Drug & supplement interaction

L-arginine + Diltiazem

Diltiazem brand names: Cardizem, Cardizem SR, Diltiaz SR, Cardizem CD, Tiazac, and others.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

L-arginine has a moderate interaction with Diltiazem. Theoretically, concomitant use of L-arginine and antihypertensive drugs may increase the risk of hypotension.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

L-arginine and Diltiazem

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Diltiazem

Diltiazem falls under ANTIHYPERTENSIVE DRUGS — the group L-arginine interacts with.

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.
Severity Moderate Likelihood Probable Evidence D

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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to keep in mind: diltiazem already works by relaxing your blood vessels so your heart doesn't have to push as hard. L-arginine can do something similar by boosting nitric oxide, which also widens blood vessels. Stack the two together and the blood-pressure-lowering effects may add up.

In real life, that could mean your blood pressure drops a little lower than expected. Watch for things like dizziness, lightheadedness (especially when standing up quickly), tiredness, or feeling flushed. This concern is theoretical, based on how both work rather than strong studies, so it isn't a reason to panic. Still, if you take diltiazem and are thinking about an L-arginine supplement, run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Siani A, Pagano E, Iacone R, et al. Blood pressure and metabolic changes during dietary L-arginine supplementation in humans. Am J Hypertens 2000;13:547-51. PubMed
  2. Cheng JW, Balwin SN. L-arginine in the management of cardiovascular diseases. Ann Pharmacother 2001;35:755-64. PubMed
  3. Huynh NT, Tayek JA. Oral arginine reduces systemic blood pressure in type 2 diabetes: its potential role in nitric oxide generation. J Am Coll Nutr 2002;21:422-7.. PubMed
  4. Higashi Y, Oshima T, Sasaki S, et. al. Angiotensin-converting enzyme inhibition, but not calcium antagonism, improves a response of the renal vasculature to L-arginine in patients with essential hypertension. Hypertension. 1998 Jul;32(1):16-24.
  5. Komers, R., Komersova, K., Kazdova, L., Ruzickova, J., and Pelikanova, T. Effect of ACE inhibition and angiotensin AT1 receptor blockade on renal and blood pressure response to L-arginine in humans. J Hypertens. 2000;18(1):51-59. PubMed
  6. Nagaya, N., Uematsu, M., Oya, H., Sato, N., Sakamaki, F., Kyotani, S., Ueno, K., Nakanishi, N., Yamagishi, M., and Miyatake, K. Short-term oral administration of L-arginine improves hemodynamics and exercise capacity in patients with precapillary pulmona
  7. Stokes, G. S., Barin, E. S., Gilfillan, K. L., and Kaesemeyer, W. H. Interactions of L-arginine, isosorbide mononitrate, and angiotensin II inhibitors on arterial pulse wave. Am J Hypertens. 2003;16(9 Pt 1):719-724.
  8. Palloshi, A., Fragasso, G., Piatti, P., Monti, L. D., Setola, E., Valsecchi, G., Galluccio, E., Chierchia, S. L., and Margonato, A. Effect of oral L-arginine on blood pressure and symptoms and endothelial function in patients with systemic hypertension,
  9. Ast, J., Jablecka, A., Bogdanski, P., Smolarek, I., Krauss, H., and Chmara, E. Evaluation of the antihypertensive effect of L-arginine supplementation in patients with mild hypertension assessed with ambulatory blood pressure monitoring. Med.Sci.Monit. 2
  10. Dong, J. Y., Qin, L. Q., Zhang, Z., Zhao, Y., Wang, J., Arigoni, F., and Zhang, W. Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials. Am.Heart J 2011;162(6):959-965. PubMed
  11. Dell'Omo, G., Catapano, G., Ebel, M., Gazzano, A., Ducci, M., Del, Chicca M., Clerico, A., and Pedrinelli, R. [Pressor, renal and endocrine effects of systemic infusion of L-arginine in hypertensive patients]. Ann.Ital Med.Int. 1995;10(2):107-112.
  12. Higashi, Y., Oshima, T., Ozono, R., Watanabe, M., Matsuura, H., and Kajiyama, G. Effects of L-arginine infusion on renal hemodynamics in patients with mild essential hypertension. Hypertension 1995;25(4 Pt 2):898-902.
  13. Li H, Liu Q, Zou Z, et al. L-arginine supplementation to mitigate cardiovascular effects of walking outside in the context of traffic-related air pollution in participants with elevated blood pressure: A randomized, double-blind, placebo-controlled trial. PubMed
  14. Shiraseb F, Asbaghi O, Bagheri R, Wong A, Figueroa A, Mirzaei K. The Effect of L-arginine Supplementation On Blood Pressure in Adults: A Systematic Review and Dose-response Meta-analysis of Randomized Clinical Trials. Adv Nutr 2021. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

L-arginine Also Interacts With Other Medications

L-arginine has 394 moderate, 8 minor known drug interactions in our database — the Diltiazem one above is one of them. If you take anything else, check it against the full list below.

