L Citrulline Blood Pressure: What the Trials Actually Show
L-citrulline shows up in almost every pump formula, and the search traffic around it has drifted from "better pumps" to "what does it do to blood pressure readings." That is a fair question, and the answer is more specific than a yes or a no.
Below is what randomized trials have measured in real people, how long those protocols ran, what happens when citrulline is paired with arginine, and who should talk with a clinician before using it.
If you are researching l citrulline blood pressure effects, the short answer is that a supplement is not a medication and the human data is narrower than the headlines suggest. L-citrulline is converted to L-arginine, and oral doses raise plasma citrulline, plasma arginine, and total nitrate and nitrite concentrations, the markers tied to nitric oxide production [1]. In a randomized placebo-controlled trial, 22 postmenopausal women took 10 g per day for 4 weeks, and the citrulline group showed smaller increases in aortic systolic pressure and pulse pressure during a handgrip stress protocol than placebo [2]. A 2022 meta-analysis of 884 randomized trials grouped L-citrulline among nutrients with moderate- to high-quality evidence for favorable effects on cardiovascular risk factors [3].
Those are group averages from research settings, usually at daily amounts far above what a capsule serving provides, and resting readings in healthy adults do not always move. The honest summary: L-citrulline supports nitric oxide production and healthy blood flow, and it may help support healthy blood pressure already in the normal range, but it is not a substitute for medical care, diet, or exercise [4].
What do the trials say about l citrulline and vascular pressure?
The mechanism is well mapped. Oral L-citrulline escapes much of the gut and liver breakdown that limits oral arginine, is converted to arginine in the kidneys, and increases plasma arginine along with nitrate and nitrite, the usual stand-ins for nitric oxide availability [1]. Nitric oxide signals the smooth muscle in vessel walls to relax, which is the pathway people have in mind when they ask about pressure readings [5].
The clearest human data
The most direct trial is small and specific. Twenty-two postmenopausal women were randomized to 10 g per day of L-citrulline or placebo for 4 weeks, and aortic measures were taken at rest, during isometric handgrip exercise, and during post-exercise muscle ischemia. The citrulline group showed attenuated increases in aortic systolic pressure, pulse pressure, and both forward and backward pressure waves during the ischemia phase compared with placebo [2].
Note what that trial measured: the size of the stress response, not a resting number, in one population that already has menopause-associated changes in arginine and endothelial signaling [6].
The bigger picture
A 2022 systematic review and meta-analysis covering 884 randomized trials and more than 880,000 participants placed L-citrulline and L-arginine among the supplements with moderate- to high-quality evidence for favorable effects on cardiovascular risk factors [3]. At the same time, reviewers of the exercise literature note that acute blood flow responses to citrulline are inconsistent across studies, so biomarker changes do not always translate into measurable hemodynamic shifts [1]. If you want the mechanism in more depth, see how L-citrulline works.
How fast did changes appear in the studies?
Two different clocks are running, and people mix them up.
The biochemical clock is fast. Research protocols that tested citrulline for exercise outcomes typically dosed within 2 hours before training, because plasma citrulline and arginine rise over that window [7]. Reviews of acute dosing confirm the rise in arginine and nitrate and nitrite markers after a single oral dose [1].
The vascular measurement clock is slower and less certain. The postmenopausal trial that found attenuated aortic pressure responses used 10 g per day for 4 weeks before retesting, so nothing in that design tells you what one dose does to a pressure reading [2]. Other citrulline protocols in athletes have run 6 g per day for 28 days, again measuring performance rather than hemodynamics [8].
So there is no reliable "it works in X minutes" answer for pressure readings, and claiming one would go past the data. Endurance performance results are a good reminder of the gap between mechanism and outcome: a meta-analysis of 118 studies found no benefit on endurance performance from citrulline-rich foods, even though nitrate-rich foods produced small benefits [9].
If you are tracking your own numbers, measure consistently, change one variable at a time, and share the readings with a healthcare professional rather than self-interpreting them [4].
What happens if you take L-arginine and L-citrulline together?
This combination is common in pre-workout formulas, including capsule products that list both. The rationale is that citrulline raises plasma arginine more efficiently than arginine itself, so pairing them targets the same nitric oxide pathway from two directions [1].
