irbesartan vs losartan
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 irbesartan and losartan. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
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Irbesartan is a medicine that lowers blood pressure. It belongs to a class of drugs called angiotensin II receptor blockers (ARBs).
Losartan is a medicine that lowers blood pressure. It can also help prevent strokes in some people with high blood pressure and an enlarged heart.
Irbesartan is used to treat high blood pressure (hypertension). Lowering blood pressure reduces the risk of strokes and heart attacks. It is also used to treat kidney problems caused by diabetes in people with high blood pressure.
Losartan is used to treat high blood pressure in adults and children over 6 years old. Lowering blood pressure reduces the risk of strokes and heart attacks. It is also used to treat kidney problems in people with type 2 diabetes and high blood pressure. Losartan can also reduce the risk of stroke in patients with high blood pressure and an enlarged left ventricle of the heart.
Irbesartan blocks a substance in your body that tightens blood vessels. This helps blood vessels relax and widens them, which lowers blood pressure. It also helps protect the kidneys in people with diabetes.
Losartan blocks a substance in your body that tightens blood vessels. This helps blood vessels relax, which lowers blood pressure. It also helps the kidneys work better in people with diabetes.
- • Diarrhea
- • Heartburn
- • Tiredness
- • Increased potassium levels
- • Dizziness
- • Dizziness
- • Upper respiratory infection
- • Nasal congestion
- • Back pain
- Fatigue 2,460
- Nausea 2,420
- Diarrhoea 2,261
- Acute Kidney Injury 2,054
- Dizziness 1,985
- Fatigue 11,852
- Diarrhoea 9,870
- Nausea 9,207
- Dyspnoea 8,439
- Dizziness 7,999
Irbesartan can harm your unborn baby. If you are pregnant or plan to become pregnant, tell your doctor right away. Stop taking irbesartan as soon as you know you are pregnant.
Losartan can harm your unborn baby, even causing death. If you are pregnant or plan to become pregnant, tell your doctor right away. Stop taking losartan as soon as you know you are pregnant.
Irbesartan can cause serious harm or death to an unborn baby. Do not take this medicine if you are pregnant. Talk to your doctor if you are breastfeeding, as this medication may not be safe for your baby.
Do not take losartan if you are pregnant. It can cause serious harm or death to the developing fetus. If you are breastfeeding, talk to your doctor about whether losartan is right for you.
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How to Read This irbesartan vs losartan Comparison
irbesartan is classified in the Angiotensin II Receptor Blocker (ARB) drug class, while losartan sits within the Angiotensin II Receptor Blocker (ARB) 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, irbesartan has 11,180 submissions while losartan has 47,367. 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 irbesartan or losartan.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.