Prescription medication · Calcium Channel Blocker
diltiazem
Also sold as Cardizem, Tiazac. Diltiazem is used to treat high blood pressure.
Data updated 2026-05-15
- 33,620
- FDA reportsModerately reported
- 46
- InteractionsMany interactions
- In shortage
- FDA status
What the data shows
diltiazem (Cardizem) is a prescription Calcium Channel Blocker, reported at a middle-of-the-pack volume (33,620 FDA reports), with 46 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
diltiazem (Cardizem) is a prescription Calcium Channel Blocker. Diltiazem is used to treat high blood pressure.
Diltiazem is a medicine that helps lower high blood pressure and prevent chest pain. It belongs to a class of drugs called calcium channel blockers.
Verify with FDA → · CMS NADAC pricing →
Drug Shortage Alert
diltiazem is currently listed as to be discontinued by the FDA. Affected manufacturer: Hospira, Inc., a Pfizer Company.
View all drug shortages →Drug Pricing (NADAC)
Generic Price
$0.23/unit
Generic Available
Yes (32 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Diltiazem is used to treat high blood pressure.
Common side effects
Swelling in your ankles or feet, Headache, Dizziness
Key warnings
Diltiazem can interact with other heart medications.
The sections below are summarized in plain English from diltiazem's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Diltiazem works by relaxing blood vessels, which lowers blood pressure. It also reduces the heart's workload, which can prevent chest pain. This medicine blocks calcium from entering heart and blood vessel cells.
Side Effects (from patient reports)
Based on 33,620 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for diltiazem, by number of reports
- Dyspnoea
Dyspnoea
3,202 reports
- Fatigue
Fatigue
2,638 reports
- Nausea
Nausea
2,372 reports
- Pain
Pain
2,365 reports
- Dizziness
Dizziness
2,091 reports
- Diarrhoea
Diarrhoea
2,045 reports
- Fall
Fall
1,954 reports
- Headache
Headache
1,929 reports
- Atrial Fibrillation
Atrial Fibrillation
1,754 reports
- Asthenia
Asthenia
1,705 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for diltiazem each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where diltiazem sits
diltiazem has more FDA adverse-event reports than 66% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is diltiazem; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 33,620 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2003–2025.
Total Reports
33,620
Reports Mentioning Death
4,917
14.6% of reports — not proof of cause
Hospitalization Reports
14,360
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DYSPNOEA | 3,202 |
| 2 | FATIGUE | 2,638 |
| 3 | NAUSEA | 2,372 |
| 4 | PAIN | 2,365 |
| 5 | DIZZINESS | 2,091 |
| 6 | DIARRHOEA | 2,045 |
| 8 | FALL | 1,954 |
| 9 | HEADACHE | 1,929 |
| 10 | ATRIAL FIBRILLATION | 1,754 |
| 11 | ASTHENIA | 1,705 |
| 12 | PNEUMONIA | 1,605 |
| 13 | ARTHRALGIA | 1,548 |
| 14 | HYPOTENSION | 1,494 |
| 15 | PAIN IN EXTREMITY | 1,449 |
| 16 | MALAISE | 1,411 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Diltiazem can interact with other heart medications. Tell your doctor if you take beta-blockers or digoxin. Using diltiazem with these drugs can cause heart problems. Your doctor may need to adjust your dosages.
Known Drug Interactions
Intervention: For patients taking verapamil, diltiazem, or dronedarone, do not exceed ezetimibe and simvastatin 10 mg/10 mg daily.
Mechanism: Diltiazem can increase the levels of the cholesterol medicine in your blood, which may lead to muscle problems.
Intervention: For patients taking verapamil, diltiazem, or dronedarone, do not exceed VYTORIN 10/10 mg daily.
Mechanism: Diltiazem slows down the breakdown of simvastatin in your body, which can lead to higher levels of the drug in your blood. This increases the risk of serious muscle damage.
Intervention: For patients taking verapamil, diltiazem, or dronedarone, do not exceed ezetimibe and simvastatin 10 mg/10 mg daily.
