Losartan vs Telmisartan: side effects in FDA adverse event reports
At a glance
| Losartan | Telmisartan | |
|---|---|---|
| Drug class | – | Angiotensin 2 Receptor Blocker |
| Brand names | Losartan Potassium | – |
| FAERS reports | 173,627 | 17,738 |
| Serious | 63% | 87% |
| Death outcome | 12,522 | 1,706 |
| 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 When pregnancy is detected, discontinue telmisartan as soon as possible [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1) |
Signals both drugs share
| Reaction | Losartan | Telmisartan | Label screen (A / B) |
|---|---|---|---|
| Arterial occlusive disease | 241 · PRR 3.8 | 196 · PRR 30.0 | Not in label — unassessed / Likely indication confounding |
| Brash syndrome | 135 · PRR 13.2 | 43 · PRR 38.7 | 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)
- Oligohydramnios — n=100, PRR 3.7 Labeled — boxed warning
- Essential hypertension — n=96, PRR 4.6 Labeled adverse reaction
Labeled signals distinctive to Telmisartan
- Urinary tract disorder — n=231, PRR 63.9 Labeled (related wording)
Common questions
Which has more reported side effects, Losartan or Telmisartan?
Losartan has 173,627 FAERS reports and Telmisartan 17,738. 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 87%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Losartan and Telmisartan share?
Both drugs carry disproportionality signals for arterial occlusive disease, brash syndrome. Shared signals often reflect a shared drug class or the condition both are used for.
Is Losartan or Telmisartan 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.