Erectile Dysfunction and L-Citrulline: What You Should Know

Erectile dysfunction is one of the most concerning problems a man can have.

Most of us have had one episode or two, especially if we are under heavy stress. But having the same symptom frequently can break our self-confidence and self-esteem.

What can you do if you’re experiencing a dysfunctional sexuality?

In many cases, the cause is not purely biological but psychological in nature. However, there are plenty of medications and supplements we can use. One of them is L-Citrulline.

What is L-Citrulline?

L-citrulline is a natural amino acid. Its name originates from the Latin term of watermelon “Citrullus,” from which it was isolated for the first time. It is found in foods such as watermelons and naturally produced by the body.

L-citrulline is an amino acid that the body usually produces. It is useful for heart disease, bodybuilding, rising strength, and enhancing athletic performance in sportspeople.

There’s a subset of amino acids called non-essential amino acids. They are often called “the building blocks of life.” They are considered “necessary amino acids,” and must be provided by your diet. Others are produced by the body, and we know them as “non-essential amino acids.” If you don’t consume them in your diet, your body will create them for you.

L-citrulline has been called a “conditionally essential amino acid.” In theory, it is a non-essential amino acid. But according to research, there is a group of people whose levels of L-Citrulline are alarmingly low. In these individuals, usually critically ill patients, supplementation is considered “essential” (1).

The body transforms L-citrulline into another amino acid, L-arginine. L-arginine improves blood circulation. This improvement is achieved by stimulating nitric oxide production. It stimulates an enzyme called nitric oxide synthase. Nitric Oxide (NO) is a gas that promotes vascular dilation. Because of its artery-expanding effects, L-arginine benefits many types of patients. It is useful for heart problems, obstructed arteries, and erectile dysfunction.

Thus, a higher level of L-citrulline ultimately helps the body generate nitric oxide and increase the blood flow. It is sold as a dietary supplement and a separate pharmaceutical drug.

Sometimes you will find it as malate citrulline. This is simply citrulline bound to malate, an organic salt of malic acid. This is the most studied type of Citrulline, and there is evidence regarding an independent function of malate in performance effects.

Still, there is inadequate work to equate citrulline malate with L-citrulline specifically. It is important to note that 1,76 g of citrulline malate are required for an equivalent of 1 g of Citrulline.

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Why do people take L-Citrulline?

As stated above, L-citrulline increases the production of nitric oxide throughout the body. This helps to relax the smooth muscle and to improve different body functions. For example, people use it to improve lung function and enhance blood flow.

L-Citrulline may be useful in the diagnosis and prevention of diseases in the lungs and the circulatory system. Some evidence indicates that it can help lower blood pressure in prehypertensive individuals.

Prehypertensive individuals are those with early-notice hypertension. This means you have a blood pressure reading ranging from 120/80 to 139/89. This is considered slightly increased. In these cases, L-Citrulline is commonly used to counter the effects of prehypertension (2). 

Animal studies show that L-citrulline can also benefit people with diabetes-related issues in the blood vessels. For example, it is useful in patients with slow wound healing by stimulating nitric oxide and arginase systems (3).

Other animal work indicates that L-citrulline may stimulate muscle protein synthesis. It works to prevent muscle mass decay and muscle fatigue. Thus, it has been proposed to prevent older adults from frailty and critically ill people from cachexia. It is also useful to increase muscle strength (4).

Other lines of research also suggest that L-citrulline can help to treat intestinal issues. For example, Short bowel syndrome, Celiac disease, and Small bowel damage caused by radiation. Their consequences can be prevented with L-citrulline supplements (5). 

Many people can make use of citrulline supplementation. Endurance athletes and people who want to feel concentrated and alert without caffeine also consume L-citrulline.

In all of these cases, what it does is simply promoting vasodilatation (widening the blood vessels). By doing so, it increases the concentration of nutrients and oxygen to the muscles, the brain, and other tissues. It is very helpful to increase physical performance during your endurance training, too.

Can L-citrulline help erectile dysfunction?

L-citrulline supplements can alleviate symptoms of moderate to extreme erectile dysfunction (ED). Some scientists say L-citrulline doesn’t perform as well as ED medications like Viagra.

However, some people do not respond well to ED medications. Others do not have a serious condition and prefer not to use Viagra. For all of these patients, L-citrulline can be a useful alternative.

According to a study published in the medical journal Urology, oral citrulline supplementation is safe and effective in treating ED. It can improve erection hardness and works, especially if you have a mild case of ED (6).

We mentioned how L-citrulline stimulates the production of nitric oxide (NO). Then NO works in the penis as a vasodilator, but also as a neurotransmitter. Both functions are performed in the blood sinusoids. It creates a substance known as cGMP (or cyclic guanosine monophosphate).

In turn, this substance triggers smooth muscle relaxations in the penile sinusoids. This allows them to become filled with blood and compress the veins to prevent blood from scaping. Trapped blood in the penis is what causes an erection. We can achieve that by preventing cGMP breakdown (Viagra) or by increasing NO synthesis (L-citrulline) (7).

According to a more recent study published in the journal Andrology, a significant number of people with erectile dysfunction are likely to have a deficiency of L-citrulline. They evaluated 122 patients with different causes of erectile dysfunction. In each one of them, they evaluated the serum levels of arginine and citrulline.

After gathering and examining the data, they found out that many patients with ED have low arginine levels and low citrulline levels. This deficiency is more likely in patients with ED of an etiology related to arterial function (8).

However, arginine supplementation may not be ideal for ED. Arginine cannot escape liver metabolism.

The liver breaks down arginine before it starts performing actions on the penile tissue. Instead, citrulline escapes this presystemic metabolism. It gets converted into arginine and triggers NO synthesis. Hence the rationale to use L-citrulline instead of arginine for erectile dysfunction.

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How can you get L-citrulline in your diet?

L-citrulline is not an essential amino acid. But you can get plenty of it by finding the most appropriate sources. You can increase your dietary intake by consuming these L-citrulline rich foods:

  • Watermelon: It is one of the best citrulline sources. One research in eight men found that drinking 10 ounces (300 ml) of watermelon supplementation in the form of juice for over two weeks resulted in substantial changes in the bioavailability of nitric oxide (9). Thus, it is one of the most widely recommended natural sources of L-citrulline.

  • Garbanzo (chickpeas): Chickpeas are an excellent source of citrulline. They are also one of the best sources of protein in plants.

  • Peanuts: You can get your share of citrulline daily with peanuts, too. They contain a variety of vitamins and minerals, as well as fiber and healthy fats.

  • Salmon: This is one of the best-quality fishes you can find in terms of nutrients and health properties. It contains L-citrulline as well as healthy fats and other essential amino acids.

  • Liver: It might not be in your top 5 list of favorite foods, but the liver has high levels of citrulline, similar to red meat. However, we encourage you to eat moderately from these sources.

It is important to note that not all foods will contain enough citrulline levels to make a difference. If your symptoms of erectile dysfunction are recurrent, you may want to try supplements instead.

When to take L-citrulline supplements

Citrulline is usually added to pre-workout blends or taken early in the morning. To see the best results, you take them 30 minutes before exercise or after waking up. Many people like taking these supplements on an empty stomach to improve absorption.

Taking them in the morning can give you some extra energy and improve concentration. This may be especially effective if you take along Citrulline and caffeine. However, some people have replaced caffeine with citrulline supplements to get their morning boost.

To improve sexual activity, you need to take citrulline supplements continuously. It does not work like Viagra, which acts instantaneously. The benefits are rather seen in the medium-term, and you are required to continue supplementing to see the benefits.

How much Citrulline should you take?

The exact dosage of Citrulline you can take differs based on the type of Citrulline you’re consuming.

For example, if the supplement includes Citrulline Malate, you’ll want to have a higher dose. Remember that 1,76 g of citrulline malate are required for an equivalent of 1 g of L-Citrulline.

Your dose also depends on what you’re looking for. If you’re searching for general wellness advantages, you won’t need a high concentration. If you’re aiming for fitness-related benefits or improving erectile dysfunction, you will need a higher dose.

That said, a good starting dose of L-Citrulline is about three grams a day for general health. Increase the dose to three to five grams for better exercise performance and erectile dysfunction. As for Citrulline Malate, a good starting dose will be 5 to 6 grams for most people. But you can take up to 6 to 8 grams for better exercise performance.

Concerns and side effects

Significant side-effects are not documented. However, further work is required to validate its long-term safety in large doses. Unlike L-arginine and L-ornithine, large concentrations don’t appear to induce gastrointestinal distress (6).

As of yet, research to encourage the use of L-citrulline as a treatment for ED is minimal. The main focus of studies is placed on standard ED drugs such as Levitra, Viagra and Cialis. They are phosphodiesterase type 5 inhibitors and have proven to be very effective. 

However, some men prefer not to use them due to potential risks or side effects. This may be true, especially for men with mild ED. In such cases, it may be preferable to use L-citrulline, at least for short periods.

L-citrulline is thought to be healthy, as no known side effects have yet been observed in studies. However, no large, randomized clinical trial was conducted to assess the safety of L-citrulline for ED treatment.

Still, if you’re planning to take supplements or other drugs, you must talk about potential complications with your doctor. It is particularly important if you’re already using other medications to dilate your blood vessels. L-citrulline supplements may contain additional, similar synthetic ingredients to traditional ED medicines.

An important thing to note is that no alternative supplements can manage erectile dysfunction symptoms definitively. Also, one-third to half of the additives marketed as natural products contain synthetic chemicals. The most popular are PDE-5 inhibitors or PDE-5 inhibitors analogs, which are used in Viagra.

There is also concern that people who take nitrates for heart problems while taking these supplements may experience harmful drops in their blood pressure. So, it is essential that you still talk to your doctor before you start taking this or any other supplement.

Other natural remedies for ED

Not every patient who experiences ED may choose to use traditional prescription drugs. That’s why many alternative therapies and remedies still exist.

If you are searching for natural treatments to improve ED, one of these or a combination may be the one for you. Be sure to consult your doctor about natural remedies before you use one of these:

Penile air pumps

Penile pumps provide a non-invasive method for treating ED. They’re used to increase blood flow to the penis before sexual intercourse. This can cause swelling and pain if misused.

Penile implants

Implants can be inserted into the penis surgically, and then inflated before sexual intercourse.


Multiple peer-reviewed studies have shown that Panax ginseng is a safe, effective treatment for ED.


Dehydroepiandrosterone (DHEA) is a hormone produced by the adrenal glands of the body, naturally. However, though there are no recent reports, one older study found that people with ED often have low DHEA levels. Adding to those levels may also help to improve muscle strength in older adults. More up-to-date research is, however, needed (10).

RELATED: How to Increase DHEA Naturally in Men.


As we all know, this complementary medicine involves sticking needles into the upper layers of the skin. For decades, this procedure has been used to relieve discomfort, reduce health disorders, and treat various conditions.

One research in the International Journal of Impotence Research found that about a quarter of the men who received acupuncture enhanced erections and were able to perform sexually, compared to placebo (11).

When to see a doctor

  • If you have ED and would like to find a way to change your symptoms.

  • If you experience continuous episodes of ED, regardless of your age.

  • If you have been using Viagra irresponsibly and have become psychologically dependent on it to achieve hard erections.

  • If you’re having sexual dysfunction problems that affect your relationship or family life.

  • Speak to your doctor about other options if you don’t want to use sildenafil (Viagra) or tadalafil (Cialis), due to their possible side effects.

Many people hesitate to speak about these delicate things. But the sooner you ask for help, the sooner you will be able to find answers and the medical care you deserve.


L-citrulline is not an essential amino acid. However, some of us may have lower levels than others.

