Drug side effects
diltiazem Side Effects
The reactions most often reported to the FDA for diltiazem (also sold as Cardizem, Tiazac), with demographics, serious outcomes, and reporting trends.
Data updated 2026-05-15
- 33,620
- FAERS reports
Data from the FDA Adverse Event Reporting System (FAERS), 2003 to 2025. A FAERS report records a temporal association, not proof of cause. See our methodology for how figures are compiled and de-duplicated.
The most commonly reported side effects of diltiazem come from 33,620 reports to the FDA, broken down here by frequency, patient demographics, and serious outcomes.
This page analyzes 33,620 reports to the FDA Adverse Event Reporting System (FAERS) for diltiazem (Cardizem): the reactions reported most often, who reported them, serious outcomes such as hospitalization, and year-over-year trends. A FAERS report does not prove the drug caused the effect, and report volume tracks how widely a drug is used, not how likely an effect is for any one person. Educational information, not medical advice.
Total Reports
33,620
Reports Mentioning Death
4,917
14.6% of reports — not proof the medicine caused the death
Hospitalizations
14,360
42.7% of reports
Top Indication
Product Used For Unknown Indication
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 4,917 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 1,209 |
| DYSPNOEA | 679 |
| FATIGUE | 555 |
| DIARRHOEA | 526 |
| DIZZINESS | 506 |
| NAUSEA | 482 |
| PNEUMONIA | 462 |
| HEADACHE | 458 |
| COMPLETED SUICIDE | 451 |
| DECREASED APPETITE | 449 |
| VOMITING | 444 |
| PAIN | 443 |
| PYREXIA | 420 |
| ARTHRALGIA | 415 |
| ASTHENIA | 409 |
| INJURY | 407 |
| PRURITUS | 401 |
| CONDITION AGGRAVATED | 366 |
| HYPERTENSION | 356 |
| ANXIETY | 355 |
Reactions in Hospitalization Reports
Top reactions in 14,360 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| DYSPNOEA | 1,868 |
| PAIN | 1,451 |
| ATRIAL FIBRILLATION | 1,358 |
| FALL | 1,333 |
| PNEUMONIA | 1,268 |
| FATIGUE | 1,183 |
| HYPOTENSION | 1,162 |
| NAUSEA | 993 |
| ASTHENIA | 953 |
| DIARRHOEA | 928 |
| DIZZINESS | 882 |
| PAIN IN EXTREMITY | 843 |
| CARDIAC FAILURE CONGESTIVE | 840 |
| CHEST PAIN | 808 |
| PYREXIA | 755 |
| CONDITION AGGRAVATED | 754 |
| CONSTIPATION | 746 |
| HEADACHE | 729 |
| MYOCARDIAL INFARCTION | 725 |
Nearby, Related Medications
What the FAERS Data Reveals About diltiazem Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 33,620 voluntary reports linked to diltiazem and its brand equivalents (Cardizem, Tiazac), spanning 2003 through 2025. Of those, 4,917 (14.6%) listed death as an outcome and 14,360 (42.7%) involved hospitalization. The most common indication reported alongside adverse events was Product Used For Unknown Indication.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 64% were female and 36% male; age distribution skews toward 75+, with 7,764 reports in that bracket. The single most reported reaction is dyspnoea with 3,202 submissions, followed by fatigue and nausea.
How to read these numbers
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice, speak with a licensed clinician about any side-effect concerns.
Drugs With a Similar FAERS Report Volume
Other medications with a total FDA adverse-event report count closest to diltiazem's 33,620.
Read our methodology - how this data is sourced, computed, and verified.