L-citrulline benefits for males: ED and more

While research on the topic is quite limited, some studies suggest that L-citrulline can offer erectile dysfunction (ED) — and other — benefits for males. 

In the body, L-citrulline is converted into L-arginine, another amino acid. This helps boost nitric oxide production, which, in turn, improves blood flow — a key factor in getting and maintaining an erection. Because improved blood flow supports more than just sexual function, L-citrulline may also benefit other aspects of health.

Read on for a closer look at L-citrulline for ED and beyond, including how the amino acid works and what research says about its potential benefits for males. 

L-citrulline works by boosting nitric oxide in the body, which relaxes blood vessels and improves the blood flow to the penis required for an erection.

Nitric oxide is a gas that is naturally produced in the body and is key for erectile function. It helps to facilitate erections by signaling blood vessels to widen (a process called vasodilation) and smooth muscles in the penis to relax. Importantly, L-citrulline is converted into L-arginine, another amino acid, which, in turn, helps produce nitric oxide. 

By supporting nitric oxide production, L-citrulline may indirectly relax blood vessels and improve blood flow — a crucial component for achieving and maintaining an erection. (Friendly reminder: ED is commonly the result of problems with blood flow.) 

So, the thinking is that upping your intake of foods rich in L-citrulline or taking L-citrulline supplements can increase the amount of the amino acid in your body, which can then boost nitric oxide levels and blood flow to (hopefully) support erectile function. 

L-citrulline and L-arginine are sometimes combined in supplements because they are involved in similar pathways that help with blood flow and could benefit ED.

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There isn’t one standard recommended dosage of L-citrulline for ED, largely because there is a limited amount of scientific evidence. That said, in one study evaluating the effects of L-citrulline on ED, participants received 1.5 grams of L-citrulline orally per day. 

If you want to up your levels of L-citrulline, you have two options: Eating more foods that contain the amino acid or taking a supplement. 

Watermelon, for example, is considered one of the best food sources of L-citrulline. The only problem? Research suggests you need to eat quite a bit of it (2.2–3.3 pounds per day) to achieve the minimum effective dose of L-citrulline. 

An easier option to boost your L-citrulline levels is taking a supplement. Once you start taking a citrulline supplement, it’s natural to wonder how long it will take to work. 

There aren’t many scientific studies on citrulline for ED, so it’s hard to say, but in one study, men took citrulline for a month to experience its benefits. Though this study was small, men reported a significant increase in self-reported erection hardness and number of sexual intercourse encounters per month.

Additional clinical research is currently underway on L-citrulline for ED, so we should have more insights into the supplement's efficacy for ED in the near future. 

Enhances athletic performance 

While there are some conflicting results in available studies, some research has been done on L-citrulline’s effects on exercise based on the hypothesis that the amino acid may improve blood flow to the muscles. This, in turn, may enhance athletic performance in both high-intensity exercises and resistance training. 

Remember how L-citrulline supports nitric oxide production, causing blood vessels to relax? Researchers believe this may improve the delivery of blood and oxygen to muscles during exercise, leading to better athletic performance. Data is mixed, but some studies have found an improvement in athletic performance with L-citrulline supplementation.

Improves heart health 

As explained above, L-citrulline may increase nitric oxide production, which causes vasodilation and improved blood flow. 

In addition to benefiting erections, this effect can also help the heart by improving circulation and reducing blood pressure, thereby lowering the strain on the cardiovascular system and, hopefully, the risk of conditions such as hypertension (high blood pressure). 

According to a scientific review, short-term L-citrulline supplementation has been shown to be somewhat helpful in reducing blood pressure in adults with pre-hypertension and hypertension. By lowering blood pressure, L-citrulline may also prevent or reduce damage to blood vessels. 

But more long-term research is needed to conclusively determine this potential effect.

Reduces inflammation 

Prolonged high levels of inflammation can lead to a slew of health problems, including cardiovascular diseases, diabetes, arthritis, and other chronic conditions. Citrulline can help reduce certain markers of inflammation, which could mean it can have a long-term beneficial effect on numerous organ systems in the body. 

L-citrulline side effects (when paired with L-arginine) include:

• Nausea

• Vomiting

• Diarrhea

• Headache

• Flushing

• Numbness

While L-citrulline is generally well-tolerated on its own, some people do experience side effects from L-arginine, with which L-citrulline is often coupled.

