Losartan vs Valsartan: side effects in FDA adverse event reports
At a glance
| Losartan | Valsartan | |
|---|---|---|
| Drug class | – | Angiotensin 2 Receptor Blocker |
| Brand names | Losartan Potassium | – |
| FAERS reports | 173,627 | 104,469 |
| Serious | 63% | 76% |
| Death outcome | 12,522 | 9,543 |
| Boxed warning | Yes FETAL TOXICITY When pregnancy is detected, discontinue losartan potassium tablets as soon as possible. Drugs that act directly on the renin-angiotensin system c | Yes FETAL TOXICITY WARNING: FETAL TOXICITY • When pregnancy is detected, discontinue valsartan tablets as soon as possible. (5.1) • Drugs that act directly on the r |
Signals both drugs share
| Reaction | Losartan | Valsartan | Label screen (A / B) |
|---|---|---|---|
| Blood pressure inadequately controlled | 222 · PRR 4.5 | 795 · PRR 30.2 | Likely indication confounding / Labeled (related wording) |
| Infarction | 227 · PRR 4.1 | 332 · PRR 10.1 | Likely indication confounding / Labeled — boxed warning |
| Oligohydramnios | 100 · PRR 3.7 | 270 · PRR 17.5 | Labeled — boxed warning / Labeled — boxed warning |
| End stage renal disease | 1,263 · PRR 8.8 | 706 · PRR 8.0 | Likely indication confounding / Not in label — unassessed |
| Nephrogenic anaemia | 650 · PRR 19.4 | 433 · PRR 20.4 | Likely indication confounding / Not in label — unassessed |
| Hyperparathyroidism secondary | 364 · PRR 20.1 | 215 · PRR 18.5 | Not in label — unassessed / Not in label — unassessed |
| Rebound acid hypersecretion | 339 · PRR 14.9 | 135 · PRR 9.2 | Not in label — unassessed / Not in label — unassessed |
| Multi-organ disorder | 141 · PRR 9.2 | 144 · PRR 15.6 | Not in label — unassessed / Not in label — unassessed |
| Chronic kidney disease-mineral and bone disorder | 185 · PRR 24.9 | 84 · PRR 16.9 | Not in label — unassessed / Not in label — unassessed |
| Brash syndrome | 135 · PRR 13.2 | 73 · PRR 11.4 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Losartan
- Acute kidney injury — n=4,669, PRR 3.8 Labeled — boxed warning
- Chronic kidney disease — n=4,187, PRR 6.9 Labeled — boxed warning
- Renal injury — n=930, PRR 3.8 Labeled (related wording)
- Vasculitis — n=456, PRR 4.9 Labeled adverse reaction
- Tension headache — n=408, PRR 12.6 Labeled (related wording)
- Essential hypertension — n=96, PRR 4.6 Labeled adverse reaction
Labeled signals distinctive to Valsartan
- Foetal disorder — n=87, PRR 22.9 Labeled (related wording)
- Renal artery stenosis — n=82, PRR 12.6 Labeled adverse reaction
Common questions
Which has more reported side effects, Losartan or Valsartan?
Losartan has 173,627 FAERS reports and Valsartan 104,469. More reports does not mean more dangerous: volume follows how widely and how long a drug has been used, prescription vs over-the-counter status, and publicity. The seriousness share (63% vs 76%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Losartan and Valsartan share?
Both drugs carry disproportionality signals for blood pressure inadequately controlled, infarction, oligohydramnios, end stage renal disease, nephrogenic anaemia. Shared signals often reflect a shared drug class or the condition both are used for.
Is Losartan or Valsartan safer?
FAERS cannot answer that: it has no denominator and no comparator. Use this page to see which risks are already on each label and which signals are unlabeled, then check the prescribing information and your clinician for your situation.
Sources: openFDA FAERS pair statistics (OpenPV build 2026-09-14), FDA labels via openFDA, openFDA count queries for seriousness and deaths. Pair chosen because it is a commonly searched comparison. Generated 2026-10-08.