L-arginine
L-arginine
Supplements. Modern nutrition.
Also called Arginine, Arg, Arginine hydrochloride
Pinyin: jīng ān suān
Spanish: L-arginina
Can lower blood pressureAn amino acid the body uses to make nitric oxide, a gas that relaxes blood vessels, and it is sold mainly for sexual and heart health.
Did you know? Arginine was first isolated in 1886 from the seedlings of lupin, a plant in the pea family.
What it may help, and how strong the proof is
- Sexual health. Some small trials of men with erectile dysfunction used about 5 grams a day and found better erections. A small trial using 1.5 grams a day did not find a benefit.See the research: 32 studies in peoplePromising proof
- Heart health. Arginine helps make nitric oxide, which relaxes blood vessels. Small trials in heart disease are mixed. One small trial in people who had recently had a heart attack found more deaths with arginine, so they should avoid it.See the research: 771 studies in peopleTraditional proof
- Muscles & exercise. Many sports products add arginine for muscle pumps and performance. Trials in trained athletes have not shown a clear gain.See the research: 157 studies in peopleUnproven
Parts of the body
Traditional use
Arginine has no folk history. Its link to nitric oxide was found in the 1980s, and that discovery led to trials for blood vessel and sexual health.
How it is classified
- Herbal actions
- Nutritive, Circulatory. Energy: neutral.
How people take it
Erectile dysfunction studies have used up to about 5 grams a day. Ask a doctor before using higher amounts, especially if you have heart or blood pressure problems. Powders and capsules vary in strength, so check the label.
Capsule, powder and food.
Where to get it
The body makes some arginine, and food adds more. Good sources are meat, poultry, fish, dairy, nuts, seeds and soy. Powders and capsules are sold in health stores and online.
Be careful
Common side effects are stomach upset, bloating, diarrhea and nausea at higher doses, and arginine can lower blood pressure. Heart drugs, nitrates, sildenafil and tadalafil can add to that drop, and MedlinePlus warns it may raise the risk of death after a recent heart attack. Stop at least 2 weeks before planned surgery, since it can affect blood pressure control. Lab studies suggest arginine may help herpes viruses, so people with frequent cold sores may want to avoid high doses, and pregnancy and breastfeeding are not well studied.
Avoid if: recent heart attack; low blood pressure; frequent cold sores; pregnancy; kidney disease (ask a doctor); before surgery.
Mixing with other things
- Works well together
The body turns citrulline into arginine, and citrulline raises blood arginine more than arginine itself does. Some people take both.
- Use cautionBlood pressure medicine (lisinopril, amlodipine, losartan)
Arginine can lower blood pressure, which adds to blood pressure medicines.
- Use cautionHeart rhythm medicine (digoxin, amiodarone)
Heart drugs that lower blood pressure, including nitrates for chest pain, may add to the drop. Check with a doctor first.
Adds up with others that may lower blood pressure: , , , , , , , , , , , , , and 16 more.
The honest take
Arginine is a normal amino acid, and most people get enough from food. Small trials suggest a benefit for erectile dysfunction, but larger, longer trials are needed. Heart and athletic claims are not proven, and one trial after a heart attack found more deaths. The blood pressure drop also matters if you take heart or blood pressure medicines.
Sources
Each “See the research” link opens PubMed, the U.S. National Library of Medicine's index of medical studies, showing only trials and reviews done in people. The number tells you how much a use has been tested, not whether it worked. The proof rating tells you that.
Study counts checked October 2026.