Unlike prescription medications, supplements are not as regulated by the Food and Drug Administration (FDA). Meaning, they do not have to go through the same rigorous testing for safety and efficacy before hitting shelves. 

To try to make sure the citrulline supplement you are considering taking is safe, general advice is to consider ones that have been tested by an independent third party, such as NSF International or Informed Choice. This ensures the dosage indicated on the label is correct and there aren’t toxic ingredients.

Side effects for amino acid supplements, like L-citrulline, can be especially concerning to elderly individuals or those with medical conditions like diabetes and liver disease. 

Taking too much could cause an amino acid imbalance, which could negatively impact the liver and other organs, such as the kidneys. This is especially a risk when an amino acid like L-citrulline is taken at a high amount (more than 10 grams). So consider this your reminder to stick with the recommended dose. More does not equal better.

Since L-citrulline and L-arginine are both amino acids and work together, it can be easy to assume they work the same way — including for ED — but there are some distinct differences between the two. 

As previously explained, L-citrulline is converted into L-arginine, which produces nitric oxide and helps with blood flow. 

You may think that taking an L-arginine supplement is a shortcut and leads to producing nitric oxide quicker, but studies show that L-citrulline can work better than L- arginine because it’s more bioavailable and can get converted to L-arginine in multiple areas in the body. That said, both amino acids do play an important role in increasing blood flow and improving ED.

L-citrulline isn’t necessarily the best (or only) thing you can do if you have ED. Here are some examples of alternatives.

Prescription medications 

There are FDA-approved options based on scientific studies, including medications known as phosphodiesterase type 5 (PDE5) inhibitors. These drugs are subject to far more regulation than supplements. Viagra (sildenafil), Cialis (tadalafil), vardenafil, and Stendra (avanafil) are all examples of PDE5 inhibitors used for ED. 

These medications work in part by increasing blood flow to the penis — something they have in common with the way L-citrulline supplements are proposed to work, but there is far more scientific evidence supporting the effectiveness and safety of these prescription drugs for erectile function.  

You can also find certain PDE5 inhibitors in other non-pill formulations. One example is Ro Sparks, a 2-in-1 sublingual treatment that contains both sildenafil and tadalafil (the active ingredients in Viagra and Cialis, respectively) and dissolves under your tongue for fast-acting effects. 

Then there are Ro’s Daily Rise Gummies, which contain 7 mg of tadalafil in each fruit-flavored gummy. 

These last two options have not been specifically FDA-approved for the treatment of ED, but their active ingredients have been individually FDA-approved for ED treatment.

Herbal extracts and botanicals

There is some evidence showing that certain herbal remedies may improve ED, including:

• Red Korean ginseng: May increase nitric oxide production, leading to increased blood flow for better erections. 

• Maca: May lead to erectile function improvement in men with mild ED, and might even boost sexual desire, too.

• Horny goat weed: May act similarly to prescription ED medications by inhibiting phosphodiesterase type 5 (PDE-5) and leading to better penile blood flow. 

• Yohimbe: May increase blood flow and nerve activity, which can help improve erectile function. 

Remember, these do not have as much evidence behind them as prescription medications do. They may or may not work for you. While all of these supplements may come with side effects, yohimbe in particular can cause serious side effects, including elevated blood pressure and heart rate. 

You should always check with your healthcare provider before taking new supplements

Lifestyle changes

Maintaining a healthy diet, exercising regularly, getting enough sleep, and looking after your mental health have all been shown to help with ED. 

Additionally, you may want to nix bad habits. Smoking cigarettes is a known risk factor for ED. Research shows that quitting smoking improves erectile function. Additionally, heavy drinking can cause erection troubles, which people sometimes call “whiskey dick.” So,limiting alcohol intake can help, too. 

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If you are experiencing ED regularly, taking a citrulline supplement could help because it is theorized to improve blood flow. 

• Besides helping with ED, L-citrulline may offer additional benefits for males, including supporting heart health and athletic performance. 

• Keep in mind, though, that research on L-citrulline for ED and other potential perks is rather limited. So, more research is needed to truly determine its effects.

• Your best (and safest) bet is to consult a healthcare provider if you’re dealing with ED, as they can determine what might be causing your symptoms and help find a solution that’s a fit for you, which might include prescription medications like Viagra or Cialis.