Drug & supplement interaction

Barley + Diltiazem

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

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Barley and Diltiazem in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Barley and Diltiazem

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Diltiazem and Barley in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Barley safety at a glance

Barley overall Generally safe Barley is safe for most people when eaten as a normal food, but it contains gluten.
Pregnancy Likely Safe When used orally in amounts commonly found in foods. Read the full pregnancy detail
Breastfeeding Use caution Barley as a food is considered fine, but there is little safety data on concentrated barley supplements while breastfeeding.

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Diltiazem and Barley? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Diltiazem

Interactions in our licensed database are recorded against drug classes, not just single drug names. Diltiazem is filed under 9 classifications — including calcium channel blockers, cytochrome p450 1a2 (cyp1a2) inhibitors, cytochrome p450 3a4 (cyp3a4) inhibitors. Barley has documented interactions with 1 drug class — the most serious being triclabendazole (egaten) (moderate) — and none of Diltiazem’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Barley Does Interact With Other Medications

Barley has 1 moderate known drug interaction in our database — Diltiazem isn’t one of them. If you take anything else, check it against the full list below.

Moderate 1 No known interaction 2,829 (incl. Diltiazem)
Taking anything else?

Check Another of Your Medications Against Barley

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

What to actually watch for

No Interaction Found — But Data Suggests Barley and Diltiazem May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 4 of them are worth acting on rather than waiting out — marked below.

  • Shortness of breath / Fainting / Chest pain Worth acting on reported in 9.6% of FDA reports for Diltiazem Additional detail

    Barley

    “Orally, consumption of beer has been reported to cause allergic reactions in sensitive individuals. Symptoms included tingling in the face, lip, and tongue, angioedema, generalized urticaria, chest tightness, dyspnea, cough, fainting, and rhinoconjunctivitis. It can also cause anaphylaxis in sensitive individuals.”

    Barley · Natural Medicines adverse-effect record, reported in asthma.

    6 sources cited
    1. 33722. Curioni, A., Santucci, B., Cristaudo, A., Canistraci, C., Pietravalle, M., Simonato, B., and Giannattasio, M. Urticaria from beer: an immediate hypersensitivity reaction due to a 10- kDa protein derived from barley. Clin Exp Allergy 1999;29(3):407-413. PubMed
    2. 33724. Fernandez-Anaya, S., Crespo, J. F., Rodriguez, J. R., Daroca, P., Carmona, E., Herraez, L., and Lopez-Rubio, A. Beer anaphylaxis. J Allergy Clin Immunol. 1999;103(5 Pt 1):959-960.
    3. 317. Fernandez-Anaya S, Crespo JF, Rodriguez JR, et al. Beer anaphylaxis. J Allergy Clin Immunol 1999;103:959-60.
    4. 33762. van Ketel, W. G. Immediate type allergy to malt in beer. Contact Dermatitis 1980;6(4):297-298. PubMed
    5. 33735. Cronin, E. Contact dermatitis from barley dust. Contact Dermatitis 1979;5(3):196. PubMed
    6. 33770. Gutgesell, C. and Fuchs, T. Contact urticaria from beer. Contact Dermatitis 1995;33(6):436-437. PubMed

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Hives Worth acting on Additional detail

    Barley

    “Topically, barley malt contained in beer has been reported to cause contact dermatitis. After occupational exposure, barley has been reported to cause contact dermatitis of the eyelids and extremities, as well as contact urticaria.”

    Barley · Natural Medicines adverse-effect record, reported in dermatitis.

    4 sources cited
    1. 33762. van Ketel, W. G. Immediate type allergy to malt in beer. Contact Dermatitis 1980;6(4):297-298. PubMed
    2. 33735. Cronin, E. Contact dermatitis from barley dust. Contact Dermatitis 1979;5(3):196. PubMed
    3. 33770. Gutgesell, C. and Fuchs, T. Contact urticaria from beer. Contact Dermatitis 1995;33(6):436-437. PubMed
    4. 33774. Pereira, F., Rafael, M., and Lacerda, M. H. Contact dermatitis from barley. Contact Dermatitis 1998;39(5):261-262. PubMed

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

  • Bloating or gas Additional detail

    Barley

    “When consumed orally, barley provides fiber. Increasing fiber in the diet can cause flatulence, bloating, abdominal distention, and unpleasant taste. To minimize side effects, doses should be slowly titrated to the desired level. Adverse effects usually subside with continued use.

