Losartan and Hydrochlorothiazide side effects: what 11,544 FDA adverse event reports show
Drug class
Angiotensin ii receptor blocker (arb)
Label matched
Losartan (Losartan Potassium)
Who reports
11,544 reports · 65% serious · 697 with death outcome · 65% female
Used for
Losartan potassium tablet is an angiotensin II receptor blocker (ARB) indicated for: • Treatment of hypertension, to lower blood pressure in adults and children greater than 6 years old. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions.
What it is
Losartan potassium is an angiotensin II receptor blocker acting on the At 1 receptor subtype. Losartan potassium, a non-peptide molecule, is chemically described as 2-butyl-4-chloro-1-[ p -( o -1 H- tetrazol-5-ylphenyl)benzyl]imidazole-5-methanol monopotassium salt.
Boxed warning
FETAL TOXICITY When pregnancy is detected, discontinue losartan potassium tablets as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. [see Warnings and Precautions (5.1) ]. WARNING: FETAL TOXICITY See full prescribing information for complete boxed warning.
Causality screen of the 40 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 1,079 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Ocular procedural complication | 16 | 161.9 97.1–270.0ROR 162.1 · χ² 2,201 / p <1e-300 | 126.5 EB05 82.6 · IC025 +3.9 3/3 methods agree | Reporting / coding artifact | serious n=16 | no trial data cached |
| Disability assessment scale score increased | 12 | 72.9 40.9–129.7ROR 72.9 · χ² 750 / p 2e-165 | 63.3 EB05 38.6 · IC025 +3.2 3/3 methods agree | Lab value / disease marker | serious n=12 | no trial data cached |
| Colon adenoma | 16 | 29.6 18.1–48.5ROR 29.6 · χ² 407 / p 9e-91 | 28.2 EB05 18.4 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=16 | no trial data cached |
| Hypochloraemia | 13 | 20.5 11.8–35.3ROR 20.5 · χ² 219 / p 7e-50 | 19.5 EB05 11.7 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious n=13 | no trial data cached |
| Hyperparathyroidism secondary | 27 | 19.6 13.4–28.6ROR 19.6 · χ² 452 / p 1e-100 | 19.1 EB05 13.7 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=27 | no trial data cached |
| Dilatation atrial | 12 | 18.6 10.6–32.9ROR 18.7 · χ² 181 / p 1e-41 | 17.5 EB05 9.9 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Left atrial dilatation | 13 | 18.6 10.7–32.0ROR 18.6 · χ² 197 / p 6e-45 | 17.5 EB05 10.3 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=13 | no trial data cached |
| Chronic kidney disease-mineral and bone disorder | 10 | 17.0 9.1–31.7ROR 17.0 · χ² 134 / p 3e-31 | 15.4 EB05 7.8 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Nephrogenic anaemia | 43 | 16.9 12.5–22.7ROR 16.9 · χ² 620 / p 4e-137 | 16.5 EB05 12.7 · IC025 +3.3 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=43 | no trial data cached |
| Complex regional pain syndrome | 12 | 14.8 8.4–26.0ROR 14.8 · χ² 139 / p 2e-32 | 13.3 EB05 7.2 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Fine motor skill dysfunction | 22 | 14.0 9.2–21.2ROR 14.0 · χ² 250 / p 1e-56 | 13.3 EB05 8.8 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious n=21 · ♀ 100% (drug 65%) | no trial data cached |
| Ventricular hypertrophy | 19 | 13.7 8.7–21.5ROR 13.7 · χ² 210 / p 7e-48 | 12.9 EB05 8.2 · IC025 +2.6 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=19 | no trial data cached |
| Diabetes mellitus non-insulin-dependent | 11 | 13.7 7.5–24.7ROR 13.7 · χ² 116 / p 3e-27 | 11.9 EB05 6.2 · IC025 +2.1 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=11 | no trial data cached |
| Renal artery stenosis | 10 | 13.2 7.1–24.6ROR 13.2 · χ² 100 / p 7e-24 | 11.2 EB05 5.6 · IC025 +2.0 3/3 methods agree | Labeled — boxed warning exact term | serious n=10 | no trial data cached |
| Muscle fatigue | 30 | 13.0 9.1–18.6ROR 13.0 · χ² 317 / p 3e-71 | 12.4 EB05 8.9 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=27 · ♀ 85% (drug 65%) | no trial data cached |
| Blood pressure inadequately controlled | 40 | 12.1 8.8–16.4ROR 12.1 · χ² 392 / p 2e-87 | 11.6 EB05 8.7 · IC025 +2.9 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=30 | no trial data cached |
| Colonic polyp | 11 | 12.0 6.6–21.7ROR 12.0 · χ² 99 / p 1e-23 | 10.1 EB05 5.3 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| Osteosclerosis | 10 | 11.6 6.2–21.6ROR 11.6 · χ² 86 / p 1e-20 | 9.4 EB05 4.9 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious n=9 | no trial data cached |
| Intermittent claudication | 10 | 11.5 6.2–21.3ROR 11.5 · χ² 85 / p 2e-20 | 9.3 EB05 4.8 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Actinic keratosis | 16 | 11.2 6.8–18.3ROR 11.2 · χ² 138 / p 4e-32 | 9.9 EB05 6.0 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious n=16 | no trial data cached |
| Dilatation ventricular | 13 | 11.2 6.5–19.3ROR 11.2 · χ² 110 / p 6e-26 | 9.5 EB05 5.4 · IC025 +2.1 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=13 | no trial data cached |
| Diverticulum | 42 | 10.6 7.9–14.4ROR 10.7 · χ² 355 / p 1e-79 | 10.1 EB05 7.7 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious n=42 | no trial data cached |
| Aortic arteriosclerosis | 15 | 10.6 6.4–17.6ROR 10.6 · χ² 120 / p 3e-28 | 9.2 EB05 5.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious n=15 | no trial data cached |
| Ischaemic cardiomyopathy | 18 | 10.6 6.7–16.9ROR 10.6 · χ² 146 / p 5e-34 | 9.4 EB05 5.9 · IC025 +2.3 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=18 | no trial data cached |
| Neuropathy | 10 | 10.6 5.7–19.7ROR 10.6 · χ² 77 / p 9e-19 | 8.4 EB05 4.5 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious n=9 | no trial data cached |
| Essential hypertension | 15 | 10.6 6.4–17.6ROR 10.6 · χ² 120 / p 3e-28 | 9.1 EB05 5.5 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious n=11 | no trial data cached |
| Spondylolisthesis | 10 | 10.5 5.6–19.5ROR 10.5 · χ² 76 / p 1e-18 | 8.3 EB05 4.4 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Spinal column stenosis | 27 | 10.3 7.1–15.0ROR 10.3 · χ² 216 / p 3e-49 | 9.5 EB05 6.6 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=27 | no trial data cached |
| Monocyte count increased | 20 | 10.0 6.5–15.6ROR 10.0 · χ² 153 / p 2e-35 | 8.9 EB05 5.8 · IC025 +2.3 3/3 methods agree | Lab value / disease marker | serious n=20 | no trial data cached |
| Hypertensive heart disease | 10 | 9.7 5.2–18.0ROR 9.7 · χ² 69 / p 5e-17 | 7.6 EB05 4.1 · IC025 +1.7 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=10 | no trial data cached |
| Coronary artery disease | 162 | 9.7 8.3–11.3ROR 9.8 · χ² 1,249 / p 8e-274 | 9.5 EB05 8.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 | no trial data cached |
| Diverticulum intestinal | 23 | 9.6 6.4–14.5ROR 9.6 · χ² 169 / p 8e-39 | 8.7 EB05 5.9 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious n=23 · ♀ 86% (drug 65%) | no trial data cached |
| Carotid artery stenosis | 18 | 9.4 5.9–14.9ROR 9.4 · χ² 125 / p 2e-29 | 8.2 EB05 5.2 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious n=18 | no trial data cached |
| Blood creatinine decreased | 16 | 9.3 5.7–15.2ROR 9.3 · χ² 110 / p 5e-26 | 8.0 EB05 5.0 · IC025 +2.0 3/3 methods agree | Likely indication confounding term in indications | serious n=16 | no trial data cached |
| Blood chloride decreased | 13 | 9.1 5.3–15.7ROR 9.1 · χ² 86 / p 1e-20 | 7.5 EB05 4.4 · IC025 +1.9 3/3 methods agree | Lab value / disease marker | serious n=12 | no trial data cached |
| Recalled product administered | 44 | 9.1 6.8–12.2ROR 9.1 · χ² 308 / p 3e-69 | 8.6 EB05 6.6 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious n=10 · 100% consumer | no trial data cached |
| Haemorrhagic anaemia | 22 | 9.0 5.9–13.7ROR 9.0 · χ² 148 / p 3e-34 | 8.0 EB05 5.4 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious n=22 · 73% consumer | no trial data cached |
| Heart injury | 12 | 8.7 4.9–15.3ROR 8.7 · χ² 74 / p 5e-18 | 7.0 EB05 4.1 · IC025 +1.7 3/3 methods agree | Labeled (related wording) related wording | serious n=12 | no trial data cached |
| Hypovolaemia | 27 | 8.4 5.8–12.3ROR 8.4 · χ² 168 / p 8e-39 | 7.6 EB05 5.4 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious n=27 | no trial data cached |
