Drug & supplement interaction

Rabdosia Rubescens + 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 Rabdosia Rubescens can interact with; the most serious is rated moderate. Rabdosia rubescens might increase levels of p-glycoprotein substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Rabdosia Rubescens and Diltiazem

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

Why Are There 2 Interactions?

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

Moderate

P-GLYCOPROTEIN SUBSTRATES

1 of 2

Why this applies to Diltiazem

Diltiazem falls under P-GLYCOPROTEIN SUBSTRATES — the group Rabdosia Rubescens interacts with.

Rabdosia rubescens might increase levels of p-glycoprotein substrates. In vitro research shows that Rabdosia rubescens extract inhibits p-glycoprotein levels and activity. Drugs that might be affected include some chemotherapeutic agents (doxorubicin, etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), protease inhibitors (amprenavir, indinavir, nelfinavir, saquinavir), H2 antagonists (cimetidine, ranitidine), some calcium channel blockers (diltiazem, verapamil), digoxin, corticosteroids, erythromycin, cisapride (Propulsid), fexofenadine (Allegra), cyclosporine, loperamide (Imodium), quinidine, and others.
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 gist for diltiazem: your body uses a kind of cellular bouncer called p-glycoprotein to push this drug back out of cells and gut lining. In lab studies (test tubes only, not people), Rabdosia rubescens seems to slow that bouncer down. If that happened in a real person, more diltiazem could stay in your system, which could nudge its effects up a notch.

For diltiazem, that might mean things like lower blood pressure, dizziness or lightheadedness, a slower heart rate, or swelling in the ankles. To be honest, the evidence here is weak and only from cell studies, so this is more theoretical than proven. Still, since diltiazem affects your heart and blood pressure, please check with your pharmacist or doctor before pairing it with this herb.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Li F, Fan J, Wu Z, et al. Reversal effects of Rabdosia rubescens extract on multidrug resistance of MCF-7/Adr cells in vitro. Pharm Biol. 2013;51(9):1196-203.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Diltiazem also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

In vitro research shows that oridonin, a constituent of Rabdosia rubescens, induces cytochrome P450 3A4 (CYP3A4) enzyme. Also, in an animal model, oridonin induces a gene homologous to CYP3A4. So far, this interaction has not been reported in humans. However, watch for a decrease in the levels of drugs metabolized by CYP3A4 in patients taking Rabdosia rubescens. Some drugs metabolized by CYP3A4 that might be affected are some benzodiazepines such as alprazolam (Xanax), diazepam (Valium), midazolam (Versed), triazolam (Halcion); calcium channel blockers such as amlodipine (Norvasc), diltiazem (Cardizem, Dilacor, others), felodipine (Plendil), verapamil (Calan, Verelan, others); cyclosporine (Neoral, Sandimmune); some HIV antivirals such as indinavir (Crixivan), ritonavir (Norvir), saquinavir (Fortovase, Invirase); some HMG CoA reductase inhibitors such as atorvastatin (Lipitor), lovastatin (Mevacor); some macrolide antibiotics such as erythromycin and clarithromycin (Biaxin); quinidine; and many others.
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 gist for diltiazem: your body relies on an enzyme called CYP3A4 to break it down. Lab and animal research suggests a compound in Rabdosia rubescens (oridonin) may speed up that enzyme. If that happens in people, your body could clear diltiazem a little faster, which may leave less of it working to lower your blood pressure and ease chest pain. In plain terms, the herb could weaken the medicine, so your blood pressure might creep up or angina might be less controlled.

I'll be honest with you, this is based only on test-tube and animal studies, not real patients, so the concern is theoretical. Still, since blood pressure control matters, please check with your pharmacist or doctor before adding this supplement, and don't change your diltiazem on your own.

Contact Dr. Brian directly if you have additional questions on this interaction

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

Rabdosia Rubescens Also Interacts With Other Medications

Rabdosia Rubescens has 713 moderate, 69 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 713 Minor 69 No known interaction 2,048 (incl. Diltiazem)
Taking anything else?

Check Another of Your Medications Against Rabdosia Rubescens

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

From our Q&A

Questions About Rabdosia Rubescens 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 Rabdosia Rubescens 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 Rabdosia Rubescens 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

How much people look this up

Where Rabdosia Rubescens 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 Rabdosia Rubescens
Steady interest

#998 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 Rabdosia Rubescens

What is Rabdosia Rubescens?

Rabdosia Rubescens
  • Sore throat and respiratory complaints
  • Inflammation
  • Antimicrobial support
  • Digestive complaints
  • Traditional cancer support

Rabdosia rubescens is a Chinese herb traditionally used for sore throats, inflammation, and infections, and its compound oridonin has drawn lab interest for possible anticancer effects. However, strong human evidence is lacking for any use, and safety has not been well studied, so talk with your pharmacist or doctor before trying it.

Read the full Rabdosia Rubescens 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 & Rabdosia Rubescens

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

0Major
713Moderate
69Minor
2,047No known interaction
713 Moderate 69 Minor 2,047 No interaction
Moderate

713 interactions

Showing 60 of 713 moderate interactions — see all 713 on the Rabdosia Rubescens page.

Minor

69 interactions

Showing 60 of 69 minor interactions — see all 69 on the Rabdosia Rubescens page.

No interaction 2,047 drugs checked — show the list

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

Showing the 60 most looked-up of 2,047 medications checked with no known interaction — see the full Rabdosia Rubescens list.

See the full Rabdosia Rubescens 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
Rabdosia Rubescens 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 Rabdosia Rubescens and Diltiazem Together: Common Questions

Can you take Rabdosia Rubescens 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 Rabdosia Rubescens and Diltiazem?
Diltiazem belongs to more than one drug category, and Rabdosia Rubescens 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 Rabdosia Rubescens 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 Rabdosia Rubescens?

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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.