Mechanism: Diltiazem blocks the enzymes that break down simvastatin, causing the drug to stay in your body longer. This can lead to a higher risk of muscle pain or damage.
albuterol, systemic and inhaled mebendazole amoxicillin medroxyprogesterone ampicillin, with or without sulbactam methylprednisolone atenolol metronidazole azithromycin metoprolol caffeine, dietary ingestion nadolol cefaclor nifedipine co-trimoxazole (trimethoprim and sulfamethoxazole) nizatidine diltiazem norfloxacin dirithromycin ofloxacin enflurane omeprazole famotidine prednisone, prednisolone felodipine ranitidine finasteride rifabutin hydrocortisone roxithromycin isoflurane Sorbitol (purgative doses do not inhibit theophylline absorption) isoniazid sucralfate isradipine terbutaline,...
Mechanism: Diltiazem can slow down the liver's ability to break down theophylline. This can cause the medicine to build up in your body and reach toxic levels.
Rifampin : Coadministration of rifampin with diltiazem lowered the diltiazem plasma concentrations to undetectable levels. Avoid coadministration of diltiazem with rifampin or any known CYP3A4 inducer.
Mechanism: Rifampin speeds up how quickly your body breaks down diltiazem, which can cause the diltiazem to disappear from your blood and stop working.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
Can I take diltiazem with other medications?
How long does it take for diltiazem to start working?
Can I drink alcohol while taking diltiazem?
What should I do if I experience side effects?
Can I stop taking diltiazem suddenly?
Does diltiazem affect my ability to drive or operate machinery?
How often should I check my blood pressure?
Can diltiazem cure my high blood pressure or angina?
What if I have kidney or liver problems?
Are there any foods I should avoid while taking diltiazem?
What are the common side effects of diltiazem?
Does diltiazem interact with other medications?
What drug class is diltiazem?
What pregnancy or breastfeeding source fields are listed for diltiazem?
Has diltiazem been recalled?
Is diltiazem currently in shortage?
Active Recalls
cGMP Deviations: Presence of N-nitroso-Desmethyl-Diltiazem impurity above FDA recommended interim limit.
Glenmark Pharmaceuticals Inc., USA
cGMP Deviations: Presence of N-nitroso-Desmethyl-Diltiazem impurity above FDA recommended interim limit.
Glenmark Pharmaceuticals Inc., USA
cGMP Deviations: Presence of N-nitroso-Desmethyl-Diltiazem impurity above FDA recommended interim limit.
Glenmark Pharmaceuticals Inc., USA
Related Medications in Calcium Channel Blocker
Other drugs grouped near diltiazem - same-class peers and common alternatives.
acebutolol
Sectral
Acebutolol is a medicine that helps lower blood pressure and control irregular heartbeats.
Compare with diltiazem →
aliskiren
Tekturna
Tekturna is a medicine used to treat high blood pressure.
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amiloride
Midamor
Amiloride is a water pill that helps your body hold onto potassium.
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amlodipine
Norvasc
Amlodipine (Norvasc) is a drug that lowers blood pressure and treats chest pain.
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amlodipine/benazepril
Lotrel
Lotrel is a combination medicine that contains amlodipine and benazepril.
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Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for diltiazem: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 33,620.
- telmisartan Δ 9 reports · Angiotensin II Receptor Blocker (ARB) 33,611reports
- candesartan Δ 143 reports · Angiotensin II Receptor Blocker (ARB) 33,477reports
- clarithromycin Δ 373 reports · Macrolide Antibiotic 33,247reports
- tapentadol Δ 566 reports · Opioid / Norepinephrine Reuptake Inhibitor 33,054reports
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 14.63%.
- roflumilast Δ 0.01 pts · 6,450 reports · PDE4 Inhibitor 14.62%death share
- theophylline Δ 0.06 pts · 11,723 reports · Methylxanthine Bronchodilator 14.57%death share
- quetiapine Δ 0.08 pts · 185,533 reports · Atypical Antipsychotic 14.54%death share
- fluvastatin Δ 0.11 pts · 3,948 reports · HMG-CoA Reductase Inhibitor (Statin) 14.51%death share
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for diltiazem
The FDA label for diltiazem (sold under brand names such as Cardizem, Tiazac) classifies it as a prescription-only medication in the Calcium Channel Blocker class. Diltiazem is used to treat high blood pressure. Official labeling lists 5 commonly reported side effects, including Swelling in your ankles or feet, Headache, Dizziness.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 33,620 voluntary reports. The database also lists 46 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS shows a generic unit cost of $0.23.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 3 recall records on file), and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC). Shortage status: FDA Drug Shortages Database.
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.
Last updated: August 20, 2025
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages