75/100 · Elevated
Manufactured by Santarus, Inc.
Metformin Hydrochloride Adverse Events: Lactic Acidosis and Kidney Injury Most Common
110,881 FDA adverse event reports analyzed
Last updated: 2026-05-12
METFORMIN HYDROCHLORIDE is a medication tracked in the FDA Adverse Event Reporting System (FAERS), manufactured by Santarus, Inc.. Based on analysis of 110,881 FDA adverse event reports, METFORMIN HYDROCHLORIDE has a safety score of 75 out of 100. This score indicates a relatively favorable safety profile, with fewer or less severe adverse events compared to many other tracked medications. The most commonly reported adverse reactions for METFORMIN HYDROCHLORIDE include LACTIC ACIDOSIS, DIARRHOEA, NAUSEA, ACUTE KIDNEY INJURY, FATIGUE. This page provides a comprehensive breakdown of reported side effects, safety signals, patient demographics, and AI-powered safety analysis for METFORMIN HYDROCHLORIDE.
Metformin Hydrochloride has a safety concern score of 75 out of 100, placing it in the elevated concern category based on analysis of FDA adverse event data. The FDA has received approximately 110,881 adverse event reports for this medication, which is primarily manufactured by Santarus, Inc..
The most commonly reported adverse events include Lactic Acidosis, Diarrhoea, Nausea. Of classified reports, 73.2% were designated as serious by the FDA, meaning they involved hospitalization, disability, or other significant medical outcomes. Lactic acidosis and acute kidney injury are the most serious adverse events reported.
Diarrhea and nausea are the most common gastrointestinal issues. Drug interactions and overuse are significant concerns.
Patients taking Metformin Hydrochloride should monitor for the commonly reported side effects and contact their healthcare provider if they experience any unusual symptoms. Metformin can cause lactic acidosis, especially in patients with renal impairment. It is contraindicated in patients with severe renal impairment or acute kidney injury. This analysis is based on voluntary FDA adverse event reports and should not replace professional medical advice.
Metformin Hydrochloride received a safety concern score of 75/100 (elevated concern). This is based on a 73.2% serious event ratio across 55,183 classified reports. The score accounts for 110,881 total adverse event reports and 100 distinct reaction types. This elevated score indicates a notable proportion of serious adverse events and warrants careful monitoring.
Adverse event reports by sex: Female: 27,734, Male: 22,455, Unknown: 117. The most frequently reported age groups are age 65 (1,247 reports), age 70 (1,175 reports), age 73 (1,094 reports). These demographics reflect reporting patterns and may not represent the full patient population.
Out of 55,183 classified reports for METFORMIN HYDROCHLORIDE:
The FDA classifies an adverse event as “serious” if it results in death, hospitalization, disability, congenital anomaly, or requires intervention to prevent permanent damage.
Demographics reflect voluntary FDA adverse event reporting patterns and may not represent the full patient population.
Metformin can cause lactic acidosis, especially in patients with renal impairment. It is contraindicated in patients with severe renal impairment or acute kidney injury.
If you are taking Metformin Hydrochloride, here are important things to know. The most commonly reported side effects include lactic acidosis, diarrhoea, nausea, acute kidney injury, fatigue. While many of these may be mild and temporary, you should contact your healthcare provider if any symptoms are severe or persistent. Monitor kidney function regularly, especially in elderly patients and those with pre-existing kidney conditions. Avoid metformin in patients with severe renal impairment or acute kidney injury. Report any unusual symptoms to your healthcare provider promptly. If you experience a serious adverse reaction, seek emergency medical attention immediately or call 911. You can report side effects to the FDA's MedWatch program at 1-800-FDA-1088.
The FDA continues to monitor metformin for safety, particularly for lactic acidosis and kidney injury. Regular monitoring of kidney function is recommended for patients on long-term metformin therapy.
The FDA has received approximately 110,881 adverse event reports associated with Metformin Hydrochloride. These reports come from healthcare professionals, consumers, and manufacturers through the FDA Adverse Event Reporting System (FAERS). Note that the number of reports does not directly indicate the frequency of side effects, as adverse events are voluntarily reported and may be underrepresented.
