Ingredient profile
L-Arginine HCl in Melonex: The Smallest Share, the Same Cautions
L-arginine HCl is the third ingredient in the Melonex blend, so one capsule holds at most 167 mg of it. It is the same amino acid as the second line, as a hydrochloride salt. Its cautions are the same: potassium-sparing diuretics, nitrates and a recent heart attack. No trial has tested Melonex.
Written by the Melonexcare editorsUpdated
No. 01What it is
What is L-arginine HCl?
L-arginine HCl is the amino acid arginine joined to hydrochloric acid, which turns it into a salt that dissolves easily and stays stable.
The label spells it "L-Arginine HCL" and lists it last in the blend. Once swallowed, the arginine is the same arginine as in the second line.
That means the research on arginine applies to both lines together. The HCl form adds no extra evidence, and the two forms are simply two sources of one amino acid.
| Name on the label | L-Arginine HCL |
|---|---|
| What it is | L-arginine as its hydrochloride salt |
| Place on the label | 3 of 3 in the 500 mg proprietary blend |
| Amount per capsule | Not listed; #3 of 3 in the 500 mg blend, so at most 167 mg per capsule |
| At the label maximum (2 capsules) | at most 333 mg |
| Amount used in research | 4-24 g a day of L-arginine in blood pressure trials |
| Strength of evidence | Same arginine research; the salt form adds no evidence |
| Role | Amino acid used to make nitric oxide |
| Main caution | Avoid with potassium-sparing diuretics (high potassium); bleeding risk with blood thinners. |
No. 02How much
How much arginine HCl is in a Melonex capsule?
At most 167 mg per capsule. Third place in a 500 mg blend cannot weigh more than a third of the blend, and the exact figure is not printed.
The label lists names from most to least by weight (21 CFR 101.36). If the third line were larger than 167 mg, it would outweigh the first or the second, and the order would be wrong.
It may be smaller. That is why we call it the smallest share. At two capsules a day, the ceiling is 333 mg of the salt.
No. 03Side effects
What are the side effects of L-arginine?
L-arginine side effects at large doses include stomach upset, nausea, abdominal pain, bloating and diarrhea. One capsule holds far less.
The NIH says arginine up to 9 g a day for weeks was well tolerated. At 9 to 30 g a day, stomach upset, diarrhea and nausea were common, and blood pressure was slightly lower (NIH ODS, arginine and citrulline).
A large clinic also lists headache, gout and worse asthma (Mayo Clinic, L-arginine). Safety beyond three months at high doses is not known (NIH ODS, arginine and citrulline).
A Melonex capsule is nowhere near those amounts, so these effects are unlikely from the capsule alone. Still, if you feel dizzy, sit down and tell your pharmacist.
No. 04Potassium
Is there a link between arginine and potassium?
Yes. Arginine may raise potassium in the blood, which matters if you take a potassium-sparing diuretic.
Mayo Clinic lists amiloride, spironolactone and triamterene as drugs to avoid with arginine, because potassium can climb too high (Mayo Clinic, L-arginine).
Those drugs already keep potassium in the body. The NIH adds that ACE inhibitors and ARBs can also push potassium up, especially with kidney problems (NIH ODS, Potassium).
Spironolactone patients are told to tell their doctor about potassium supplements and to avoid potassium salt substitutes (MedlinePlus, Spironolactone). If you take any of these, show your pharmacist the Melonex label first.
No. 05Medicines
Which medicines mix badly with L-arginine HCl?
Nitrates, sildenafil-type drugs, blood pressure medicines, blood thinners, diabetes drugs and potassium-sparing diuretics all call for a check first.
Mayo Clinic gives a short list (Mayo Clinic, L-arginine), and the reason sits beside each line.
| Medicine type | Concern |
|---|---|
| Nitrates, sildenafil | Pressure may drop too low |
| Blood pressure drugs | Pressure may drop too low |
| Blood thinners | Bleeding risk |
| Diabetes drugs | Blood sugar may drop |
| Potassium-sparing diuretics | Potassium may climb too high |
Never stop a medicine on your own. Ask first, and bring the bottle.
No. 06Heart attack
Should L-arginine be avoided after a heart attack?
Yes, unless your cardiologist says otherwise. One trial of arginine after a heart attack was stopped early for more deaths.
In VINTAGE MI, 6 people on arginine died (8.6 percent), against none on placebo (VINTAGE MI trial (ACC summary)). Mayo Clinic says arginine is not advised after a recent heart attack (Mayo Clinic, L-arginine).
Chest pain, fainting or shortness of breath means call 911. Do not wait to see if it passes.
No. 07Keep reading
Where should you read next?
The label's caution panel is shown above this profile. The other profiles cover the first two blend lines.
Read the arginine AKG profile for the studies on blood pressure, and the supplement facts for the full panel.
No. 08FAQ
L-arginine HCl questions
What is L-arginine HCl?
L-arginine HCl is the amino acid arginine joined to hydrochloride, a salt form. In Melonex it is listed third in a 500 mg blend, after citrulline malate and arginine alpha-ketoglutarate. It is the same arginine as the second line.
What are the side effects of L-arginine?
At large doses, stomach upset, nausea, bloating and diarrhea are the most common, with abdominal pain, headache, gout and worse asthma also reported (NIH ODS, arginine and citrulline) (Mayo Clinic, L-arginine). One Melonex capsule holds far less than those doses.
Can arginine raise potassium?
It can, in some people. Mayo Clinic says to avoid arginine with potassium-sparing diuretics such as amiloride, spironolactone and triamterene, since potassium may climb too high (Mayo Clinic, L-arginine). Ask your pharmacist before combining them.
How much L-arginine HCl is in Melonex?
The label does not say. As the third name in a 500 mg blend, it can be at most 167 mg per capsule, or 333 mg at two. The arginine itself weighs less than the salt.
Does Melonex have more arginine than citrulline?
That cannot be known. Citrulline malate is listed first, so it weighs the most, but two lines are forms of arginine, so the arginine total could be close to or above the citrulline total. The label gives no amounts.
Is L-arginine HCl safe with nitroglycerin or Viagra?
No, do not combine them without a doctor. Arginine with nitrates or sildenafil may drop blood pressure too low (Mayo Clinic, L-arginine). If you take either, ask your doctor or pharmacist before you use Melonex.
Can I take arginine with a blood thinner?
Ask first. Mayo Clinic lists blood thinners and antiplatelet drugs as an interaction, since bleeding risk may rise (Mayo Clinic, L-arginine). Your pharmacist can check your list.
No. 09Who wrote this
Written and reviewed by
Pages built from the bottle label, the seller’s order page and linked NIH, FDA, CDC, AHA, FTC and peer-reviewed sources.
Last updated . Learn about our editorial standards and how we check reviews. This website is run by Melonexcare, which describes itself as an authorized American Melonex outlet. It is not the manufacturer or the label’s distributor. Buying through our order links earns us money.
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