| Renal failure chronic | 36 | 8.4 6.1–11.7ROR 8.4 · χ² 227 / p 1e-51 | 7.8 EB05 5.8 · IC025 +2.4 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 7.5 | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Nausea | 773 | 1.8 1.7–1.9ROR 1.8 · χ² 274 / p 9e-62 | 1.8 EB05 1.7 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 2.0 | no trial data cached |
| Drug ineffective (drug did not work) | 741 | 1.0 1.0–1.1ROR 1.0 · χ² 0 / p 0.276 | 1.0 EB05 1.0 · IC025 -0.1 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.1 | no trial data cached |
| Fatigue (tiredness) | 688 | 1.6 1.5–1.7ROR 1.6 · χ² 164 / p 8e-38 | 1.6 EB05 1.5 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.8 | no trial data cached |
| Dizziness | 588 | 2.1 2.0–2.3ROR 2.2 · χ² 367 / p 4e-82 | 2.1 EB05 2.0 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.2 | no trial data cached |
| Headache | 563 | 1.6 1.5–1.8ROR 1.7 · χ² 142 / p 5e-33 | 1.6 EB05 1.5 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.8 | no trial data cached |
| Diarrhoea (diarrhea) | 534 | 1.5 1.4–1.6ROR 1.5 · χ² 94 / p 2e-22 | 1.5 EB05 1.4 · IC025 +0.4 | Labeled adverse reaction exact term | serious PRR 1.4 | no trial data cached |
| Pain | 512 | 1.5 1.4–1.6ROR 1.5 · χ² 91 / p 8e-22 | 1.5 EB05 1.4 · IC025 +0.4 | Labeled adverse reaction exact term | serious PRR 1.7 | no trial data cached |
| Dyspnoea (shortness of breath) | 511 | 1.6 1.5–1.8ROR 1.7 · χ² 131 / p 1e-30 | 1.6 EB05 1.5 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.6 | no trial data cached |
| Arthralgia (joint pain) | 453 | 2.0 1.8–2.2ROR 2.0 · χ² 225 / p 3e-51 | 2.0 EB05 1.8 · IC025 +0.8 | Labeled adverse reaction exact term | serious PRR 2.3 | no trial data cached |
| Asthenia (weakness) | 450 | 2.2 2.0–2.4ROR 2.2 · χ² 289 / p 4e-65 | 2.2 EB05 2.0 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.1 | no trial data cached |
| Vomiting | 403 | 1.6 1.4–1.7ROR 1.6 · χ² 83 / p 5e-20 | 1.6 EB05 1.4 · IC025 +0.5 | Labeled adverse reaction exact term | serious PRR 1.6 | no trial data cached |
| Hypertension (high blood pressure) | 377 | 3.2 2.9–3.6ROR 3.3 · χ² 584 / p 2e-129 | 3.2 EB05 3.0 · IC025 +1.5 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 3.1 | no trial data cached |
| Blood pressure increased | 359 | 4.3 3.8–4.7ROR 4.4 · χ² 898 / p 1e-197 | 4.2 EB05 3.9 · IC025 +1.9 3/3 methods agree | Likely indication confounding term in indications | serious PRR 4.0 | no trial data cached |
| Malaise (feeling unwell) | 352 | 1.5 1.3–1.6ROR 1.5 · χ² 51 / p 6e-13 | 1.5 EB05 1.3 · IC025 +0.4 | Labeled adverse reaction exact term | serious PRR 1.5 | no trial data cached |
| Fall | 346 | 1.9 1.7–2.1ROR 1.9 · χ² 147 / p 5e-34 | 1.9 EB05 1.7 · IC025 +0.7 | Not in label — unassessed | serious PRR 1.7 | no trial data cached |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Hyperparathyroidism secondary — n=27, PRR 19.6
- Fine motor skill dysfunction — n=22, PRR 14.0
- Muscle fatigue — n=30, PRR 13.0
- Diverticulum — n=42, PRR 10.6
- Spinal column stenosis — n=27, PRR 10.3
- Coronary artery disease — n=162, PRR 9.7
- Diverticulum intestinal — n=23, PRR 9.6
- Haemorrhagic anaemia — n=22, PRR 9.0
- Hypovolaemia — n=27, PRR 8.4
✓ A hand-written Bradford Hill causality assessment exists for this drug: Losartan ↔ Renal failure.
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Losartan and Hydrochlorothiazide?
In FDA FAERS, the most frequently co-reported reaction terms for Losartan and Hydrochlorothiazide are nausea, fatigue, dizziness, headache, diarrhoea, pain. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Losartan and Hydrochlorothiazide have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: FETAL TOXICITY When pregnancy is detected, discontinue losartan potassium tablets as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. [see Warnings and Precautions (5.1) ]. WARNING: FETAL TOXICITY See full prescribing information for complete boxed warning.
Do FAERS signals prove that Losartan and Hydrochlorothiazide causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 9501dfaa-c8cf-46d6-8bec-936c4fd8fe03, effective 20260716; matched on
openfda.generic_name.exact:"LOSARTAN") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 1,119 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.