Prescription medication · Calcium Channel Blocker
isradipine
Also sold as DynaCirc. Isradipine capsules are used to treat high blood pressure.
Data updated 2026-05-15
- 541
- FDA reportsRarely reported
- 9
- InteractionsFew interactions
- $2.52
- Generic price (NADAC)
What the data shows
isradipine (DynaCirc) is a prescription Calcium Channel Blocker, among the least-reported drugs the FDA tracks (541 FDA reports), with 9 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.
isradipine (DynaCirc) is a prescription Calcium Channel Blocker. Isradipine capsules are used to treat high blood pressure.
Isradipine is a drug that helps lower high blood pressure. It belongs to a class of drugs called calcium channel blockers.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$2.52/unit
Generic Available
Yes (2 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Isradipine capsules are used to treat high blood pressure.
Common side effects
Headache, Dizziness, Swelling in ankles or feet
Key warnings
If you are taking cimetidine, your doctor should watch you closely for side effects when you start isradipine.
The sections below are summarized in plain English from isradipine's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Isradipine blocks calcium from entering certain cells. This action relaxes blood vessels, which lowers blood pressure. Lowering blood pressure helps prevent strokes, heart attacks, and kidney problems.
How to Take It
Take isradipine as your doctor tells you. The usual starting dose is 2.5 mg twice a day. You can take it with or without food. Your doctor may increase your dose every 2 to 4 weeks, up to 20 mg per day.
This is a plain-language summary of isradipine's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if isradipine will harm your unborn baby. Talk to your doctor about the risks and benefits of taking isradipine while breastfeeding.
This is a plain-language summary of isradipine's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of isradipine's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store isradipine capsules at room temperature (68° to 77°F) in a tightly closed container, away from light.
Side Effects (from patient reports)
Based on 541 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for isradipine, by number of reports
- The medicine is interacting with another medicine
The medicine is interacting with another medicine
31 reports
- Difficulty breathing
Difficulty breathing
31 reports
- High blood pressure
High blood pressure
29 reports
- Feeling sick to your stomach
Feeling sick to your stomach
27 reports
- Sudden kidney damage
Sudden kidney damage
26 reports
- Weakness
Weakness
21 reports
- Loose stools
Loose stools
21 reports
- Long-term kidney problems
Long-term kidney problems
19 reports
- Low blood pressure
Low blood pressure
19 reports
- Swelling in the arms or legs
Swelling in the arms or legs
19 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 isradipine 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 isradipine sits
isradipine has more FDA adverse-event reports than 4% 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 isradipine; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 541 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
541
Reports Mentioning Death
61
11.3% of reports — not proof of cause
Hospitalization Reports
291
Top Indication
Hypertension
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | DRUG INTERACTION | 32 |
| 3 | DYSPNOEA | 31 |
| 4 | HYPERTENSION | 29 |
| 6 | ACUTE KIDNEY INJURY | 26 |
| 7 | NAUSEA | 26 |
| 8 | ASTHENIA | 20 |
| 9 | DIARRHOEA | 20 |
| 10 | CHRONIC KIDNEY DISEASE | 19 |
| 11 | HYPOTENSION | 19 |
| 12 | RENAL FAILURE | 19 |
| 13 | TUBULOINTERSTITIAL NEPHRITIS | 19 |
| 14 | OEDEMA PERIPHERAL | 18 |
| 15 | PYREXIA | 18 |
| 16 | VOMITING | 17 |
| 17 | DEATH | 16 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
If you are taking cimetidine, your doctor should watch you closely for side effects when you start isradipine. If you are taking rifampicin, isradipine may not work as well.
Known Drug Interactions
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: This medication does not affect the speed at which your body breaks down theophylline or clears it from your blood.
What to do: You can take these two medicines together without needing to change your theophylline dose, though close monitoring is always recommended.
Hydrochlorothiazide: A study in normal healthy volunteers has shown that concomitant administration of isradipine and hydrochlorothiazide does not result in altered pharmacokinetics of either drug. In a study in hypertensive patients, addition of isradipine to existing hydrochlorothiazide therapy did not result in any unexpected adverse effects, and isradipine had an additional antihypertensive effect.
Mechanism: These medicines work in different ways to lower blood pressure, which can lead to a stronger effect when taken together.
What to do: Your doctor may use this combination to better control your blood pressure, but you should report any dizziness or lightheadedness.
Propranolol: In a single dose study in normal volunteers, co-administration of propranolol had a small effect on the rate but no effect on the extent of isradipine bioavailability. Significant increases in AUC (27%) and C max (58%) and decreases in t max (23%) of propranolol were noted in this study. propranolol to healthy volunteers under steady-state conditions had no relevant effect on either drug's bioavailability.
Mechanism: Taking these drugs together may temporarily change how much medicine is in your blood, but this effect usually disappears after a few days of regular use.
What to do: Your doctor may monitor your heart rate and blood pressure more closely when you first start taking these two drugs together.
Warfarin: In a study in healthy volunteers, no clinically relevant pharmacokinetic or pharmacodynamic interaction between isradipine and racemic warfarin was seen when two single oral doses of warfarin (0.7 mg/kg body weight) were administered during 11 days of multiple-dose treatment with 5 mg b.i.d. Neither racemic warfarin nor isradipine binding to plasma proteins in vitro was altered by the addition of the other drug.
Mechanism: These two drugs do not appear to change how the body handles or responds to either medication.
What to do: No special changes are usually needed, but you should continue your regular blood tests for monitoring your blood thinner.
Digoxin: The concomitant administration of isradipine and digoxin in a single-dose pharmacokinetic study did not affect renal, nonrenal and total body clearance of digoxin.
Mechanism: Isradipine does not change how your body removes digoxin from your system.
What to do: You can usually take these together without changing your dose, but your doctor will continue to monitor your heart health.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What if I'm over 65?
Can I take this with other blood pressure medicines?
How long does it take for isradipine to work?
What should I avoid while taking isradipine?
Can I drink alcohol while taking isradipine?
What if I have liver problems?
Can isradipine cause constipation?
Will isradipine cure my high blood pressure?
Can I stop taking isradipine if my blood pressure is normal?
Does Isradipine interact with any other medications?
What are the common side effects of isradipine?
Does isradipine interact with other medications?
What drug class is isradipine?
Is isradipine safe during pregnancy?
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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
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for isradipine
The FDA label for isradipine (sold under brand names such as DynaCirc) classifies it as a prescription-only medication in the Calcium Channel Blocker class. Isradipine capsules are used to treat high blood pressure. Official labeling lists 6 commonly reported side effects, including Headache, Dizziness, Swelling in ankles or feet.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 541 voluntary reports. The database also lists 9 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 $2.52.
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, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
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).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 27, 2019
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 and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
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