L-citrulline is a non-essential amino acid that plays a central role in nitric oxide production, blood flow enhancement, and athletic performance. Naturally found in watermelon, L-citrulline converts to L-arginine in the kidneys, which then boosts nitric oxide levels to support better circulation, stronger workout pumps, improved endurance, and cardiovascular health. Available in pure powder, capsule, and citrulline malate forms, it has become one of the most popular performance supplements on the market.
Quick Comparison
Product
Dose
Form
Best For
Rating
Iron Brothers Nitric Oxide with L-Citrulline
Multi-ingredient NO blend
Capsules
Best Overall
9.2/10
Natures Craft Nitric Oxide with L-Citrulline
Multi-ingredient NO blend
Capsules
Best Nitric Oxide Formula
9.0/10
Nutricost L-Citrulline
750mg per capsule
Capsules
Best Pure Capsule
8.9/10
NOW Foods L-Citrulline
1200mg per capsule
Capsules
Best Extra Strength
8.8/10
BulkSupplements L-Citrulline Powder
3000mg per scoop
Powder
Best Powder
8.7/10
L-Citrulline with French Pine Bark Extract
Citrulline + Pine Bark
Capsules
Best for Circulation
8.6/10
Double Wood L-Citrulline
1200mg per serving
Capsules
Best Budget Pick
8.5/10
1. Iron Brothers Nitric Oxide Supplement — Best Overall
Iron Brothers Nitric Oxide Supplement for Men & Women | Pre-Workout Nitric Oxide Booster for Enhanced Muscle Pump, Blood Flow & Endurance | L-Arginine, L-Citrulline, Pine Bark Extract | 120 Vegan Caps
Full, Energized Muscle Pump with Iron Brothers Nitric Oxide Supplement for Men & Women: Features a Quad-Action Nitric Oxide Formula with L-Arginine, L-Citrulline & Agmatine Sulfate to support a full muscle pump that lasts longer and doesn’t fade right away.
Support Healthy Blood Flow & Circulation: Our nitric oxide for women is formulated with Pine Bark Extract, Niacin & BioPerine, to support smooth circulation, efficient nutrient & oxygen delivery to active muscles – fueling your body during physical activity.
Boost & Sustain Your Nitric Oxide Levels with a Double-Lock Formula: This blend combines Niacin to support blood vessel dilation, maintain nitric oxide availability, and support sustained blood flow, endurance, and performance during intense workouts.
100% Caffeine-Free, Stimulant-Free Composition: Our pre-workout nitric oxide booster for men is designed to support clean workout energy & endurance without jitters or crashes. Ideal for late-day training or stacking with other performance supplements.
Vegan, Easy-To-Swallow Capsules with Maximum Absorption: What’s the point of a pump formula if your body can’t absorb it? Our nitric oxide capsules for men include black pepper extract to enhance nutrient uptake and absorb the key ingredients efficiently.
Iron Brothers delivers a comprehensive nitric oxide booster combining L-citrulline with L-arginine and supporting nutrients for maximum blood flow and pre-workout performance enhancement.
This pre-workout nitric oxide formula pairs L-citrulline with L-arginine and other performance-enhancing ingredients designed to maximize nitric oxide production and muscle pumps. The dual amino acid approach provides both immediate (L-arginine) and sustained (L-citrulline) nitric oxide elevation, giving athletes lasting performance throughout their workouts. Manufactured in a GMP-certified facility and suitable for both men and women.
Pros:
Dual L-citrulline and L-arginine formula for comprehensive NO support
Pre-workout nitric oxide booster designed for enhanced performance
GMP manufactured with quality testing
Cons:
Multi-ingredient formula makes it harder to dose citrulline precisely
Capsule format requires taking multiple pills per serving
Best for: Athletes and gym-goers who want a comprehensive nitric oxide supplement combining citrulline with arginine
2. Natures Craft Nitric Oxide with L-Citrulline — Best Nitric Oxide Formula
Natures Craft Energizing Nitric Oxide Supplement for Men – Nitric Oxide Pills for Men with L-Arginine L-Citrulline Amino Acids for Intense Muscle Growth Intense Energy and Smooth Recovery – 60 Count
Get those Gains – Our natural nitric oxide pre workout for men is powered by flavonoids and amino acids to increase nitric oxide levels and give you that ripped look
Natural formula – Unlike many other nitric oxide supplements for men our formula has no unnecessary additives to make space for extra L arginine and citrulline beet powder and AKG for real results
Amino acids supplement – Enhance your manly lifestyle with our muscle builder pre workout pills for better energy and size enlargement that won’t let you down in the gym or at home
Natural Energy – Just try our NO Rush preworkout energy pills and feel the Natures Craft difference in your daily exercise unlike so many other natural energy supplements for men
Natures Craft Quality – We are proud to be a leading name in natural mens health and muscle gainer bodybuilding supplements because we believe real results come from real ingredients you can trust
Natures Craft pairs L-citrulline with L-arginine and beetroot in a nitric oxide pill designed to support energy, circulation, and workout performance.
This energizing nitric oxide formula combines L-citrulline, L-arginine, and beetroot extract for a three-pronged approach to nitric oxide production. The beetroot provides natural dietary nitrates that directly convert to nitric oxide, complementing the amino acid pathway provided by citrulline and arginine. The capsules are easy to take before workouts or as a daily circulation supplement.
Pros:
Triple-action formula with citrulline, arginine, and beetroot
Supports both athletic performance and general circulation
Good value for a multi-ingredient nitric oxide supplement
Cons:
Individual ingredient doses lower than standalone supplements
Primarily marketed for men but suitable for all adults
Best for: Those who want a convenient all-in-one nitric oxide formula for daily energy and workout support
3. Nutricost L-Citrulline — Best Pure Capsule
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Nutricost offers pure L-citrulline in a straightforward capsule format with no added ingredients, providing 750mg per capsule for flexible dosing and exceptional value.
Each capsule contains 750mg of pure L-citrulline with no additional ingredients, fillers, or proprietary blends. The 180-capsule bottle provides a 2–3 month supply depending on dosing. Nutricost is known for transparent labeling, third-party testing, and GMP-compliant manufacturing. The product is non-GMO, gluten-free, and made in a FDA-registered facility in the USA.
Pros:
Pure L-citrulline with no added ingredients or proprietary blends
180 capsules provides excellent supply duration
Third-party tested with transparent labeling
Cons:
750mg per capsule requires multiple capsules for clinically studied doses
Capsule form limits dosing flexibility compared to powder
Best for: Users who want pure, standalone L-citrulline in capsule form without any additional ingredients
4. NOW Foods L-Citrulline 1200mg — Best Extra Strength
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NOW Foods delivers a potent 1200mg of L-citrulline per capsule — one of the highest single-capsule doses available — from one of the most trusted names in the supplement industry.
Each extra-strength capsule provides a full 1200mg of L-citrulline, reducing the number of capsules needed compared to standard 500–750mg products. NOW Foods maintains NPA A-rated GMP certification and has been a family-owned supplement company for over 50 years. The product is vegan, non-GMO, gluten-free, and dairy-free, making it suitable for a wide range of dietary needs. The packaging is designed to maintain freshness.
Pros:
High 1200mg per capsule reduces daily pill count
NPA A-rated GMP certification from a 50+ year brand
Vegan, non-GMO, gluten-free, and kosher certified
Cons:
Larger capsule size due to high per-capsule dose
Slightly higher price than budget alternatives
Best for: Those who want a high-dose single-capsule L-citrulline from a legacy supplement brand
5. BulkSupplements L-Citrulline Powder — Best Powder
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BulkSupplements provides pure, unflavored L-citrulline powder that allows for precise dosing and easy mixing into pre-workout shakes, smoothies, or water.
This 100% pure L-citrulline powder contains no additives, fillers, sugars, or artificial flavors. The unflavored formula makes it versatile for stacking with other supplements or mixing into any beverage. BulkSupplements is known for laboratory-tested purity and manufacturing in a cGMP facility. The powder format allows users to precisely dial in their preferred dose — from a moderate 2–3g daily to the clinically studied 6–8g pre-workout range.
Pros:
Pure, unflavored powder allows precise custom dosing
Easily mixes into pre-workout drinks, smoothies, or water
Excellent cost per serving — among the cheapest options available
Cons:
Requires a scale or measuring scoop for accurate dosing
Unflavored taste can be slightly sour or bitter
Best for: Athletes and fitness enthusiasts who want maximum dosing flexibility and the lowest cost per gram
6. L-Citrulline with French Pine Bark Extract — Best for Circulation
NatureU L-Citrulline Supplements, French Pine Bark Extract and L-Citrulline Complex, Nitric Oxide Supplement for Men, Performance Supplement for Men Health Endurance Recovery Support
Elevate Your Performance: Experience improved energy and overall vitality with the combined benefits of L-Citrulline and Pine Bark Extract, enhance circulation, supporting Men’s Health and helping you push your limits in workouts and daily activities
Maximize Nitric Oxide Production – Each tablet delivers a powerful 150mg of L-Citrulline and 60mg of French Pine Bark, designed to support nitric oxide levels for elevated physical performance
Support Energy, Muscle Growth & Recovery: Nitric oxide is important for relaxing and expanding blood vessels while you train. Supporting nitric oxide helps fuel nutrient delivery to working muscle tissue, creating an optimal anabolic environment for muscle building. The increased blood flow will enhance your pumps, strength, and endurance in the gym
One-Month Supply – With 30 tablets in each bottle, enjoy a convenient 1-month supply, making it easy to integrate this Citrulline supplements for men and Pine Bark Extract supplement into your daily routine for consistent support
Maximum Strength N.O. Stack – Look out! NatureU has unleashed a true powerhouse pre-workout formula packed with essential nitric oxide boosters; L-Citrulline. Nitric Charge delivers better value and better payoffs for your pump
This unique formula combines L-citrulline with French pine bark extract (Pycnogenol analog) for enhanced nitric oxide production and vascular health support beyond what citrulline alone provides.
French pine bark extract is rich in oligomeric proanthocyanidins (OPCs) that work synergistically with L-citrulline to support endothelial function and nitric oxide production. Clinical research on the combination of pine bark extract and L-citrulline has shown promising results for blood flow enhancement. This pairing makes it particularly relevant for cardiovascular health, circulation support, and those looking for performance benefits beyond pure pre-workout applications.
Pros:
Synergistic combination of L-citrulline and French pine bark extract
Targets vascular health and circulation beyond standard NO boosters
Research-backed ingredient pairing for enhanced nitric oxide support
Cons:
Niche product with fewer user reviews than mainstream options
May not provide sufficient citrulline dose for heavy pre-workout use
Best for: Those interested in L-citrulline for cardiovascular and circulation benefits rather than purely athletic performance
7. L-Arginine with L-Citrulline — Best Combination Capsule
L-Arginine Capsules with L-Citrulline – Nitric Oxide Supplement – L Arginine and L Citrulline Blend – 120 Count – Vegan, Non-GMO Capsules for Performance, Endurance and Muscle Support – 2 Month Supply
L-Arginine L-Citrulline Complex – Each serving contains a 1200mg blend of L-Arginine and L-Citrulline, ensuring maximum performance and muscle support during physical activities.
Supports Nitric Oxide Production – Our l arginine supplement for men and women helps support nitric oxide production, which may promote peak performance during exercise and support overall physical vitality.
Exercise Endurance – Fuel your active lifestyle with l-arginine for men and women, formulated to assist with endurance and recovery, helping you stay on top of your fitness goals.
Two-Month Supply – With 120 capsules per bottle, our L-Arginine and L-Citrulline supplement offers a convenient 2-month supply, providing long-term support for your fitness and wellness goals with ease.
Vegan & Non-GMO – Crafted with vegan and non-GMO ingredients, our L-Arginine capsules are produced to meet high standards, ensuring you get a reliable and hassle-free supplement for your active lifestyle.
This dual amino acid formula combines L-arginine and L-citrulline in a single capsule for comprehensive nitric oxide support that covers both immediate and sustained pathways.
Each serving provides both L-arginine and L-citrulline, the two primary amino acids involved in nitric oxide synthesis. L-arginine serves as the direct precursor to nitric oxide, while L-citrulline is recycled back into L-arginine in the kidneys, creating a sustained production loop. This combination approach provides a more complete nitric oxide strategy than either amino acid alone, making it suitable for both workout performance and daily cardiovascular support.
Pros:
Dual amino acid formula covers both immediate and sustained NO production
Versatile for both pre-workout and daily cardiovascular use
Clean capsule format with no artificial additives
Cons:
Individual doses of each amino acid are lower than standalone products
Capsule count may not last as long at higher serving sizes
Best for: Those who want both L-arginine and L-citrulline in a convenient single-product format
8. Doctor’s Best L-Citrulline Powder — Best for Cardiovascular Support
Doctors Best L-Citrulline Powder, Supports Circulatory Health, Non-GMO, Gluten Free, Soy Free, Vegan Net Wt. 7 oz (200 Grams)
Plays a crucial role in nitric oxide metabolism*
Helps alleviate muscle soreness*
Supports vascular health*
Non-GMO, Gluten Free, Soy Free, Vegan
Doctor’s Best delivers pharmaceutical-quality L-citrulline in an unflavored powder format specifically formulated to support circulatory health, nitric oxide production, and cardiovascular wellness.
Each scoop provides 3000mg of pure L-citrulline in an unflavored, easily mixable powder. Doctor’s Best is a physician-founded supplement company known for using well-researched, science-based ingredients. The product is non-GMO, gluten-free, soy-free, and vegan. The 200-gram container provides approximately 66 servings, making it a cost-effective option for daily cardiovascular and performance support.
Pros:
3000mg per serving hits an effective daily dose in a single scoop
Physician-founded brand known for science-based formulations
Unflavored powder mixes easily into any beverage
Cons:
Powder format may not be as convenient for travel
200g container is smaller than bulk powder options
Best for: Those who want a science-backed, pharmaceutical-quality L-citrulline powder for daily cardiovascular and performance support
How to Choose the Best L-Citrulline Supplement
The first decision is between pure L-citrulline and citrulline malate. Pure L-citrulline provides only the amino acid itself, while citrulline malate combines it with malic acid (typically in a 2:1 ratio) which may offer additional benefits for energy production during exercise. For general nitric oxide support and cardiovascular health, pure L-citrulline is ideal. For pre-workout performance and endurance, citrulline malate may provide slight additional benefits through its role in the Krebs cycle.
Dosage matters significantly with L-citrulline. Clinical studies showing performance benefits typically use 3–6g of pure L-citrulline or 6–8g of citrulline malate taken 30–60 minutes before exercise. For cardiovascular support and daily nitric oxide production, 2–3g daily may be sufficient. When comparing products, pay attention to whether the label lists L-citrulline or citrulline malate, as this affects the actual citrulline content.
Form is largely a matter of personal preference. Powder offers the most dosing flexibility and typically the lowest cost per gram, but requires mixing. Capsules are more convenient and portable but may require taking multiple pills to reach clinically effective doses. For those taking citrulline primarily as a pre-workout, powder mixed into a drink is the most common approach. For daily cardiovascular support, capsules are often more practical.
Third-party testing, GMP manufacturing, and clean ingredient labels are important regardless of form. Avoid products with unnecessary fillers, artificial colors, or proprietary blends that obscure actual citrulline content. The best products clearly state the amount of L-citrulline per serving and are backed by quality testing from independent laboratories.
Frequently Asked Questions
What is L-citrulline and what does it do?
L-citrulline is a non-essential amino acid naturally produced by the body and found in foods like watermelon, cucumbers, and legumes. Its primary function is boosting nitric oxide production — once consumed, L-citrulline travels to the kidneys where it converts to L-arginine, which then produces nitric oxide. Nitric oxide relaxes and widens blood vessels, improving blood flow throughout the body. This mechanism supports athletic performance (better muscle pumps, endurance, and recovery), cardiovascular health, and may even help with erectile function.
How much L-citrulline should I take daily?
For general health and cardiovascular support, 2–3g of L-citrulline daily is a common recommendation. For athletic performance and pre-workout use, research supports 3–6g of pure L-citrulline or 6–8g of citrulline malate taken 30–60 minutes before exercise. Start with 2–3g to assess tolerance and gradually increase. Splitting the dose between morning and pre-workout can also be effective for maintaining elevated nitric oxide levels throughout the day.
When is the best time to take L-citrulline?
For pre-workout performance benefits, take L-citrulline 30–60 minutes before exercise to allow time for conversion to L-arginine and nitric oxide production. For general cardiovascular support, taking it in the morning on an empty stomach can be effective. Some users split their daily dose between morning and pre-workout. L-citrulline does not contain stimulants, so it can be taken at any time of day without affecting sleep.
Are there any side effects of L-citrulline?
L-citrulline is generally considered very safe, even at higher doses. The most commonly reported side effects are mild digestive discomfort, including stomach upset or bloating, particularly when taken on an empty stomach at higher doses. These effects are typically temporary and resolve as the body adjusts. Rare side effects may include headaches or lightheadedness. Those taking blood pressure medications, PDE5 inhibitors (like sildenafil), or nitrate medications should consult a healthcare provider before supplementing, as the combined vasodilatory effects could cause excessive blood pressure reduction.
What’s the difference between L-citrulline and citrulline malate?
L-citrulline is the pure amino acid, while citrulline malate is L-citrulline bonded with malic acid, typically in a 2:1 ratio (meaning 6g of citrulline malate contains approximately 4g of actual citrulline and 2g of malic acid). Malic acid plays a role in the Krebs cycle and may offer additional benefits for energy production during exercise. Both forms effectively boost nitric oxide, but citrulline malate may provide slightly better endurance benefits due to the malic acid component. Pure L-citrulline delivers more citrulline per gram.
How long does it take for L-citrulline to work?
L-citrulline’s acute effects on blood flow and exercise performance can be felt within 30–60 minutes of ingestion, which is why it is commonly taken as a pre-workout supplement. Peak plasma citrulline levels occur approximately 1 hour after ingestion. For cardiovascular and chronic health benefits, consistent daily supplementation over 1–2 weeks is needed to see sustained improvements in blood pressure and vascular function. Research suggests that the full endurance and recovery benefits of L-citrulline supplementation become more pronounced after 7+ days of consistent use.