Low levels have been detected in patients with erectile dysfunction problems. They are especially low if the erectile dysfunction is caused by arterial problems. Supplementation with L-citrulline may be helpful in these cases.

What L-citrulline does is stimulating the synthesis of a substance called nitric oxide. In turn, nitric oxide expands the arteries by relaxing the smooth muscle. By doing so, it increases the blood flow to different tissues, including the penis. It facilitates penile erection and improves the hardness and maintenance of the erection.

We can find L-Citrulline in watermelon and other natural sources. They have been found to improve erectile dysfunction when consumed in sufficient amounts.

However, you can also supplement with L-citrulline. This supplement is associated with various health benefits besides improving erectile dysfunction. For example, it may reduce blood pressure readings and improve blood flow to the brain and muscles.

If you’re considering L-citrulline supplementation, it is important to talk to your doctor about it. Do not be afraid to talk about your concerns and find appropriate solutions according to your case.

Explore More


10 Natural Remedies To Improve Erectile Dysfunction In Men.


  1. Cynober, L. (2013). Citrulline: just a biomarker or a conditionally essential amino acid and a pharmaconutrient in critically ill patients?. Critical Care, 17(2), 122.
  2. Massa, N. M. L., Silva, A. S., Toscano, L. T., Silva, J. D. A. G. R., Persuhn, D. C., & Gonçalves, M. D. C. R. (2016). Watermelon extract reduces blood pressure but does not change sympathovagal balance in prehypertensive and hypertensive subjects. Blood pressure, 25(4), 244-248.
  3. Witte, M. B., Thornton, F. J., Tantry, U., & Barbul, A. (2002). L-Arginine supplementation enhances diabetic wound healing: involvement of the nitric oxide synthase and arginase pathways. Metabolism-Clinical and Experimental, 51(10), 1269-1273.
  4. Ham, D. J., Gleeson, B. G., Chee, A., Baum, D. M., Caldow, M. K., Lynch, G. S., & Koopman, R. (2015). L-Citrulline protects skeletal muscle cells from cachectic stimuli through an iNOS-dependent mechanism. PLoS One, 10(10), e0141572.
  5. Curis, E., Crenn, P., & Cynober, L. (2007). Citrulline and the gut. Current Opinion in Clinical Nutrition & Metabolic Care, 10(5), 620-626.
  6. Cormio, L., De Siati, M., Lorusso, F., Selvaggio, O., Mirabella, L., Sanguedolce, F., & Carrieri, G. (2011). Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction. Urology, 77(1), 119-122.
  7. Simonsen, U. L. F., Prieto, D., Delgado, J. A., Hernández, M., Resel, L., De Tejada, I. S., & García-Sacristán, A. (1997). Nitric oxide is involved in the inhibitory neurotransmission and endothelium-dependent relaxations of human small penile arteries. Clinical Science, 92(3), 269-275.
  8. Barassi, A., Corsi Romanelli, M. M., Pezzilli, R., Damele, C. A. L., Vaccalluzzo, L., Goi, G., … & Melzi d’Eril, G. V. (2017). Levels of l‐arginine and l‐citrulline in patients with erectile dysfunction of different etiology. Andrology, 5(2), 256-261.
  9. Bailey, S. J., Blackwell, J. R., Williams, E., Vanhatalo, A., Wylie, L. J., Winyard, P. G., & Jones, A. M. (2016). Two weeks of watermelon juice supplementation improves nitric oxide bioavailability but not endurance exercise performance in humans. Nitric Oxide, 59, 10-20.
  10. Morales, A., & Heaton, J. P. (2001). Horomonal erectile dysfunction: evaluation and management. Urologic Clinics of North America, 28(2), 279-288.
  11. Engelhardt, P. F., Daha, L. K., Zils, T., Simak, R., König, K., & Pflüger, H. (2003). Acupuncture in the treatment of psychogenic erectile dysfunction: first results of a prospective randomized placebo-controlled study. International journal of impotence research, 15(5), 343-346.

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