This page presents data from the FDA Adverse Event Reporting System (FAERS) and the FDA-approved drug label. A report submitted to FAERS does not prove a drug caused the reported event. Always consult a healthcare provider about medications.

Metformin (metformin er 500 mg)

Last updated: June 20, 2026

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Metformin is the brand name for metformin er 500 mg. According to the FDA-approved label, & USAGE Metformin hydrochloride extended-release tablets, USP are indicated as an adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes mellitus. FAERS contains 294,221 submissions naming this drug from 2001 through 2026; the top three reactions cited are nausea, diarrhoea, and blood glucose increased.

Most-Reported Reactions

Counts of the reactions most often cited in FAERS submissions that named Metformin. Inclusion here does not establish causation - submitters describe what was observed, not what was confirmed. One submission can list several reactions, so the totals exceed the report count.

Patient Demographics

Patient sex and age across the FAERS submissions that named Metformin. Percentages here are computed only from submissions where these fields were filled in - many leave them blank.

By Sex

By Age Group

Severity Outcomes

Severity flags recorded across the 294,221 FAERS submissions that named Metformin. Each bar shows the count of those reports carrying that flag. A single case can carry more than one (a hospitalization that became life-threatening, for example), so these bars are independent rates - they don't sum to 100%. Inclusion of a case under any flag does not establish that the drug caused the outcome.

Submissions Per Quarter

Quarterly count of FAERS submissions that named Metformin. Ups and downs on this chart can track prescribing volume, news cycles, or shifts in how reports get filed, rather than the drug becoming safer or more dangerous.

From the FDA-Approved Label

Excerpts from the official FDA-approved prescribing information for Metformin. This is the authoritative source on indications, warnings, and known adverse reactions.

Indications

& USAGE Metformin hydrochloride extended-release tablets, USP are indicated as an adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes mellitus.

Warnings

LACTIC ACIDOSIS: Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension and resistant bradyarrhythmias. The onset of metformin associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Metformin associated lactic acidosis was characterized by elevated blood lactate levels(>5 mmol/Liter), anion gap acidosis (without evidenceof ketonuria or ketonemia), an increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL (see PRECAUTIONS ). Risk factors for metformin associated lactic acidosis include renal impairment, concamitent use of certain drugs (e.g carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, and hepatic impairment. Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided (see DOSAGE AND ADMINISTRATION , CONTRAINDICATIONS , AND PRECAUTIONS ). (continues in label)

Adverse Reactions (from label)

In A US double blind clinical study of metformin hydrochloride tablets in patients with type 2 diabetes, a total of 141 patients received metformin hydrochloride tablets therapy (up to 2550 mg per day) and 145 patients received placebo. Adverse reactions reported in greater than 5% of the metformin hydrochloride tablets patients, and that were more common in metformin hydrochloride tablets than placebo treated patients, are listed in Table 6. Table 6: Most Common Adverse Reactions (>5 Percent) in a Placebo-Controlled Clinical Study of Metformin Hydrochloride Tablets Monotherapy* Adverse Reaction Metformin Hydrochloride Tablets (n=141) Placebo (n=145) % of Patients Diarrhea 53.2 11.7 Nausea/Vomiting 25.5 8.3 Flatulence 12.1 5.5 Asthenia 9.2 5.5 Indigestion 7.1 4.1 Abdominal Discomfort 6.4 4.8 Headache 5.7 4.8 *Reactions that were more common in metformin hydrochloride tablets than placebo treated patients. Diarrhea led to discontinuation of study medication in 6% of patients treated with metformin hydrochloride tablets. Additionally, the following adverse reactions were reported in ≥1 - ≤5% of metformin hydrochloride tablets patients and myalgia, lightheaded, dyspnea, nail disorder,...

FDA label effective date: 2025-08-22

Disclaimer

AdverseEvent.ai is not affiliated with the FDA. Adverse-event counts come from the FDA Adverse Event Reporting System (FAERS). Drug labels come from the FDA drug label dataset. A report submitted to FAERS does not prove a drug caused the reported event — always consult a healthcare provider about medications. This site is for informational purposes only and is not medical advice.