Ingredient profile · line 3 of 3
What is the L-arginine HCl in Melonex capsules?
L-arginine HCl in Melonex is the third and smallest line of the 500 mg proprietary blend: the amino acid L-arginine held as a hydrochloride salt. The label order caps it at about 167 mg per capsule, or about 333 mg at the two-capsule limit, salt included. Arginine blood pressure trials used 4 to 24 g a day.
Written by the Melonex label deskUpdated
The ingredient01
What is L-arginine HCl?
L-arginine HCl is L-arginine, an amino acid, bound to hydrochloric acid as a salt. On the Melonex label it is printed as "L-Arginine HCL", the third of three names inside the 500 mg proprietary blend.
Arginine is a semiessential amino acid. Your body makes some, and plant and animal proteins supply the rest, so most people who eat enough protein get it from meals (Health Library, Arginine).
The HCl tag only names the salt partner. It is the same L-arginine molecule, formula C6H14N4O2, that sits in line 2 of the blend as the alpha-ketoglutarate form.
| Name on the label | L-Arginine HCL |
|---|---|
| What it is | L-arginine as its hydrochloride salt |
| Place on the label | Line 3 of 3 in the 500 mg proprietary blend |
| Amount per capsule | Not listed; line 3 of 3 in the 500 mg blend, so at most 167 mg per capsule |
| Amount used in research | About 4-24 g a day of L-arginine in blood pressure trials |
| Strength of evidence | Small blood pressure drops in pooled trials |
| How it is meant to work | A common, stable salt form of arginine |
| Main caution | Same cautions as other arginine; stomach upset and bloating at higher doses. |
Per capsule02
How much L-arginine HCl is in one Melonex capsule?
One Melonex capsule holds at most about 167 mg of L-arginine HCl. The label does not print the amount, so that figure is a ceiling worked out from the order of the blend, not a measured dose.
A proprietary blend must list its parts from most to least by weight, with only the total shown (21 CFR 101.36, blends). Three lines share 500 mg. The last one can never be larger than the other two, so it tops out at a third of the blend.
The label sets no floor. Line 3 could be close to 167 mg, or far less. Part of whatever is there is the HCl partner, so the arginine itself is lower than the line weight.
| Case | 1 capsule | 2 capsules (label maximum) |
|---|---|---|
| Most line 3 can hold | About 167 mg | About 333 mg |
| Even split of the blend | About 167 mg | About 333 mg |
| Lines 2 and 3 together (both arginine forms) | At most about 333 mg | At most about 667 mg |
| Lowest amount printed | Not published | Not published |
| Arginine used in blood pressure trials | 4,000 to 24,000 mg a day (Dong 2011, arginine meta-analysis) | |
The even split and the ceiling land on the same number for line 3. Any other split gives it less.
Salt form03
Why does Melonex use two forms of arginine?
Melonex lists arginine twice, as an alpha-ketoglutarate salt in line 2 and as a hydrochloride salt in line 3. The label gives no reason for the pairing, and neither does the sales page (Melonex sales page).
Both forms deliver the same amino acid once the salt partner splits away. The HCl version is a common, stable salt of arginine. The AKG version pairs arginine with alpha-ketoglutarate, which is often sold to gyms as AAKG.
No trial we found compared the two forms for blood pressure. The pooled trials used oral L-arginine in general (Dong 2011, arginine meta-analysis).
L-arginine AKG
Arginine bound to alpha-ketoglutarate dihydrate. At most about 250 mg a capsule. Read the AKG profile.
L-arginine HCl
Arginine bound as a hydrochloride. At most about 167 mg a capsule, and the smallest share by label order.
Research04
What did arginine trials find, and at what dose?
Arginine trials found a small drop in blood pressure at doses of grams a day. Eleven double-blind trials with 387 people used 4 to 24 g a day and saw readings fall by about 5.39/2.66 mm Hg against placebo (Dong 2011, arginine meta-analysis).
A 2019 review put the median trial dose at about 9 g a day (Khalaf 2019, arginine and citrulline). At two capsules, Melonex line 3 holds about a third of a gram at most. That is under a tenth of the lowest trial dose.
The Health Library rates claims that arginine helps angina or high blood pressure as unsubstantiated (Health Library, Arginine). No trial has tested Melonex or its blend.
- Studied form: oral L-arginine, not a named salt, in most pooled trials
- Studied amount: 4-24 g a day, often split through the day
- Melonex line 3: at most about 0.17 g a capsule, 0.33 g at two
- Oral citrulline raised blood arginine more than oral arginine did in a dosing study (Schwedhelm 2008, citrulline kinetics)
The full blend math sits on the Melonex dose check.
Melonex: from $49 a bottle60 capsules · 2, 3 or 6 bottles · free US shipping on 3 or 6 · 60-day guarantee
See packsCautions05
Who should not take L-arginine HCl without a doctor?
People who have had a heart attack should not take arginine without their cardiologist. The VINTAGE MI trial gave 9 g a day after a first heart attack and was stopped early: six patients died on arginine (8.6%), none on placebo (VINTAGE MI trial, JAMA 2006).
Anyone on blood pressure drugs, nitrates or sildenafil needs a doctor's view first, since arginine may push pressure too low on top of them (Mayo Clinic, L-arginine). The label also asks pregnant or nursing mothers, anyone under 18 and anyone with a known medical condition to ask a physician first.
Common side effects at higher doses include nausea, stomach pain, diarrhea and bloating (Mayo Clinic, L-arginine).
A capsule of amino acids is not a stand-in for any drug your doctor set. Take the bottle along to your next appointment so your doctor can check the label.
The whole list of reactions is on Melonex side effects.
Food06
Can you get L-arginine from food instead of capsules?
Yes, food is the main source of arginine for most people. It is found in both plant and animal proteins, and a diet with enough protein supplies it (Health Library, Arginine).
That point matters for scale. A capsule adds at most a few hundred milligrams of arginine salts. Protein foods add arginine at every meal without any label math.
Diet patterns with stronger evidence for blood pressure, such as DASH, look at the whole plate rather than one amino acid (NHLBI, DASH eating plan).
The other lines07
Where does L-arginine HCl fit in the full Melonex formula?
L-arginine HCl is the smallest of the three active lines. L-citrulline DL-malate leads the blend, L-arginine AKG comes second, and the capsule shell plus two processing aids complete the label.
Each line has its own profile with the same ceilings and sources. The overview of all six label lines is on the Melonex ingredients page, and the full printed label is under supplement facts.
FAQ08
L-arginine HCl questions
Is L-arginine HCl the same as L-arginine?
Yes, it is L-arginine held as a hydrochloride salt. The arginine part is the same molecule. The difference is the weight: part of each milligram on the line is the HCl partner, so the arginine inside is a little less than the line weight.
Why is L-arginine HCl listed last on the Melonex label?
It is listed last because it weighs the least of the three blend lines. Federal rules make a proprietary blend list its ingredients from most to least by weight (21 CFR 101.36, blends). That order is the only clue to its amount.
Could a Melonex capsule hold very little L-arginine HCl?
Yes, it could. The label order caps line 3 at about 167 mg but sets no lower limit. The blend could be weighted heavily toward citrulline malate, leaving only a small amount of the HCl form. The maker has not published the split.
Does L-arginine HCl upset the stomach?
It can at higher doses. Mayo Clinic lists nausea, abdominal pain, diarrhea and bloating among arginine side effects (Mayo Clinic, L-arginine). A Melonex capsule holds far less arginine than those studies used, but stop and call your doctor if your stomach reacts.
Can I take an extra arginine supplement with Melonex?
Ask your doctor or pharmacist before stacking arginine products. The Melonex label says not to exceed the recommended dose, and extra arginine adds to the same interactions with blood pressure drugs, nitrates and sildenafil (Mayo Clinic, L-arginine). We do not suggest adding doses.
Does arginine raise potassium levels?
It may. The Health Library warns that arginine may raise blood potassium, which can be dangerous, and that single amino acid supplements may strain the kidneys (Health Library, Arginine). People with kidney disease or on potassium-sparing diuretics should check with a doctor first.
Is the L-arginine HCl in Melonex plant-based?
The label does not say how the arginine was made or sourced. It only states that the product is made in the USA with globally sourced ingredients. The capsule shell is plant cellulose, not gelatin.
Who wrote this09
Written and reviewed by
Pages built from the label, the sales page and linked NIH, FDA, AHA, CDC, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by a USA authorized Melonex retailer, not by the manufacturer or the distributor. We earn money when you buy through our order links.
Keep reading
More about Melonex
USA authorized Melonex retailer
Ready to try Melonex?
Check your medicines first, then pick a pack. Three or six bottles ship free in the US and cost less per bottle, and the 60-day guarantee opens after 30 days of use.
- Secure checkout
- 60-day guarantee
- Ships from the U.S.
