Metformin
294,215 adverse event reports submitted to the FDA (2001–2026)
Top Reported Adverse Events
The most frequently reported events in association with Metformin in the FAERS database. These are events reported by patients taking this medication, not necessarily caused by it. A single report may include multiple events.
Show these terms with plain-language definitions
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Nausea 19,251 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Diarrhoea 18,463 reports
Loose or watery bowel movements, often frequent. Also spelled diarrhea in American English.
Full definition in the glossary → See all drugs reporting this event →Blood Glucose Increased 16,869 reports
A blood test result showing a higher than normal blood sugar level.
Full definition in the glossary →Drug Ineffective 16,047 reports
A report that the medication did not work as expected for the person taking it. This is a reporting category, not a sign the drug is defective. It simply means someone felt it was not helping their condition.
Full definition in the glossary →Fatigue 14,784 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Acute Kidney Injury 13,860 reports
A sudden drop in how well the kidneys are working. It is often temporary and can have many causes.
Full definition in the glossary →Vomiting 12,743 reports
Throwing up the contents of the stomach.
Full definition in the glossary → See all drugs reporting this event →- Lactic Acidosis 12,342 reports
Off Label Use 11,685 reports
Using a medication for a condition or in a way that the FDA has not officially approved. This is common and often legal, and a report of it does not mean something went wrong. Doctors sometimes prescribe drugs off label based on their judgment.
Full definition in the glossary →Dyspnoea 11,443 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Weight Decreased 10,768 reports
Dizziness 10,478 reports
A feeling of being lightheaded, unsteady, or like the room is spinning.
Full definition in the glossary → See all drugs reporting this event →Headache 10,143 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →Pain 9,996 reports
A general report of physical discomfort, used when no more specific location is given.
Full definition in the glossary →Malaise 8,904 reports
A general feeling of being unwell or uncomfortable, without a specific symptom.
Full definition in the glossary →
Ranked by frequency of reports, not severity. The most-reported event is not necessarily the most dangerous or the most common in patients taking this drug.
Who Is Reporting
Demographics of patients in FAERS reports that included this information. Not all reports include patient demographics.
By Sex
View reporter sex data as a table
| Sex | Reports |
|---|---|
| Female | 145,059 |
| Male | 125,231 |
| Unknown | 942 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 2,599 |
| 18-34 | 6,699 |
| 35-49 | 23,031 |
| 50-64 | 71,726 |
| 65-74 | 60,036 |
| 75+ | 41,177 |
This shows who filed reports, reflecting who takes this drug and who tends to report, not who is at greatest risk.
Reported Outcomes
Outcomes recorded in FAERS reports that included Metformin. A single report may involve multiple reactions, each with a different outcome. These categories are defined by FDA reporting guidelines, not by PillSignal.
View outcome data as a table
| Outcome | Reports |
|---|---|
| Other Serious | 125,029 |
| Hospitalization | 103,659 |
| Non-Serious | 94,299 |
| Death | 23,981 |
| Life-Threatening | 17,688 |
| Disability | 8,112 |
Serious outcomes are far more likely to be reported than mild ones, so this overstates how often outcomes are serious. A recorded death does not mean the drug caused it.
Report Volume Over Time
Number of FAERS reports received per quarter for Metformin. Changes in volume may reflect shifts in prescribing rates, media attention, or reporting behavior, not changes in the medication's safety profile.
View report trend as a table
| Year | Reports |
|---|---|
| 2001 | 1 |
| 2004 | 294 |
| 2005 | 1,281 |
| 2006 | 3,216 |
| 2007 | 706 |
| 2008 | 751 |
| 2009 | 1,751 |
| 2010 | 4,182 |
| 2011 | 3,169 |
| 2012 | 5,092 |
| 2013 | 11,346 |
| 2014 | 13,906 |
| 2015 | 24,012 |
| 2016 | 23,903 |
| 2017 | 23,222 |
| 2018 | 26,604 |
| 2019 | 27,563 |
| 2020 | 25,797 |
| 2021 | 21,185 |
| 2022 | 18,908 |
| 2023 | 18,837 |
| 2024 | 17,165 |
| 2025 | 17,348 |
| 2026 (partial) | 3,976 |
The steep increase around 2004 reflects the FDA's move to electronic submission, not a change in this drug's safety. Trends track reporting volume, not risk.
Medications commonly reported with Metformin
In FDA adverse event reports that mention Metformin, these medications appeared most often in the same report.
- Aspirin (38,280 reports)
- Lisinopril (34,594 reports)
- Omeprazole (29,204 reports)
- Insulin Glargine (28,447 reports)
- Furosemide (27,402 reports)
This reflects co-occurrence in submitted reports, not evidence of drug interaction or combined risk. People often report several medications taken for the same condition or for unrelated reasons. Talk to a doctor or pharmacist about your specific medications.
Related Drugs
Other medications with similar adverse event profiles in FDA FAERS reports.
Data Source
This data is sourced from the FDA's Adverse Event Monitoring System (AEMS), formerly FAERS, via the OpenFDA API. PillSignal is not affiliated with the FDA.
View this data on the FDA website →Data last updated: June 2026