Drug & supplement interaction

Turmeric + 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

Diltiazem falls into 2 drug categories that Turmeric can interact with; the most serious is rated moderate. Turmeric might increase or decrease levels of drugs metabolized by CYP3A4.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Turmeric and Diltiazem

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Turmeric interacts with whole categories of medication. Diltiazem falls into 2 of those categories, so it can interact with Turmeric in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

1 of 2

Why this applies to Diltiazem

Diltiazem falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Turmeric interacts with.

Turmeric might increase or decrease levels of drugs metabolized by CYP3A4.
In vitro and animal research show that turmeric and its constituents curcumin and curcuminoids inhibit CYP3A4. Also, 8 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking turmeric and cancer medications that are CYP3A4 substrates, including everolimus, ruxolitinib, ibrutinib, and palbociclib, and bortezomib. In another case report, a transplant patient presented with acute nephrotoxicity and elevated tacrolimus levels after consuming turmeric powder at a dose of 15 or more spoonfuls daily for ten days prior. It was thought that turmeric increased levels of tacrolimus due to CYP3A4 inhibition.
Conversely, other in vitro research suggests that turmeric induces CYP3A4 activity, leading to reduced levels of CYP3A4 substrates. An animal model suggests that induction of CYP3A4 occurs after daily curcumin use for 1 week. However, the induction of CYP3A4 by turmeric has not been reported in humans.
Severity Moderate Likelihood Possible Evidence D

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.

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

Here's the deal with these two. Your body relies on a liver enzyme called CYP3A4 to break down diltiazem and keep its levels in check. Turmeric, mostly its curcumin part, may slow that enzyme down a bit. If that happens, diltiazem could build up more than expected, which might mean a stronger drop in blood pressure, dizziness, a slower heartbeat, or swelling in your ankles.

The good news: this concern comes mainly from lab and animal studies, not solid human evidence, and the few real-world reports involved very heavy turmeric use. A little turmeric in your cooking is very unlikely to cause trouble. Concentrated curcumin capsules are the bigger question mark. Before starting one, just check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Appiah-Opong, R., Commandeur, J. N., Vugt-Lussenburg, B., and Vermeulen, N. P. Inhibition of human recombinant cytochrome P450s by curcumin and curcumin decomposition products. Toxicology 6-3-2007;235(1-2):83-91. PubMed
  2. Hou, X. L., Takahashi, K., Kinoshita, N., Qiu, F., Tanaka, K., Komatsu, K., Takahashi, K., and Azuma, J. Possible inhibitory mechanism of Curcuma drugs on CYP3A4 in 1alpha,25 dihydroxyvitamin D3 treated Caco-2 cells. Int.J Pharm 6-7-2007;337(1-2):169-177.
  3. Valentine, S. P., Le Nedelec, M. J., Menzies, A. R., Scandlyn, M. J., Goodin, M. G., and Rosengren, R. J. Curcumin modulates drug metabolizing enzymes in the female Swiss Webster mouse. Life Sci. 4-11-2006;78(20):2391-2398. PubMed
  4. Nayeri A, Wu S, Adams E, et al. Acute Calcineurin Inhibitor Nephrotoxicity Secondary to Turmeric Intake: A Case Report. Transplant Proc. 2017;49(1):198-200. PubMed
  5. Haron MH, Dale O, Martin K, et al. Evaluation of the Herb-Drug Interaction Potential of Commonly Used Botanicals on the US Market with Regard to PXR- and AhR-Mediated Influences on CYP3A4 and CYP1A2. J Diet Suppl 2022. PubMed
  6. Pochet S, Lechon AS, Lescrainier C, et al. Herb-anticancer drug interactions in real life based on VigiBase, the WHO global database. Sci Rep 2022;12(1):14178. PubMed
  7. Dibaei M, Hosseini A, Lavasani H, Kiani-Dehkordi B, Rouini M. Assessment of metabolic interaction between curcumin and tramadol using the isolated perfused rat liver. Heliyon 2024;10(15):e35070. PubMed
Minor

P-GLYCOPROTEIN SUBSTRATES

2 of 2

Diltiazem also falls under P-GLYCOPROTEIN SUBSTRATES.

Theoretically, turmeric might increase the absorption of P-glycoprotein substrates.
In vitro and animal research shows that curcuminoids and other constituents found in turmeric can inhibit P-glycoprotein expression and activity.
Severity Minor Likelihood Possible Evidence D

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.

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

Here's the gist for diltiazem and turmeric. Your body uses a kind of pump called P-glycoprotein to move certain drugs out of your gut and limit how much gets absorbed. Diltiazem is one of those drugs. In lab dishes and animal studies, the curcumin in turmeric seems to slow that pump down a bit, which could let slightly more diltiazem into your bloodstream.

If that happened, you might notice more of diltiazem's usual effects, like low blood pressure, dizziness, a slower heartbeat, or swollen ankles. But I want to keep this in perspective. This is rated a minor interaction based only on lab and animal data, not real patients, and the spice amounts in food are very unlikely to matter. Concentrated curcumin capsules are where I'd be a little more cautious. If you take one regularly, just mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Junyaprasert, V. B., Soonthornchareonnon, N., Thongpraditchote, S., Murakami, T., and Takano, M. Inhibitory effect of Thai plant extracts on P-glycoprotein mediated efflux. Phytother.Res 2006;20(1):79-81. PubMed
  2. Ampasavate, C., Sotanaphun, U., Phattanawasin, P., and Piyapolrungroj, N. Effects of Curcuma spp. on P-glycoprotein function. Phytomedicine. 2010;17(7):506-512. PubMed
  3. Hou, X. L., Takahashi, K., Tanaka, K., Tougou, K., Qiu, F., Komatsu, K., Takahashi, K., and Azuma, J. Curcuma drugs and curcumin regulate the expression and function of P-gp in Caco-2 cells in completely opposite ways. Int.J Pharm 6-24-2008;358(1-2):224-2 PubMed
  4. Choi, B. H., Kim, C. G., Lim, Y., Shin, S. Y., and Lee, Y. H. Curcumin down-regulates the multidrug-resistance mdr1b gene by inhibiting the PI3K/Akt/NF kappa B pathway. Cancer Lett. 1-18-2008;259(1):111-118.
  5. Zhang, W., Tan, T. M., and Lim, L. Y. Impact of curcumin-induced changes in P-glycoprotein and CYP3A expression on the pharmacokinetics of peroral celiprolol and midazolam in rats. Drug Metab Dispos. 2007;35(1):110-115. PubMed
  6. Limtrakul, P., Chearwae, W., Shukla, S., Phisalphong, C., and Ambudkar, S. V. Modulation of function of three ABC drug transporters, P-glycoprotein (ABCB1), mitoxantrone resistance protein (ABCG2) and multidrug resistance protein 1 (ABCC1) by tetrahydrocu
  7. Holland, M. L., Panetta, J. A., Hoskins, J. M., Bebawy, M., Roufogalis, B. D., Allen, J. D., and Arnold, J. C. The effects of cannabinoids on P-glycoprotein transport and expression in multidrug resistant cells. Biochem.Pharmacol 4-14-2006;71(8):1146-1154 PubMed
  8. Tang, X. Q., Bi, H., Feng, J. Q., and Cao, J. G. Effect of curcumin on multidrug resistance in resistant human gastric carcinoma cell line SGC7901/VCR. Acta Pharmacol Sin. 2005;26(8):1009-1016. PubMed
  9. Nabekura, T., Kamiyama, S., and Kitagawa, S. Effects of dietary chemopreventive phytochemicals on P-glycoprotein function. Biochem.Biophys.Res Commun. 2-18-2005;327(3):866-870. PubMed
  10. Romiti, N., Tongiani, R., Cervelli, F., and Chieli, E. Effects of curcumin on P-glycoprotein in primary cultures of rat hepatocytes. Life Sci. 1998;62(25):2349-2358. PubMed
  11. Yue, G. G., Cheng, S. W., Yu, H., Xu, Z. S., Lee, J. K., Hon, P. M., Lee, M. Y., Kennelly, E. J., Deng, G., Yeung, S. K., Cassileth, B. R., Fung, K. P., Leung, P. C., and Lau, C. B. The role of turmerones on curcumin transportation and P-glycoprotein acti
  12. Pochet S, Lechon AS, Lescrainier C, et al. Herb-anticancer drug interactions in real life based on VigiBase, the WHO global database. Sci Rep 2022;12(1):14178. 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

Turmeric Also Interacts With Other Medications

Turmeric has 1,055 moderate, 77 minor known drug interactions in our database — the Diltiazem one above is among them. If you take anything else, check it against the full list below.

Moderate 1,055 Minor 77 No known interaction 1,698 (incl. Diltiazem)
Taking anything else?

Check Another of Your Medications Against Turmeric

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

From our Q&A

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

We hold 1,368 real supplement products containing Turmeric, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Turmeric. Your product may carry other ingredients that interact with Diltiazem too, on top of Turmeric — 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 Turmeric 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 Turmeric
Top 5%

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

29 days ago today
Medication Diltiazem
Top 25%

#285 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 Turmeric

What is Turmeric?

Turmeric
  • Joint pain and arthritis
  • Inflammation
  • Digestive upset
  • Antioxidant support
  • Skin conditions

Turmeric is a popular spice whose main active compounds, curcuminoids, are studied mostly for inflammation and joint pain. Some research is promising, but quality is mixed and curcumin is poorly absorbed on its own. For most people, dietary amounts are safe, but talk to your pharmacist or doctor before taking concentrated supplements, especially if you are pregnant, nursing, or have a medical condition.

Read the full Turmeric 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 & Turmeric

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

0Major
1,055Moderate
77Minor
1,697No known interaction
1,055 Moderate 77 Minor 1,697 No interaction
Moderate

1,055 interactions

Showing 60 of 1,055 moderate interactions — see all 1,055 on the Turmeric page.

Minor

77 interactions

Showing 60 of 77 minor interactions — see all 77 on the Turmeric page.

No interaction 1,697 drugs checked — show the list

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

Showing the 60 most looked-up of 1,697 medications checked with no known interaction — see the full Turmeric list.

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

Can you take Turmeric 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.
Why are there 2 interactions listed for Turmeric and Diltiazem?
Diltiazem belongs to more than one drug category, and Turmeric interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Turmeric 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 Turmeric?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.