Furosemide vs Spironolactone: side effects in FDA adverse event reports
At a glance
| Furosemide | Spironolactone | |
|---|---|---|
| Drug class | Loop Diuretic | Aldosterone Antagonist |
| Brand names | – | – |
| FAERS reports | 398,182 | 139,599 |
| Serious | 81% | 78% |
| Death outcome | 61,850 | 18,066 |
| Boxed warning | No | No |
Signals both drugs share
| Reaction | Furosemide | Spironolactone | Label screen (A / B) |
|---|---|---|---|
| Hyperkalaemia | 5,819 · PRR 10.4 | 5,027 · PRR 25.1 | Not in label — unassessed / Labeled adverse reaction |
| Right ventricular failure | 1,267 · PRR 11.3 | 789 · PRR 18.8 | Not in label — unassessed / Not in label — unassessed |
| Nephrogenic anaemia | 1,661 · PRR 28.7 | 357 · PRR 12.3 | Likely indication confounding / Likely indication confounding |
| Cardiac failure chronic | 996 · PRR 15.8 | 585 · PRR 23.8 | Not in label — unassessed / Not in label — unassessed |
| Cardiac failure acute | 952 · PRR 8.6 | 445 · PRR 10.7 | Not in label — unassessed / Not in label — unassessed |
| Orthopnoea | 751 · PRR 15.9 | 384 · PRR 20.4 | Not in label — unassessed / Not in label — unassessed |
| Hyperparathyroidism secondary | 895 · PRR 28.4 | 177 · PRR 11.2 | Not in label — unassessed / Likely indication confounding |
| Hypervolaemia | 656 · PRR 8.2 | 325 · PRR 10.8 | Not in label — unassessed / Not in label — unassessed |
| Ischaemic cardiomyopathy | 584 · PRR 12.0 | 294 · PRR 15.7 | Not in label — unassessed / Likely indication confounding |
| Congestive cardiomyopathy | 536 · PRR 7.5 | 341 · PRR 13.1 | Not in label — unassessed / Likely indication confounding |
| Bundle branch block left | 548 · PRR 7.6 | 305 · PRR 11.5 | Not in label — unassessed / Not in label — unassessed |
| Left ventricular failure | 493 · PRR 8.7 | 226 · PRR 10.6 | Not in label — unassessed / Not in label — unassessed |
| Left atrial dilatation | 264 · PRR 13.4 | 107 · PRR 13.6 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Furosemide
- End stage renal disease — n=3,380, PRR 11.6 Labeled (related wording)
- Orthostatic hypotension — n=2,320, PRR 7.9 Labeled adverse reaction
- Metabolic alkalosis — n=428, PRR 19.0 Labeled (related wording)
Labeled signals distinctive to Spironolactone
- None stood out among the strongest labeled signals.
Common questions
Which has more reported side effects, Furosemide or Spironolactone?
Furosemide has 398,182 FAERS reports and Spironolactone 139,599. 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 (81% vs 78%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Furosemide and Spironolactone share?
Both drugs carry disproportionality signals for hyperkalaemia, right ventricular failure, nephrogenic anaemia, cardiac failure chronic, cardiac failure acute. Shared signals often reflect a shared drug class or the condition both are used for.
Is Furosemide or Spironolactone 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.