    Barley contains gluten.”

    Barley · Natural Medicines adverse-effect record, reported in flatulence.

    3 sources cited
    1. 12514. Lembo A, Camilleri M. Chronic constipation. N Engl J Med 2003;349:1360-8. . PubMed
    2. 33763. Ellis, H. J., Doyle, A. P., Day, P., Wieser, H., and Ciclitira, P. J. Demonstration of the presence of coeliac-activating gliadin-like epitopes in malted barley. Int Arch Allergy Immunol. 1994;104(3):308-310. PubMed
    3. 33772. Baker, P. G. and Read, A. E. Oats and barley toxicity in coeliac patients. Postgrad.Med J 1976;52(607):264-268. PubMed

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

  • Numbness or tingling / Cough Additional detail

    Barley

    Recorded for Barley in the same Natural Medicines adverse-effect record shown under Shortness of breath / Fainting / Chest pain above.

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

  • Stomach upset Additional detail

    Barley

    Recorded for Barley in the same Natural Medicines adverse-effect record shown under Bloating or gas above.

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

  • A skin rash Additional detail

    Barley

    Recorded for Barley in the same Natural Medicines adverse-effect record shown under Shortness of breath / Fainting / Chest pain above.

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

Reported for Barley but not commonly for Diltiazem: an allergic reaction, a severe allergic reaction and wheezing.

Effects for Diltiazem come from the ADVERSE REACTIONS section of its FDA label; effects for Barley come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 34,400 voluntary FDA FAERS reports for Diltiazem that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Barley in Pregnancy & Breastfeeding

Pregnancy Likely Safe

When used orally in amounts commonly found in foods.

Pregnancy Possibly Unsafe

When barley sprouts are consumed in relatively high doses. Excessive amounts of barley sprouts should not be consumed during pregnancy.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Diltiazem Is Prescribed For, and What Barley Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Diltiazem is a prescription medicine with approved uses on its FDA label. Barley is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Diltiazem is prescribed for: 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.

Barley has been studied for:

  • Hypertension studied, not established Barley has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Barley for hypertension

    Although there has been interest in using oral barley for hypertension, there is insufficient reliable information about the clinical effects of barley for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Diltiazem on your own; if you are taking Barley for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Barley 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 Barley 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 Barley 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 Barley as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2,448 real supplement products containing Barley, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Barley. Even though Barley itself has no known interaction with Diltiazem, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Barley 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 Barley
Top 25%

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

29 days ago today
Medication Diltiazem
Top 10%

#279 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Barley reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Barley and Diltiazem records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Barley

What is Barley?

Barley
  • High cholesterol
  • Heart health support
  • Blood sugar support
  • Digestive regularity and fiber
  • General nutrition

Barley is a nutritious whole grain that is a good source of soluble fiber called beta-glucan, which has solid evidence for modestly lowering LDL ('bad') cholesterol when eaten regularly. It is safe as a food for most people, but those with celiac disease or gluten sensitivity should avoid it since it contains gluten. Talk to your pharmacist or doctor before using concentrated barley supplements, especially if you have a health condition.

Hordeum vulgare · Poaceae · Grain (seed), and sometimes young leaves/grass and bran · Whole grain, flour, flakes, barley bran, beta-glucan supplements, barley grass powder, tea, and capsules

An interaction check asks whether these two react with each other — it does not ask whether Barley is a good idea for someone in your situation. Here is what our Barley record says about it on its own.

Barley: dosing

There is no single official supplement dose for barley. For cholesterol benefits, research has generally used a few grams of barley beta-glucan per day, taken as part of the diet, but the exact amount can vary by product.Because products differ widely in strength and form, the best approach is to follow the directions on the product label.

From our Barley monograph — the full record covers uses, side effects and every documented interaction.

Read the full Barley 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.

Most-Reported Side Effects for Diltiazem

From FAERS, the FDA’s public side-effect reporting system (34,400 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 3,309 reports
Fatigue 2,733 reports
Nausea 2,454 reports
Dizziness 2,174 reports
Diarrhea 2,113 reports
See full Diltiazem drug information
Keep checking

Other Drugs & Barley

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

0Major
1Moderate
0Minor
2,828No known interaction
1 Moderate 2,828 No interaction
Moderate

1 interaction

No interaction 2,828 drugs checked — show the list

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

Showing the 60 most looked-up of 2,828 medications checked with no known interaction — see the full Barley list.