What the evidence supports
Both amino acids appear in the same meta-analysis grouping of nutrients with moderate- to high-quality evidence for favorable effects on cardiovascular risk factors [3]. Reviews of nitric oxide precursor supplementation describe arginine and citrulline as complementary substrates rather than redundant ones [5]. Co-ingestion studies with arginine and other ingredients have been reviewed, and the authors describe the combination research as preliminary rather than settled [1].
What it does not support
Taking both does not double anything. Strength outcomes with citrulline malate have not held up in meta-analysis: pooled data from resistance-trained adults found no overall effect on muscle strength [10]. Repetition performance findings are mixed across trials [11]. Where citrulline has shown more consistent results is perceived effort and soreness, with a meta-analysis of 13 randomized trials reporting reduced post-exercise rating of perceived exertion and muscle soreness [7].
Practically: stacking the two is reasonable from a mechanism standpoint and is how many formulas are built, but the combination has not been studied as a combination at the amounts found in most capsules. If you are weighing arginine on its own, the arginine evidence review covers it. Anyone on medication should clear a stacked nitric oxide product with a clinician first [4].
Is l citrulline safe, does it interact with medications, and who should skip it?
In the randomized trials reviewed to date, L-citrulline has generally been well tolerated at the amounts tested, with no pattern of serious adverse events reported in the exercise literature [1]. Tolerability was also not a limiting issue in the 4-week, 10 g per day protocol in postmenopausal women [2]. That is reassuring, but it is not the same as "safe for everyone in every situation."
Medication interactions
Because citrulline feeds the arginine and nitric oxide pathway, it is the wrong thing to add casually if you take any medication that acts on blood vessels or blood pressure. Dietary supplements can interact with prescription medicines and are not FDA-approved, so your pharmacist or prescriber should see the label before you start [4]. Do not adjust any prescribed medication because you added a supplement.
Who should be cautious
- Anyone taking blood pressure or cardiovascular medication, or any drug affecting circulation
- Anyone pregnant or nursing: arginine and citrulline in pregnancy are still an open research question, not an established use [12]
- Anyone under 18
- Anyone managing a diagnosed health condition or scheduled for surgery
If your pre-workout also contains caffeine
Many pre-workouts pair nitric oxide ingredients with stimulants. Caffeine has its own cardiovascular and sleep considerations, and high-caffeine products are a known concern for sensitive people [13]. People sensitive to caffeine, anyone pregnant or nursing, anyone under 18, and anyone training in the evening should limit or avoid caffeinated formulas. More detail is in our caffeine and blood pressure article. Talk with a healthcare professional before starting any supplement.
Where does citrulline fit in a pre-workout stack?
Citrulline earns its spot in pre-workout formulas for blood flow and training feel, not as a cardiovascular intervention. The ingredient supports nitric oxide production, and the most consistent randomized-trial outcome in healthy trainees is lower perceived exertion and less post-exercise soreness [7]. Strength gains are not a reliable outcome [10].
Surge is built around that pathway: it lists L-arginine (400 mg), L-arginine AKG (400 mg), L-citrulline as HCl (200 mg), citrulline malate (200 mg), beta-alanine (80 mg), and niacin (15 mg) per serving. The label serving is 2 capsules taken 20 to 30 minutes before training. Those amounts are a pre-workout formula, not the gram-level research protocols described above, and the product has not itself been studied.
It is made in the USA in an FDA-registered, GMP-certified facility and third-party tested for purity and potency.
A realistic way to use it
- Treat citrulline as a training-support ingredient that promotes blood flow during exercise, not as something aimed at a pressure reading [1]
- Keep the fundamentals in front: sleep, sodium and potassium from whole foods, regular aerobic work, and resistance training
- Track one change at a time so you can tell what is doing what
- Bring your supplement list to appointments [4]
If your goal is pumps and endurance during the session, Surge is the capsule format for that. If your goal involves blood pressure numbers, that conversation belongs with your clinician, not with a supplement label.
Frequently asked questions
How fast does l citrulline affect blood pressure?
There is no established time frame, and citrulline is not a medication. Plasma arginine and nitrate markers rise within about 2 hours of an oral dose, which is why exercise studies dose that close to training [7]. The trial that measured attenuated aortic pressure responses used 10 g per day for 4 weeks before retesting [2]. Discuss any blood pressure concern with a clinician.
Can l citrulline reduce blood pressure?
L-citrulline supports nitric oxide production and may help support healthy blood pressure already in the normal range, but it is not a substitute for medical care [1]. A 4-week trial in 22 postmenopausal women found smaller increases in aortic systolic and pulse pressure during a stress protocol versus placebo [2]. Broader meta-analysis evidence for cardiovascular risk factors is rated moderate to high but modest in size [3].
What happens if I take L-arginine and L-citrulline together?
They feed the same nitric oxide pathway, and citrulline raises plasma arginine more efficiently than arginine taken alone, which is why formulas often include both [1]. Both appear among nutrients with moderate- to high-quality evidence for cardiovascular risk factors [3]. Combination research is still preliminary, so do not assume additive effects, and clear stacked products with a clinician if you take medication [4].
Does L-citrulline interact with medications?
Possibly. Because citrulline supports the arginine and nitric oxide pathway, it should not be added casually alongside medications that act on blood vessels or blood pressure. Dietary supplements can interact with prescription medicines and are not FDA-approved, so show the full label to your pharmacist or prescriber before starting [4]. Never change a prescribed dose because you added a supplement.
Key takeaways
- L-citrulline raises plasma arginine and nitrate and nitrite markers, the pathway behind nitric oxide and blood flow [1].
- A randomized trial in 22 postmenopausal women using 10 g per day for 4 weeks found attenuated aortic systolic and pulse pressure responses during a stress protocol versus placebo [2].
- A meta-analysis of 884 randomized trials grouped L-citrulline among nutrients with moderate- to high-quality evidence for cardiovascular risk factors, with modest effect sizes [3].
- The most consistent outcome in healthy trainees is lower perceived exertion and less muscle soreness, not greater strength [7][10].
- Anyone on medication, pregnant or nursing, under 18, or managing a health condition should talk with a healthcare professional before starting citrulline [4].
If you want citrulline and arginine in a simple capsule you can take 20 to 30 minutes before training, take a look at Surge pre-workout capsules and read the full label before you decide.
References
- Effects of Citrulline Supplementation on Exercise Performance in Humans: A Review of the Current Literature. Journal of strength and conditioning research (2020). PubMed 31977835
- L-Citrulline supplementation attenuates aortic pressure and pressure waves during metaboreflex activation in postmenopausal women. The British journal of nutrition (2024). PubMed 37664994
- Micronutrient Supplementation to Reduce Cardiovascular Risk. Journal of the American College of Cardiology (2022). PubMed 36480969
- MedlinePlus: Dietary Supplements. medlineplus.gov
- Dietary supplements for improving nitric-oxide synthesis. Journal of preventive medicine and hygiene (2022). PubMed 36479475
- Cardiovascular Changes in Menopause. Current cardiology reviews (2021). PubMed 33155924
- Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis. Journal of sport and health science (2020). PubMed 33308806
- Effects of Combined Versus Single Supplementation of Creatine, Beta-Alanine, and L-Citrulline During Short Sprint Interval Training on Basketball Players' Performance: A Double-Blind Randomized Placebo-Controlled Trial. International journal of sports physiology and performance (2025). PubMed 40010353
- Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials. Journal of the International Society of Sports Nutrition (2021). PubMed 34965876
- Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Journal of dietary supplements (2022). PubMed 34176406
- Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis. International journal of sport nutrition and exercise metabolism (2021). PubMed 34010809
- Perspective: L-arginine and L-citrulline Supplementation in Pregnancy: A Potential Strategy to Improve Birth Outcomes in Low-Resource Settings. Advances in nutrition (Bethesda, Md.) (2019). PubMed 31075164
- NIH National Center for Complementary and Integrative Health: Energy Drinks. www.nccih.nih.gov
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational and educational purposes only and is not medical advice. Dietary supplements are not a substitute for a balanced diet, training, or sleep. Talk with a qualified healthcare professional before starting any supplement, especially if you are pregnant, nursing, under 18, taking medication, or managing a health condition.