Key takeaways

  • Certain supplements contain compounds that the body can use to make nitric oxide, but they don’t contain nitric oxide itself.
  • Nitric oxide is produced naturally by the human body and is one of the most important molecules for blood vessel health.
  • It can increase blood flow, reduce blood pressure, and may be beneficial for managing certain health conditions or improving exercise performance.

Supplements that increase nitric oxide in the body make up one of the most popular supplement categories today.

These supplements don’t contain nitric oxide itself. However, they contain compounds that your body can use to make nitric oxide and may provide certain benefits for health and exercise performance.

Though these supplements are generally safe when taken in appropriate amounts, it’s still best to talk with a doctor or registered dietitian before trying them.

Erectile dysfunction (ED) is the inability to get or maintain an erection firm enough for sex. Nitric oxide is needed for the muscles in the penis to relax, which allows chambers inside the penis to fill with blood so the penis becomes erect.

L-arginine, an amino acid, is converted into nitric oxide in the body. A 2019 research review and analysis of 10 trials found that doses of this amino acid ranging from 1,500 milligrams (mg) to 5,000 mg may be beneficial for people with mild to moderate ED.

Another 2020 study suggests that combining 2,500 mg of L-arginine with 5 mg of tadalafil (Cialis) may be more effective for ED than either treatment alone.

French maritime pine bark extract, which comes under the brand name Pycnogenol, may also be beneficial. Pycnogenol has antioxidant properties and plays a role in the conversion of L-arginine to nitric oxide in the body.

Most studies have evaluated the effects of Pycnogenol and L-arginine together, and the results suggest that the combination may help improve sexual function in people with mild to moderate ED.

One supplement or treatment alone may be less effective than a combination of treatments. It’s best to talk with a healthcare professional before trying a supplement together with another supplement or medical treatment.

Citrulline malate, a form of the amino acid L-citrulline, not only increases nitric oxide production but may also reduce muscle soreness after strenuous physical activity.

Citrulline malate increases nitric oxide production, which increases blood flow to active muscles. In turn, citrulline malate is thought to increase nutrient delivery and clear waste products like lactate that are related to muscle fatigue.

However, researchers have often noted mixed results. For example, in studies included in a 2020 research review, 8 grams (g) of citrulline reduced muscle soreness after bicep curl exercises, but not after leg extension exercises.

Another review and analysis of 13 studies showed that, while citrulline could reduce muscle soreness 24 hours and 48 hours after exercise, it did not improve muscle soreness 72 hours after exercise.

Therefore, the ability of citrulline malate to decrease muscle soreness may depend on the dose, exercise, and timing. More research on this is needed.

Nitric oxide plays a key role in blood pressure regulation, and some research suggests that a nitric oxide deficiency may occur early in the development of hypertension (high blood pressure).

High blood pressure occurs when the force of your blood pushing against the walls of your arteries is consistently too high. It is defined as one or both of the following:

  • systolic blood pressure (the top number in a blood pressure reading) above 130 millimeters of mercury (mmHg)
  • diastolic blood pressure (the bottom number in a reading) higher than 80 mmHg

A diet high in fruits and vegetables is associated with lower blood pressure, and certain compounds in these foods may play important roles by affecting nitric oxide levels.

Nitrate

Nitrate is a compound found in beetroot and dark leafy greens like spinach and arugula. When you consume nitrate, your body converts it to nitric oxide, which in turn causes blood vessels to relax and dilate, lowering blood pressure.

Studies suggest that dietary nitrate may help lower blood pressure in both healthy young adults and older adults with conditions like overweight or prehypertension (blood pressure levels slightly above the normal range).

Flavonoids

Found in almost all fruits and vegetables, flavonoids are compounds that have powerful antioxidant properties. A large 2024 study found that increased intake of flavonoids may reduce the risk of high blood pressure.

There may be a few explanations for these beneficial effects. Specific flavonoids called anthocyanins can increase nitric oxide production in the body, and overall, flavonoids can increase the bioavailability of nitric oxide, meaning the body can use more of it.

However, a few studies have turned up conflicting results on the potential benefits of flavonoids.

For instance, a 2019 review of 15 trials found that consumption of flavonoid-rich fruits had no significant effect on blood pressure levels in adults.

More research is needed to determine whether flavonoids may play a role in blood pressure levels and, if so, how much someone may need to consume to see beneficial effects.

Nitric oxide is involved in many cell processes, including vasodilation (the widening of the blood vessels). Wider blood vessels help increase the delivery of nutrients and oxygen to working muscles during exercise, thus enhancing exercise performance.

This has made nitric oxide supplements popular among athletes and recreational gym-goers.

These supplements often contain several ingredients that may help increase nitric oxide, such as nitrate or the amino acids L-arginine and L-citrulline.

However, much of the research is mixed. For example, a 2025 umbrella review of 20 systematic reviews and analyses notes that dietary nitrate supplementation may improve factors such as:

  • the time it takes to become exhausted during exercise
  • muscular endurance
  • peak power output (the maximum power a person can generate in a short-duration exercise)

However, the researchers did not find improvements in other performance outcomes, and they also note that not all of the evidence in the included studies was reliable due to methodology issues.

A 2020 research review also notes that some studies have found potential positive effects of L-citrulline and citrulline malate on exercise performance, but many of the studies evaluated these ingredients in combination with other compounds or amino acids, like L-arginine. Therefore, it’s difficult to determine exactly what effects L-citrulline or citrulline malate may have.

More studies are needed to understand how these individual supplements may affect exercise performance.

For healthy adults, nitric oxide supplements are generally considered safe when taken in appropriate amounts. However, people with certain conditions should talk with a healthcare professional before trying supplementation:

For example, if you have hypotension (low blood pressure), supplements containing ingredients related to nitric oxide production may reduce your blood pressure to an unsafe level.

Some of these supplements, like L-arginine, may also cause side effects like nausea and diarrhea.

Beetroot juice supplements can also turn your urine and stool a dark red color. This is a common but harmless side effect.

And, as with any supplement, nitric oxide supplements may interact with medications.

This isn’t a comprehensive list of potential safety concerns. Before taking any supplements to increase nitric oxide, talk with a doctor or registered dietitian.

Nitric oxide is a molecule that plays many important roles in human health.

Supplements that may increase nitric oxide production often contain ingredients like nitrate or amino acids like L-arginine. These ingredients may provide certain health benefits, such as lower blood pressure or improved sexual function.

However, anyone who wants to try a supplement to increase nitric oxide should talk with a doctor or registered dietitian first.