The most frequently reported adverse events for Metformin Hydrochloride include Lactic Acidosis, Diarrhoea, Nausea, Acute Kidney Injury, Fatigue. By volume, the top reported reactions are: Lactic Acidosis (4,272 reports), Diarrhoea (4,143 reports), Nausea (3,357 reports). These figures reflect FDA adverse event reports and may not represent the true incidence rate of these side effects in all patients taking Metformin Hydrochloride.
Out of 55,183 classified reports, 40,400 (73.2%) were classified as serious and 14,783 as non-serious. The FDA classifies an event as "serious" if it results in death, hospitalization, disability, or other medically significant outcomes. A higher serious-event ratio warrants closer attention but does not necessarily mean the drug is unsafe.
Adverse event reports for Metformin Hydrochloride break down by patient sex as follows: Female: 27,734, Male: 22,455, Unknown: 117. This distribution reflects reporting patterns rather than actual risk differences between groups. Reporting rates can be influenced by prescribing patterns, disease demographics, and reporting behavior.
The most frequently reported age groups for Metformin Hydrochloride adverse events are: age 65: 1,247 reports, age 70: 1,175 reports, age 73: 1,094 reports, age 72: 1,085 reports, age 66: 1,078 reports. Age-related reporting patterns can reflect both the demographics of the patient population and potential age-related susceptibility to certain side effects.
The primary manufacturer associated with Metformin Hydrochloride adverse event reports is Santarus, Inc.. Multiple manufacturers may produce generic versions of this drug. The manufacturer listed reflects the most frequently reported brand in FDA adverse event data.
Beyond the most common reactions, other reported adverse events for Metformin Hydrochloride include: Drug Ineffective, Vomiting, Dyspnoea, Headache, Off Label Use. Less common side effects can still be clinically significant. Patients should report any unusual symptoms to their healthcare provider.
You can report adverse events from Metformin Hydrochloride to the FDA through their MedWatch program at www.fda.gov/medwatch, by calling 1-800-FDA-1088, or by completing Form FDA 3500. Healthcare professionals, consumers, and manufacturers can all submit reports. Reporting helps the FDA monitor drug safety after approval.
Metformin Hydrochloride has a safety concern score of 75 out of 100 (elevated concern). This score is calculated from the ratio of serious to non-serious adverse events, the diversity of reported reactions, and the overall volume of reports relative to usage. Lactic acidosis and acute kidney injury are the most serious adverse events reported.
Key safety signals identified in Metformin Hydrochloride's adverse event data include: Lactic acidosis is reported in 3.8% of total reports.. Acute kidney injury is reported in 2.7% of total reports.. Drug interactions are reported in 0.86% of total reports.. These signals are derived from patterns in FDA reports and should be discussed with a healthcare provider for personalized assessment.
Metformin can cause lactic acidosis, especially in patients with renal impairment. It is contraindicated in patients with severe renal impairment or acute kidney injury. Always inform your healthcare provider about all medications, supplements, and over-the-counter drugs you are taking before starting Metformin Hydrochloride.
Monitor kidney function regularly, especially in elderly patients and those with pre-existing kidney conditions. Avoid metformin in patients with severe renal impairment or acute kidney injury. Report any unusual symptoms to your healthcare provider promptly.
Metformin Hydrochloride has 110,881 adverse event reports on file with the FDA. Diarrhea and nausea are the most common gastrointestinal issues. The volume of reports for Metformin Hydrochloride reflects both the drug's usage level and the vigilance of the reporting community.
The FDA continues to monitor metformin for safety, particularly for lactic acidosis and kidney injury. Regular monitoring of kidney function is recommended for patients on long-term metformin therapy. For the most current regulatory information, check the FDA's drug labeling database or consult your pharmacist.
Explore other medications manufactured by Santarus, Inc. and compare their safety profiles:
The following drugs share commonly reported adverse reactions with METFORMIN HYDROCHLORIDE:
Drugs related to METFORMIN HYDROCHLORIDE based on therapeutic use, drug class, or shared indications: