huge doses of 10 grams or more. In most cases, citrulline’s visible effects should wind down within a few hours, and it takes between 24 and 48 hours of being completely off L-Citrulline for it to be neutralized.


Can You Take L-Citrulline and L-Arginine Together?

Now, about the difference between L-Citrulline and L-Arginine that we mentioned earlier.

To reiterate: L-Arginine is a compound created due to the metabolic processes that make use of L-Citrulline in the body. Therefore, it really does not matter in practice whether you take L-Citrulline supplements or “ready-made” L-Arginine. 

As soon as you ingest either, they will be utilized by your metabolism in the form of L-Arginine anyway. That’s how it looks on paper, at least.

However, studies have hinted that L-Arginine is slightly less efficient at being absorbed into our system than L-Citrulline. Since citrulline is the amino acid naturally found in many fresh foods, this makes sense: our metabolism might have adapted better to converting citrulline to arginine rather than absorbing arginine directly.

As the research in this area is still weak and some reports differ, it would be best to discuss the benefits of each (or both) with your trusted physician.


Does L-Citrulline Break a Fast?

If you are fasting for health reasons and wondering whether taking L-Citrulline will throw your results off track, we have good news: L-Citrulline, in its natural form, does not contain any ingredients that would provoke an insulin response! 

However, some supplements might contain added sugars or other carbohydrates, so watch out when you’re shopping!


Our Favorite L-Citrulline Supplement Recommendations

If you want to take your health and workout performance up a notch, you’ll enjoy this roundup of some of the best Citrulline supplements we have listed below!

NOW Supplements

One of the best-value citrulline supplement makers out there, NOW Supplements, convinced us with their highly potent capsule-based supplements that manage to pack three months’ worth of daily doses into a tiny, colorful, and affordable package.

They do this using an extremely concentrated extraction process that allows for much smaller-than-usual capsule dimensions. Effectiveness is not compromised, though, and this also remains one of the stronger citrulline supplements we’ve tried.

There is one downside to this expert miniaturization and effective extraction: NOW Supplements do contain small amounts of calcium, up to 36 mg per serving.

For some purists and those on a fast or strict diet, this will be a dealbreaker, in which case we invite you to take a look at some of the other options further down the list. For the rest, though, this remains probably the single-best all-around option for an L-Citrulline supplement that works.

For self-proclaimed gymrats and workout freaks, BulkSupplements has the most heavy-hitting solution. Its L-Citrulline DL-Malate 2:1 supplement combines natural citrulline with malic acid, a blend that, as mentioned previously, has been shown to promote stronger results in terms of strength gain and physical endurance.

It might also provide a bigger “pump” than more conservatively-dosed citrulline supplements. At 3,000 mg per scoop of powder, this one isn’t for the faint of heart – but the results don’t lie!

For purists, BulkSupplements also offers a pure L-Citrulline powder, free of additives and flavorings. Everything from the packaging to the price point and overall feel and quality is remarkably similar. Even the dosage stays the same at a decidedly aggressive 3 grams. The only difference is the lack of additional malic acid.

The choice between these two will be one of personal preference – the benefits of malic acid in conjunction with citrulline have not been definitely proven yet, but some swear by it. Others will happily save a little bit of pocket change and go for the L-Citrulline powder instead.


For the finest balance between quality, value for money, and strength, look no further than Nutricost. Their Citrulline supplement comes in at 90 servings of 1,500 mg per box, sitting firmly in the midfield among similar supplements.

However, the brand’s extracts shine thanks to their class-leading purity and fineness. Nutricost chose not to augment their citrulline with any artificial additives. In other words, there are no additional flavorings, no sweeteners, no calcium, or any other minerals – just pure L-Citrulline.

For that alone, for providing a simple, no-nonsense, and incredibly well-made supplement at a comfortable price, Nutricost manages to earn a spot on our list of the best L-Citrulline supplements in 2022.


If you enjoyed this article, you might want to check out our article on the most powerful adaptogenic herbs!

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