This grade answers one narrow question: how strong is the public evidence and safety record behind this drug, and how clean is its money trail and court record? It is not a verdict on whether the drug is right for you.
WARNING: 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 evidence of ketonuria or ketonemia), an increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL [ see Warnings and Precautions (5.1) ]. Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant 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, hepatic impairment, and mitochondrial diseases [see Warnings and Precautions (5.1) ] . Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are pr...
Warnings the FDA chose to announce publicly after approval, as opposed to quiet label edits. Class-wide items name the drug's class, not this drug specifically.
Listed on the WHO Model List of Essential Medicines: a global expert panel judged it among the medicines a health system should always have, on evidence of value, not marketing.
Metformin hydrochloride tablets are indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. Metformin hydrochloride tablets is a biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. (1)
Metformin hydrochloride tablets are contraindicated in patients with: Severe renal impairment (eGFR below 30 mL/min/1.73 m 2 ) [see Warnings and Precautions (5.1) ]. Hypersensitivity to metformin. Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Severe renal impairment (eGFR below 30 mL/min/1.73 m 2 ) (4 , 5.1) Hypersensitivity to metformin (4) Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. (4)
Lactic Acidosis: See boxed warning. (5.1) Vitamin B 12 Deficiency: Metformin may lower vitamin B 12 levels. Measure hematological parameters annually and vitamin B 12 at 2 to 3 year intervals and manage any abnormalities. (5.2) Hypoglycemia with Concomitant Use with Insulin and Insulin Secretagogues: Increased risk of hypoglycemia when used in combination with insulin and/or an insulin secretagogue. Lower dose of insulin or insulin secretagogue may be required (5.3) 5.1 Lactic Acidosis There have been postmarketing cases of metformin-associated lactic acidosis, including fatal cases. These cases had a subtle onset and were accompanied by nonspecific symptoms such as malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence; however, hypotension and resistant bradyarrhythmias have occurred with severe acidosis. Metformin-associated lactic acidosis was characterized by elevated blood lactate concentrations (>5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), and an increased lactate: pyruvate ratio; metformin plasma levels were generally >5 mcg/mL. Metformin decreases liver uptake of lactate increasing lactate blood levels which may inc...
The following adverse reactions are also discussed elsewhere in the labeling: Lactic Acidosis [see Boxed Warning and Warnings and Precautions (5.1) ] Vitamin B 12 Deficiency [see Warnings and Precautions (5.2) ] Hypoglycemia [see Warnings and Precautions (5.3) ] For metformin hydrochloride tablets, the most common adverse reactions (>5.0%) are diarrhea, nausea/vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Studies Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a U.S. clinical trial of metformin hydrochloride in patients with type 2 diabetes mellitus, a total of 141 patients received metformin hydrochloride up to 2550 mg per day. Adverse reactions reported in greater than 5% of metformin hydrochloride treated patients and that were more common than in placebo-trea...
Boxed Warning 04/2026
Source: FDA SPL label for Metformin Hydrochloride (REMEDYREPACK INC.), effective 20260821. Full label on DailyMed.
These are counts of reports people filed, not rates of harm. Anyone can file one, and nobody checks whether the drug was the cause. Millions of doses are taken for every report sent, so the useful part is how this drug compares with the average across all drugs.
| 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | 2026 |
|---|---|---|---|---|---|---|---|
| 36,965 | 34,532 | 28,347 | 26,107 | 26,058 | 24,980 | 25,346 | 12,315 |
1,797 reports blaming this drug for every million Medicare prescriptions filled, which is 0.6× the typical drug on this site. (61,770 reports in 2024–2026, against 34,375,334 Medicare fills in one year. This is the one number here that accounts for how many people take the drug.)
Source: the FDA's Adverse Event Reporting System (FAERS). Reports are voluntary and unverified. Drugs that are prescribed a lot, in the news, or in lawsuits attract more reports, so the percentages are compared with the whole database to correct for that partly, not fully.
| Date | Class | Firm | Reason |
|---|---|---|---|
| 02/2025 | Class II | A-S Medication Solutions LLC | Presence of Foreign Tablets/Capsules. |
| 12/2021 | Class II | VIONA PHARMACEUTICALS INC | CGMP Deviations- Detection of N-Nitrosodimethylamine (NDMA) levels in excess of the Acceptable Daily Intake Limit. |
| 06/2021 | Class II | VIONA PHARMACEUTICALS INC | CGMP Deviations: Detection of N-Nitrosodimethylamine (NDMA) levels in excess of the Acceptable Daily Intake Limit. |
| 05/2021 | Class II | SUN PHARMACEUTICAL INDUSTRIES INC | Presence of foreign substance: identified as activated carbon. |
| 03/2021 | Class III | SUN PHARMACEUTICAL INDUSTRIES INC | Failed Moisture Limits: Out of specification for water content |
| 10/2020 | Class II | Direct Rx | CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level (per manufacturer) |
| 10/2020 | Class II | PD-Rx Pharmaceuticals, Inc. | CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level (per manufacturer) |
| 10/2020 | Class II | PD-Rx Pharmaceuticals, Inc. | CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level (per manufacturer) |
| 10/2020 | Class II | Marksans Pharma Limited | CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level |
| 10/2020 | Class II | Marksans Pharma Limited | CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level |
| 08/2020 | Class II | BAYSHORE PHARMACEUTICALS | CGMP Deviations |
| 08/2020 | Class II | BAYSHORE PHARMACEUTICALS | CGMP Deviations |
Class I = reasonable probability of serious harm. Class II = temporary or reversible harm. Class III = unlikely to harm. Most generic recalls are manufacturing or labeling defects for one lot, not a verdict on the molecule.
Counts measure how much evidence exists and how transparent it is, not how big the benefit is. For that, ask your prescriber: if 100 people like me took this, how many would get better because of it, and how many would be harmed? (Doctors call these the "number needed to treat" and "number needed to harm.") It differs by condition and is the number drug ads leave out. Sources: PubMed, ClinicalTrials.gov.
In 2024, drug companies reported $0 in payments to US physicians and hospitals tied to this drug across 0 transactions.
No pending federal MDL names this drug or its brands.
Not named in any federal pharmaceutical settlement of $100M or more on record.
Sources: CMS Open Payments (Sunshine Act); Judicial Panel on Multidistrict Litigation pending docket list; DOJ settlements as tabulated on Wikipedia with links to the primary record. State-court and individual suits are not included.
| Product | Fills | $/fill |
|---|---|---|
| Metformin HCl | 23,961,097 | $8 |
| Metformin HCl ER | 10,256,666 | $10 |
| Metformin ER Gastric | 83,001 | $1,035 |
| Metformin ER Osmotic | 71,458 | $186 |
| Glumetza | 3,112 | $6,364 |
Same ATC pharmacological class, graded ones first, best grade at the top. Being in the same class does not make them interchangeable for your condition; it makes them worth asking about.