diltiazem vs isradipine
PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.
Side-by-side comparison of diltiazem and isradipine. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Cardizem, Tiazac
DynaCirc
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.
Isradipine is a drug that helps lower high blood pressure. It belongs to a class of drugs called calcium channel blockers.
Diltiazem is used to treat high blood pressure. It can be used alone or with other blood pressure medicines. Diltiazem also helps manage chronic stable angina (chest pain) and angina caused by spasms in the heart's blood vessels.
Isradipine capsules are used to treat high blood pressure. You can take it alone or with a thiazide diuretic (water pill). It may take 2 to 4 weeks to see the full effect.
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.
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.
- • Swelling in your ankles or feet
- • Headache
- • Dizziness
- • Slow heart rate
- • Constipation
- • Headache
- • Dizziness
- • Swelling in ankles or feet
- • Feeling your heart beat rapidly or irregularly
- • Fatigue
- Dyspnoea 3,202
- Fatigue 2,638
- Nausea 2,372
- Pain 2,365
- Dizziness 2,091
- Drug Interaction 32
- Dyspnoea 31
- Hypertension 29
- Acute Kidney Injury 26
- Nausea 26
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.
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.
Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. It is not known if diltiazem will harm your unborn baby. Diltiazem passes into breast milk, so talk to your doctor about breastfeeding while taking this medicine.
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.
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How to Read This diltiazem vs isradipine Comparison
diltiazem is classified in the Calcium Channel Blocker drug class, while isradipine sits within the Calcium Channel Blocker class. Because both drugs share the same classification, they are often considered interchangeable in theory, but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, diltiazem has 12,668 submissions while isradipine has 144. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for diltiazem or isradipine.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.