Drug & supplement interaction

Calcium + Diltiazem, Enalapril

Diltiazem, Enalapril brand name: Teczem.

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

Diltiazem, Enalapril falls into 2 drug categories that Calcium can interact with; the most serious is rated moderate. Theoretically, calcium may reduce the therapeutic effects of diltiazem.

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

Calcium and Diltiazem, Enalapril

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

Why Are There 2 Interactions?

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

Moderate

DILTIAZEM (Cardizem, others)

1 of 2
Theoretically, calcium may reduce the therapeutic effects of diltiazem.
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.
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

Your medicine pairs diltiazem (a calcium channel blocker) with enalapril, both of which help lower blood pressure. Here's the idea behind this one: diltiazem works by quieting the flow of calcium into your heart and blood vessel cells. The thinking is that loading up on a lot of extra calcium could push against that effect and make the diltiazem part work a little less well. If that happened, you might notice your blood pressure or heart rate creeping back up.

I want to be honest about how shaky this evidence is. It's mostly theoretical and based on scattered reports, not strong studies. Everyday calcium from food, or a sensible supplement dose, is unlikely to cause trouble for most people. Still, before adding a calcium supplement, run it by your pharmacist or doctor, especially if you have kidney issues.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Bar-Or D, Yoel G. Calcium and calciferol antagonize effect of verapamil in atrial fibrillation. Br Med J 1981;282:1585-6.
Minor

CALCIUM CHANNEL BLOCKERS

2 of 2

Why this applies to Diltiazem, Enalapril

Diltiazem, Enalapril falls under CALCIUM CHANNEL BLOCKERS — the group Calcium interacts with.

Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects. But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Teczem combines diltiazem (a calcium channel blocker) with enalapril (a blood pressure medicine), and both work to relax your blood vessels and ease the heart's workload. You might wonder if a calcium supplement would push back against the calcium-blocking part. Here's the reassuring news: this concern only applies to calcium given by IV in a hospital, where doctors deliberately use it to counter a calcium channel blocker, for example during an overdose.

The calcium you swallow as a pill or get from food does not work this way. There's no real-world evidence that oral calcium weakens diltiazem or enalapril, so your blood pressure control shouldn't suffer. Still, it never hurts to mention all your supplements to your pharmacist, especially if you have kidney issues.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Moser LR, Smythe MA, Tisdale JE. The use of calcium salts in the prevention and management of verapamil-induced hypotension. Ann Pharmacother 2000;34:622-9. PubMed
  2. Gueguen L, Pointillart A. The bioavailability of dietary calcium. J Am Coll Nutr 2000;19:119s-136s. PubMed
  3. Bania TC, Blaufeux B, Hughes S, et al. Calcium and digoxin vs. calcium alone for severe verapamil toxicity. Acad Emerg Med 2000;7:1089-96. 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

Calcium Also Interacts With Other Medications

Calcium has 7 major, 142 moderate, 18 minor known drug interactions in our database — the Diltiazem, Enalapril one above is among them. If you take anything else, check it against the full list below.

Major 7 Moderate 142 Minor 18 No known interaction 2,663 (incl. Diltiazem, Enalapril)
Taking anything else?

Check Another of Your Medications Against Calcium

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

From our Q&A

Questions About Calcium or Diltiazem, Enalapril

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Calcium or Diltiazem, Enalapril, 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, Enalapril

This page covers Calcium only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Diltiazem, Enalapril page lists 271 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), Asarabacca (major) and Coleus (major).

By severity: 9 major · 220 moderate · 42 minor.

From our pharmacist’s overview on the Diltiazem, Enalapril page

“Anyone taking Teczem (diltiazem with enalapril) for blood pressure should know that most of the 271 supplements with an interaction on file hit the same targets as the drug itself. The bulk either add to its blood-pressure-lowering effect or change how the body handles diltiazem, which is processed by an enzyme called CYP3A4.”

Reviewed by 2 · Jul 18, 2026

Open the Diltiazem, Enalapril interaction page

One more smart check

Taking Calcium as Part of a Dietary Supplement Product? Check It for Interactions

We hold 38,397 real supplement products containing Calcium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Calcium. Your product may carry other ingredients that interact with Diltiazem, Enalapril too, on top of Calcium — 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 Calcium and Diltiazem, Enalapril 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 Calcium
Top 10

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

29 days ago today
Medication Diltiazem, Enalapril
Top half

#1,013 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 Calcium

What is Calcium?

  • Bone health and osteoporosis prevention
  • Dietary calcium deficiency
  • Heartburn relief (calcium carbonate antacids)
  • Supporting healthy teeth
  • High blood pressure support during pregnancy

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet falls short. Most people do best getting calcium from food, and supplements should be used at the lowest dose needed. Talk to your pharmacist or doctor before starting, especially if you have kidney problems or take other medicines.

Read the full Calcium monograph & all interactions
Keep checking

Other Drugs & Calcium

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

7Major
142Moderate
18Minor
2,662No known interaction
7 Major 142 Moderate 18 Minor 2,662 No interaction
Major

7 interactions

Moderate

142 interactions

Showing 60 of 142 moderate interactions — see all 142 on the Calcium page.

Minor

18 interactions

No interaction 2,662 drugs checked — show the list

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

Showing the 60 most looked-up of 2,662 medications checked with no known interaction — see the full Calcium list.

See the full Calcium interactions page
See every supplement checked against Diltiazem, Enalapril, 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
Calcium monograph › Uses, safety, and every drug interaction in one place Diltiazem, Enalapril supplement interactions › Every supplement checked against Diltiazem, Enalapril, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Calcium and Diltiazem, Enalapril Together: Common Questions

Can you take Calcium with Diltiazem, Enalapril?
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 Calcium and Diltiazem, Enalapril?
Diltiazem, Enalapril belongs to more than one drug category, and Calcium 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 Calcium and Diltiazem, Enalapril 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, Enalapril and Calcium?

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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.