Herb & supplement monograph

L-arginine Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how L-arginine interacts with medications. The heart of this page is the interaction list — every drug L-arginine is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what L-arginine is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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L-arginine Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant L-arginine drug interaction appears low for most people, though a few medication groups deserve real attention. None of the listed interactions are rated major, and most reflect predicted additive effects rather than proven harm.

Interactions deserving the most attention

The best-supported concern involves blood pressure medications, including ACE inhibitors and ARBs, since human studies show L-arginine can lower blood pressure on its own and may add to these drugs' effects; ACE inhibitors and ARBs can also raise potassium, and L-arginine has been linked to high potassium in some patients. People taking diabetes medications should know L-arginine has lowered blood sugar in early research, which could add to their effect. There is also a theoretical bleeding concern with anticoagulant and antiplatelet drugs, since L-arginine may reduce platelet clumping, though its real-world significance is unclear.

What the rest of the list means

The long list of interacting medications does not mean each combination is harmful. Most entries are theoretical, based on the idea that L-arginine's effects on blood vessels, potassium, or blood sugar could add to a drug's action. In some cases, such as sildenafil, the predicted drop in blood pressure did not actually occur in studies of people using the two together.

Check your medications against L-arginine

Based on HelloPharmacist’s L-arginine interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with L-arginine

403 medications have a known interaction with L-arginine, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against L-arginine using our pharmacist-reviewed interaction data.

AI summaries are generated from our L-arginine interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact L-arginine combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs L-arginine affects

Every type of medication (drug category) L-arginine is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 9 drug categories L-arginine interacts with

Ace Inhibitors (aceis)Angiotensin Receptor Blockers (arbs)Anticoagulant/antiplatelet DrugsAntidiabetes DrugsAntihypertensive DrugsIsoproterenol (isuprel)Potassium-sparing DiureticsSildenafil (viagra)Testosterone

Ace Inhibitors (Aceis)

Theoretically, concomitant use of L-arginine and ACE inhibitors may increase the risk for hypotension and hyperkalemia.
Combining L-arginine with some antihypertensive drugs, especially ACE inhibitors, seems to have additive vasodilating and blood pressure-lowering effects. Furthermore, ACE inhibitors can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients. Theoretically, concomitant use of ACE inhibitors with L-arginine may increases the risk of hyperkalemia.

Likelihood Probable Evidence D

Angiotensin Receptor Blockers (Arbs)

Theoretically, concomitant use of L-arginine and ARBs may increase the risk of hypotension and hyperkalemia.
L-arginine increases nitric oxide, which causes vasodilation. Combining L-arginine with ARBs seems to increase L-arginine-induced vasodilation. Furthermore, ARBs can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients. Theoretically, concomitant use of ARBs with L-arginine may increases the risk of hyperkalemia.

Likelihood Probable Evidence D

Anticoagulant/Antiplatelet Drugs

Theoretically, concomitant use of L-arginine with anticoagulant and antiplatelet drugs might have additive effects and increase the risk of bleeding.
Preliminary research suggests that L-arginine infusions reduce platelet aggregation in humans. The clinical significance of this effect is unclear.

Likelihood Possible Evidence D

Antidiabetes Drugs

Theoretically, concomitant use of L-arginine might have additive effects with antidiabetes drugs.
Preliminary clinical research shows that L-arginine decreases blood glucose levels in patients with type 2 diabetes.

Likelihood Possible Evidence D

Antihypertensive Drugs

Theoretically, concomitant use of L-arginine and antihypertensive drugs may increase the risk of hypotension.
L-arginine increases nitric oxide, which causes vasodilation. Clinical evidence shows that L-arginine can reduce blood pressure in some individuals with hypertension. Furthermore, combining L-arginine with some antihypertensive drugs seems to have additive vasodilating and blood pressure-lowering effects.

Likelihood Probable Evidence D

Isoproterenol (Isuprel)

Theoretically, concurrent use of isoproterenol and L-arginine might result in additive effects and hypotension.
Preliminary clinical evidence suggests that L-arginine enhances isoproterenol-induced vasodilation in patients with essential hypertension or a family history of essential hypertension.

Likelihood Probable Evidence D

Potassium-Sparing Diuretics

Theoretically concomitant use of potassium-sparing diuretics with L-arginine may increases the risk of hyperkalemia.
Potassium-sparing diuretics can increase potassium levels. Use of L-arginine has been associated with hyperkalemia in some patients.

Likelihood Possible Evidence D

Sildenafil (Viagra)

Theoretically, concurrent use of sildenafil and L-arginine might increase the risk for hypotension.
In vivo, concurrent use of L-arginine and sildenafil has resulted in increased vasodilation. Theoretically, concurrent use might have additive vasodilatory and hypotensive effects. However, in studies evaluating the combined use of L-arginine and sildenafil for erectile dysfunction, hypotension was not reported.

Likelihood Possible Evidence D

Testosterone

Theoretically, concomitant use of L-arginine and testosterone might have additive effects.
In clinical research, L-arginine increases the level of testosterone in male patients with erectile dysfunction. The clinical significance of this finding is unclear.

Likelihood Possible Evidence D

Monograph

L-arginine: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

L-arginine is an amino acid that the body uses to make nitric oxide, a substance that helps blood vessels relax and widen. It is popularly used for blood pressure, erectile dysfunction, and exercise, but the evidence is mixed and stronger for some uses than others. It is generally well tolerated in healthy adults, but talk with a pharmacist or doctor before using it, especially if you have heart problems or take other medicines.

Part used: Amino acid (made by the body and found in protein-rich foods)
Common forms: Capsules, tablets, powders, sustained-release products

People commonly use it for

High blood pressure
Erectile dysfunction
Athletic performance
Chest pain (angina)
Improving blood flow

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Often well tolerated short-term, but it can lower blood pressure and may not be safe for everyone.

PregnancyPossibly Safe

When used orally and appropriately, short-term. L-arginine 12 grams daily for 2 days has been used with apparent safety in pregnancy during the third...

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

L-arginine is an amino acid, which is one of the building blocks the body uses to make proteins. Your body can make some L-arginine on its own, and you also get it from protein-rich foods like meat, poultry, fish, dairy, nuts, and beans.

Because it is a normal part of the diet, L-arginine is considered a "conditionally essential" amino acid. This means most people make enough, but during times of stress, illness, or rapid growth the body may need more than it can produce.

As a supplement, L-arginine is most often taken for heart and blood vessel health, erectile dysfunction, and exercise performance. It is sold as capsules, tablets, and powders, sometimes combined with other ingredients.

How it works

The main proposed mechanism is that the body converts L-arginine into nitric oxide, a molecule that signals blood vessels to relax and widen. Wider blood vessels can improve blood flow and may slightly lower blood pressure.

This nitric oxide pathway is the reason L-arginine is studied for conditions tied to blood flow, such as high blood pressure and erectile dysfunction.

L-arginine also plays roles in the body's handling of waste products (the urea cycle), wound healing, and immune function. Many of these effects are based on laboratory and animal research, and do not always translate into clear benefits in people.

Effectiveness

Does L-arginine work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 63 uses evaluated

6 Possibly effective 5 Leans ineffective 52 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Angina