Drug & supplement interaction

Bergamot + 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

Bergamot has a moderate interaction with Diltiazem. Theoretically, topical bergamot essential oil might increase the risk of side effects when used along with photosensitizing drugs.

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

Bergamot and Diltiazem

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

Moderate

PHOTOSENSITIZING DRUGS

Why this applies to Diltiazem

Diltiazem falls under PHOTOSENSITIZING DRUGS — the group Bergamot interacts with.

Theoretically, topical bergamot essential oil might increase the risk of side effects when used along with photosensitizing drugs.
Bergamot contains bergapten, which has photosensitizing 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 know about pairing bergamot with diltiazem: this particular interaction is about your skin's sensitivity to sunlight, not about how your blood pressure medicine works. Bergamot, especially its essential oil, contains a compound called bergapten that can make your skin react more strongly to the sun. Diltiazem itself can occasionally cause a similar light-sensitivity effect, so using them together might add up and raise your odds of a sunburn-like rash or quicker burning outdoors.

I'll be honest with you: this is a theoretical concern based on how these compounds behave, not strong real-world data, and it mostly applies to the topical oil rather than eating the fruit. It won't change how well diltiazem controls your blood pressure or chest pain. Still, use sunscreen, and check with your pharmacist before starting a bergamot product.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Naganuma M, Hirose S, Nakayama Y, et al. A study of the phototoxicity of lemon oil. Arch Dermatol Res 1985;278:31-6. . PubMed
  2. Kaddu, S., Kerl, H., and Wolf, P. Accidental bullous phototoxic reactions to bergamot aromatherapy oil. J.Am.Acad.Dermatol. 2001;45(3):458-461. PubMed
  3. Gruson, L. M. and Chang, M. W. Berloque dermatitis mimicking child abuse. Arch.Pediatr.Adolesc.Med. 2002;156(11):1091-1093. PubMed
  4. Weisenseel, P. and Woitalla, S. [Toxic mustard plaster dematitis and phototoxic dematitis after application of bergamot oil]. MMW.Fortschr.Med. 12-15-2005;147(51-52):53, 55.
  5. Placzek, M., Fromel, W., Eberlein, B., Gilbertz, K. P., and Przybilla, B. Evaluation of phototoxic properties of fragrances. Acta Derm.Venereol. 2007;87(4):312-316. PubMed
  6. Morliere, P., Huppe, G., Averbeck, D., Young, A. R., Santus, R., and Dubertret, L. In vitro photostability and photosensitizing properties of bergamot oil. Effects of a cinnamate sunscreen. J.Photochem.Photobiol.B 1990;7(2-4):199-208. PubMed
  7. Young, A. R., Walker, S. L., Kinley, J. S., Plastow, S. R., Averbeck, D., Morliere, P., and Dubertret, L. Phototumorigenesis studies of 5-methoxypsoralen in bergamot oil: evaluation and modification of risk of human use in an albino mouse skin model. J.P PubMed
  8. Girard, J., Unkovic, J., Delahayes, J., and Lafille, C. [Phototoxicity of Bergamot oil. Comparison between humans and guinea pigs]. Dermatologica 1979;158(4):229-243.
  9. Zaynoun, S. T., Johnson, B. E., and Frain-Bell, W. A study of oil of bergamot and its importance as a phototoxic agent. II. Factors which affect the phototoxic reaction induced by bergamot oil and psoralen derivatives. Contact Dermatitis 1977;3(5):225-23 PubMed
  10. Zacher, K. D. and Ippen, H. [Contact dermatitis caused by bergamot oil]. Derm.Beruf.Umwelt. 1984;32(3):95-97.
  11. Yasui, Y. and Hirone, T. Action spectrum for bergamot-oil phototoxicity measured by sunburn cell counting. J.Dermatol. 1994;21(5):319-322. PubMed
  12. Zaynoun, S. T., Johnson, B. E., and Frain-Bell, W. A study of oil of bergamot and its importance as a phototoxic agent. I. Characterization and quantification of the photoactive component. Br.J.Dermatol. 1977;96(5):475-482. 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

Bergamot Also Interacts With Other Medications

Bergamot has 409 moderate 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 409 No known interaction 2,421 (incl. Diltiazem)
Taking anything else?

Check Another of Your Medications Against Bergamot

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

From our Q&A

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

We hold 47 real supplement products containing Bergamot, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bergamot. Your product may carry other ingredients that interact with Diltiazem too, on top of Bergamot — 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 Bergamot 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 Bergamot
Top half

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

29 days ago today
Medication Diltiazem
Top 25%

#352 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 Bergamot

What is Bergamot?

Bergamot
  • High cholesterol
  • Heart and metabolic health
  • Anxiety and stress (aromatherapy)
  • Antimicrobial/antiseptic
  • Skin care and fragrance

Bergamot is a Mediterranean citrus fruit, and its standardized extract is most often used to support cholesterol and heart health, with some early but promising research. The essential oil is widely used for fragrance and aromatherapy but should not be taken by mouth, and it can make skin more sensitive to sunlight. Talk with your pharmacist or doctor before using bergamot supplements, especially if you take medicine for cholesterol or blood sugar.

Read the full Bergamot 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 & Bergamot

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

0Major
409Moderate
0Minor
2,420No known interaction
409 Moderate 2,420 No interaction
Moderate

409 interactions

Showing 60 of 409 moderate interactions — see all 409 on the Bergamot page.

No interaction 2,420 drugs checked — show the list

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

Showing the 60 most looked-up of 2,420 medications checked with no known interaction — see the full Bergamot list.

See the full Bergamot 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
Bergamot 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 Bergamot and Diltiazem Together: Common Questions

Can you take Bergamot 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 Bergamot 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 Bergamot?

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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.