Moderate 394 Minor 8 No known interaction 2,428 (incl. Diltiazem)
Taking anything else?

Check Another of Your Medications Against L-arginine

Covers the 2,830 medications we’ve checked against L-arginine. Pick one to open its full report.

From our Q&A

Questions About L-arginine or Diltiazem

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers L-arginine or Diltiazem, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Diltiazem

This page covers L-arginine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Diltiazem page lists 260 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Coleus (major) and Grapefruit (major).

By severity: 7 major · 214 moderate · 39 minor.

From our pharmacist’s overview on the Diltiazem page

“Someone on diltiazem (Cardizem, Tiazac) is usually managing blood pressure, angina, or a fast heart rhythm, so this list deserves genuine care. Seven of the 260 ingredients on file carry a major rating, and two of those are things people actually buy: grapefruit, which blocks the enzyme that clears diltiazem and can push its blood leve…”

Reviewed by 2 · Jul 18, 2026

Open the Diltiazem interaction page

One more smart check

Taking L-arginine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 26 real supplement products containing L-arginine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-arginine. Your product may carry other ingredients that interact with Diltiazem too, on top of L-arginine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where L-arginine and Diltiazem Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement L-arginine
Steady interest

#792 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Diltiazem
Top 10%

#282 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About L-arginine

What is L-arginine?

L-arginine
  • High blood pressure
  • Erectile dysfunction
  • Athletic performance
  • Chest pain (angina)
  • Improving blood flow

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.

Read the full L-arginine monograph & all interactions
Medication

About Diltiazem

What Is Diltiazem Used For?

Brand names: Cardizem, Cardizem SR, Diltiaz SR, Cardizem CD, Tiazac, Diltiaz XT, Diltiaz CD, Dilacor, Diltiaz, Cardizem LA, Dilacor XR, Cartia XT, Tiamate, Adizem-SR, Adizem-XL, Angitil SR, Angitil XL, Calcicard CR, Dilcardia SR, Dilzem SR, Dilzem XL, Slozem, Tildiem LA, Tildiem Retard, Viazem XL, Zemtard 120XL, Zemtard 180XL, Zemtard 240XL, Zemtard 300XL

Oral extended-release forms of diltiazem — including Matzim LA, Cardizem LA, Cartia, Cartia XT, Tiadylt ER, and various generic capsules and tablets — are used to treat high blood pressure (hypertension) and chronic stable angina (chest pain brought on by activity). Some capsule formulations, including Cartia, Cartia XT, and certain generics, are also approved for angina due to coronary artery spasm (sudden chest pain caused by a sudden tightening of a coronary artery).

Injectable forms of diltiazem are used in hospital settings to temporarily slow a dangerously fast heart rate in atrial fibrillation or atrial flutter (rapid, irregular heart rhythms), and to restore a normal heart rhythm in paroxysmal supraventricular tachycardia (PSVT) — sudden episodes of a very fast but regular heartbeat originating above the heart's lower chambers.

See full Diltiazem drug information
Keep checking

Other Drugs & L-arginine

Browse every other medication we’ve checked against L-arginine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
394Moderate
8Minor
2,427No known interaction
394 Moderate 8 Minor 2,427 No interaction
Moderate

394 interactions

Showing 60 of 394 moderate interactions — see all 394 on the L-arginine page.

Minor

8 interactions

No interaction 2,427 drugs checked — show the list

We also checked L-arginine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,427 medications checked with no known interaction — see the full L-arginine list.

See the full L-arginine interactions page
See every supplement checked against Diltiazem, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
L-arginine monograph › Uses, safety, and every drug interaction in one place Diltiazem supplement interactions › Every supplement checked against Diltiazem, ranked by severity Diltiazem drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking L-arginine and Diltiazem Together: Common Questions

Can you take L-arginine with Diltiazem?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the L-arginine and Diltiazem interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Diltiazem and L-arginine?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.