metformin Side Effects
Also known as: Glucophage, Fortamet, Glumetza
Analysis of 342,023 adverse event reports submitted to the FDA from 2001 to 2025.
Total Reports
342,023
Death-Related
28,446
8.3% of reports
Hospitalizations
122,330
35.8% of reports
Top Indication
Product Used For Unknown Indication
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 28,446 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 7,610 |
| COMPLETED SUICIDE | 3,248 |
| LACTIC ACIDOSIS | 2,953 |
| TOXICITY TO VARIOUS AGENTS | 2,356 |
| ACUTE KIDNEY INJURY | 1,891 |
| CARDIAC ARREST | 1,343 |
| PNEUMONIA | 1,269 |
| DYSPNOEA | 1,235 |
| DIARRHOEA | 1,127 |
| OFF LABEL USE | 1,069 |
| METABOLIC ACIDOSIS | 1,041 |
| HYPOTENSION | 988 |
| RENAL FAILURE | 982 |
| VOMITING | 929 |
| NAUSEA | 915 |
| ASTHENIA | 872 |
| FATIGUE | 810 |
| FALL | 804 |
| SEPSIS | 792 |
| MULTIPLE ORGAN DYSFUNCTION SYNDROME | 772 |
Reactions in Hospitalization Reports
Top reactions in 122,330 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| ACUTE KIDNEY INJURY | 12,194 |
| LACTIC ACIDOSIS | 12,072 |
| DIARRHOEA | 7,796 |
| VOMITING | 7,587 |
| NAUSEA | 7,547 |
| DYSPNOEA | 7,249 |
| FALL | 5,943 |
| PNEUMONIA | 5,755 |
| FATIGUE | 5,432 |
| ASTHENIA | 5,244 |
| HYPOTENSION | 4,816 |
| METABOLIC ACIDOSIS | 4,785 |
| TOXICITY TO VARIOUS AGENTS | 4,778 |
| OFF LABEL USE | 4,405 |
| MALAISE | 4,327 |
| PAIN | 4,274 |
| HYPOGLYCAEMIA | 4,232 |
| DIZZINESS | 4,186 |
| DEHYDRATION | 4,129 |
| PYREXIA | 3,864 |
Nearby — Related Medications
What the FAERS Data Reveals About metformin Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 342,023 voluntary reports linked to metformin and its brand equivalents (Glucophage, Fortamet, Glumetza), spanning 2001 through 2025. Of those, 28,446 (8.3%) listed death as an outcome and 122,330 (35.8%) involved hospitalization. The most common indication reported alongside adverse events was Product Used For Unknown Indication.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 54% were female and 46% male; age distribution skews toward 45-64, with 93,985 reports in that bracket. The single most reported reaction is nausea with 21,946 submissions, followed by diarrhoea and blood glucose increased.
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice — speak with a licensed clinician about any side-effect concerns.
Read our methodology — how this data is sourced, computed, and verified.