See the full Barley interactions page
See every supplement checked against Diltiazem, ranked by severity
Evidence & sources

Barley References

The 15 references that drive our Barley monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  2. Fernandez-Anaya S, Crespo JF, Rodriguez JR, et al. Beer anaphylaxis. J Allergy Clin Immunol 1999;103:959-60.
  3. Lembo A, Camilleri M. Chronic constipation. N Engl J Med 2003;349:1360-8. . PubMed
  4. Ferre, I., Giraldez, F. J., Alvarez-Bujidos, M. L., and Mantecon, A. R. Influence of barley supplement on plasma concentration of triclabendazole metabolites in sheep. Vet.Rec. 11-22-1997;141(21):549-551. PubMed
  5. Curioni, A., Santucci, B., Cristaudo, A., Canistraci, C., Pietravalle, M., Simonato, B., and Giannattasio, M. Urticaria from beer: an immediate hypersensitivity reaction due to a 10- kDa protein derived from barley. Clin Exp Allergy 1999;29(3):407-413. PubMed
  6. Fernandez-Anaya, S., Crespo, J. F., Rodriguez, J. R., Daroca, P., Carmona, E., Herraez, L., and Lopez-Rubio, A. Beer anaphylaxis. J Allergy Clin Immunol. 1999;103(5 Pt 1):959-960.
  7. Cronin, E. Contact dermatitis from barley dust. Contact Dermatitis 1979;5(3):196. PubMed
  8. Block, G., Tse, K. S., Kijek, K., Chan, H., and Chan-Yeung, M. Baker's asthma. Studies of the cross-antigenicity between different cereal grains. Clin Allergy 1984;14(2):177-185.
  9. van Ketel, W. G. Immediate type allergy to malt in beer. Contact Dermatitis 1980;6(4):297-298. PubMed
  10. Ellis, H. J., Doyle, A. P., Day, P., Wieser, H., and Ciclitira, P. J. Demonstration of the presence of coeliac-activating gliadin-like epitopes in malted barley. Int Arch Allergy Immunol. 1994;104(3):308-310. PubMed
  11. Vidal, C. and Gonzalez-Quintela, A. Food-induced and occupational asthma due to barley flour. Ann Allergy Asthma Immunol. 1995;75(2):121-124.
  12. Gutgesell, C. and Fuchs, T. Contact urticaria from beer. Contact Dermatitis 1995;33(6):436-437. PubMed
  13. Baker, P. G. and Read, A. E. Oats and barley toxicity in coeliac patients. Postgrad.Med J 1976;52(607):264-268. PubMed
  14. Nakase, M., Usui, Y., Alvarez-Nakase, A. M., Adachi, T., Urisu, A., Nakamura, R., Aoki, N., Kitajima, K., and Matsuda, T. Cereal allergens: rice-seed allergens with structural similarity to wheat and barley allergens. Allergy 1998;53(46 Suppl):55-57. PubMed
  15. Pereira, F., Rafael, M., and Lacerda, M. H. Contact dermatitis from barley. Contact Dermatitis 1998;39(5):261-262. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Barley and Diltiazem Together: Common Questions

Is it safe to take Barley with Diltiazem?
We do not list a known interaction between Barley and Diltiazem. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Barley and Diltiazem have any of the same side effects?
Yes — our sources link each of them separately to 9 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Barley and Diltiazem used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Barley in each. That is a conversation for your prescriber, especially if Diltiazem is being adjusted to a target.
How was the Barley and Diltiazem combination checked?
Interactions in our licensed database are recorded against drug classes. Diltiazem is filed under 9 classifications, and Barley has documented interactions with 1 drug class — none of Diltiazem's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Barley interact with any other medications?
Yes. Barley has 1 documented drug interaction in our database — Diltiazem is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Diltiazem interact with any supplements?
Yes. Diltiazem has documented interactions with 260 supplements in our database — Barley is not one of them. The Diltiazem interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Barley monograph Uses, safety profile, and every drug interaction in one place Diltiazem drug information The full plain-English guide to this medication Diltiazem supplement interactions Every supplement checked against Diltiazem, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 15 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Diltiazem and Barley?

Our pharmacists answer your medication & supplement questions — free.

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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.