Metformin vs Metformin Er 500: side effects in FDA adverse event reports
At a glance
| Metformin | Metformin Er 500 | |
|---|---|---|
| Drug class | – | – |
| Brand names | Metformin Hydrochloride | Metformin |
| FAERS reports | 354,745 | 299,016 |
| Serious | 69% | 68% |
| Death outcome | 29,950 | 24,489 |
| Boxed warning | Yes LACTIC ACIDOSIS Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Th | Yes LACTIC ACIDOSIS Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Th |
Signals both drugs share
| Reaction | Metformin | Metformin Er 500 | Label screen (A / B) |
|---|---|---|---|
| Acute kidney injury | 17,231 · PRR 7.4 | 14,181 · PRR 7.1 | Labeled — boxed warning / Labeled — boxed warning |
| Lactic acidosis | 17,141 · PRR 67.6 | 12,763 · PRR 46.0 | Labeled — boxed warning / Labeled — boxed warning |
| Hypoglycaemia | 7,287 · PRR 10.3 | 5,729 · PRR 9.3 | Labeled — boxed warning / Labeled — boxed warning |
| Metabolic acidosis | 6,200 · PRR 14.2 | 4,822 · PRR 12.4 | Labeled adverse reaction / Labeled adverse reaction |
| Diabetic ketoacidosis | 4,053 · PRR 11.9 | 3,568 · PRR 12.1 | Labeled adverse reaction / Labeled adverse reaction |
| Diabetes mellitus inadequate control | 2,895 · PRR 11.4 | 2,387 · PRR 10.8 | Labeled (related wording) / Labeled (related wording) |
| Euglycaemic diabetic ketoacidosis | 1,754 · PRR 46.1 | 1,378 · PRR 36.8 | Labeled (related wording) / Labeled (related wording) |
| Ketoacidosis | 1,347 · PRR 12.8 | 1,158 · PRR 12.7 | Labeled adverse reaction / Labeled adverse reaction |
| Vitamin b12 deficiency | 630 · PRR 10.8 | 482 · PRR 9.4 | Labeled (related wording) / Labeled (related wording) |
| Diabetic metabolic decompensation | 469 · PRR 29.9 | 368 · PRR 25.1 | Labeled (related wording) / Labeled (related wording) |
| Anion gap increased | 243 · PRR 12.9 | 212 · PRR 13.0 | Labeled (related wording) / Labeled (related wording) |
| Impaired gastric emptying | 1,751 · PRR 9.3 | 1,668 · PRR 10.4 | Not in label — unassessed / Not in label — unassessed |
| Hyperlactacidaemia | 804 · PRR 25.6 | 633 · PRR 21.9 | Not in label — unassessed / Not in label — unassessed |
| Diabetic neuropathy | 670 · PRR 9.0 | 575 · PRR 9.0 | Likely indication confounding / Likely indication confounding |
| Suspected suicide | 578 · PRR 8.0 | 578 · PRR 9.5 | Not in label — unassessed / Not in label — unassessed |
| Nephrogenic anaemia | 536 · PRR 7.5 | 503 · PRR 8.3 | Not in label — unassessed / Not in label — unassessed |
| Hypoglycaemic coma | 508 · PRR 12.4 | 308 · PRR 8.2 | Not in label — unassessed / Not in label — unassessed |
| Gastrointestinal hypomotility | 384 · PRR 12.1 | 380 · PRR 14.2 | Not in label — unassessed / Not in label — unassessed |
| Diabetic retinopathy | 389 · PRR 7.5 | 327 · PRR 7.4 | Likely indication confounding / Likely indication confounding |
| Personality disorder | 345 · PRR 8.8 | 253 · PRR 7.3 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Metformin
- None stood out among the strongest labeled signals.
Labeled signals distinctive to Metformin Er 500
- None stood out among the strongest labeled signals.
Common questions
Which has more reported side effects, Metformin or Metformin Er 500?
Metformin has 354,745 FAERS reports and Metformin Er 500 299,016. 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 (69% vs 68%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Metformin and Metformin Er 500 share?
Both drugs carry disproportionality signals for acute kidney injury, lactic acidosis, hypoglycaemia, metabolic acidosis, diabetic ketoacidosis. Shared signals often reflect a shared drug class or the condition both are used for.
Is Metformin or Metformin Er 500 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.