Prescription medication · Biguanide
metformin
Also sold as Glucophage, Fortamet, Glumetza.
Data updated 2026-05-15
- 342,023
- FDA reportsHeavily reported
- 27
- InteractionsSeveral interactions
- 11
- Recall records
What the data shows
metformin (Glucophage) is a prescription Biguanide, in the top 5% of tracked drugs by FAERS report volume (342,023 FDA reports), with 27 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.64/unit
Generic Available
Yes (52 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Information not available.
Common side effects
Diarrhea, Upper respiratory tract infection (like a cold), Headache
Key warnings
No specific warnings noted. Always follow your prescriber's instructions.
Side Effects (from patient reports)
Based on 342,023 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for metformin, by number of reports
- Feeling sick to your stomach
Feeling sick to your stomach
21,946 reports
- Loose or watery stools
Loose or watery stools
21,887 reports
- High blood sugar
High blood sugar
18,329 reports
- Feeling tired
Feeling tired
17,252 reports
- Sudden kidney damage
Sudden kidney damage
16,440 reports
- Build-up of lactic acid in the blood
Build-up of lactic acid in the blood
16,154 reports
- Throwing up
Throwing up
14,692 reports
- Difficulty breathing
Difficulty breathing
13,511 reports
- Feeling lightheaded
Feeling lightheaded
12,132 reports
- Weight loss
Weight loss
11,985 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for metformin each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where metformin sits
metformin has more FDA adverse-event reports than 98% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is metformin; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 342,023 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2001–2025.
Total Reports
342,023
Reports Mentioning Death
28,446
8.3% of reports — not proof of cause
Hospitalization Reports
122,330
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NAUSEA | 21,946 |
| 2 | DIARRHOEA | 21,884 |
| 3 | BLOOD GLUCOSE INCREASED | 18,328 |
| 5 | FATIGUE | 17,252 |
| 6 | ACUTE KIDNEY INJURY | 16,440 |
| 7 | LACTIC ACIDOSIS | 16,154 |
| 8 | VOMITING | 14,690 |
| 9 | DYSPNOEA | 13,513 |
| 11 | DIZZINESS | 12,131 |
| 12 | WEIGHT DECREASED | 11,985 |
| 13 | HEADACHE | 11,890 |
| 14 | PAIN | 11,567 |
| 15 | ASTHENIA | 10,467 |
| 16 | MALAISE | 10,353 |
| 17 | FALL | 9,374 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Known Drug Interactions
Metformin ↑ Metformin Refer to the prescribing information of metformin for assessing the benefit and risk of concomitant use of BIKTARVY and metformin.
Mechanism: This HIV medication can increase the amount of metformin that stays in your blood. This happens because the medicine interferes with how metformin is cleared from your system.
What to do: Your doctor should watch you closely for metformin side effects and may need to lower your metformin dose.
7.2 Potential for DOVATO to Affect Other Drugs Dolutegravir, a component of DOVATO, inhibits the renal organic cation transporters (OCT)2 and multidrug and toxin extrusion transporter (MATE)1; thus, it may increase plasma concentrations of drugs eliminated via OCT2 or MATE1 such as dofetilide, dalfampridine, and metformin [see Contraindications ( 4 ), Drug Interactions ( 7.4 ), Clinical Pharmacology ( 12.3 )]. Antidiabetic: Metformin a ↑Metformin Refer to the prescribing information for metformin for assessing the benefit and risk of concomitant use of DOVATO and metformin.
Mechanism: Dolutegravir blocks the proteins that help your kidneys remove metformin, which can lead to higher levels of metformin in your blood.
What to do: Talk to your doctor about the risks of this combination, as they may need to adjust your metformin treatment.
Drugs that Reduce Metformin Clearance Clinical Impact Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2] / multidrug and toxin extrusion [MATE] inhibitors such as ranolazine, vandetanib, dolutegravir, and cimetidine) could increase systemic exposure to metformin and may increase the risk for lactic acidosis [see Clinical Pharmacology (12.3) ] . Alcohol Clinical Impact Alcohol is known to potentiate the effect of metformin on lactate metabolism. ( 7 ) Drugs that...
Mechanism: Using these medicines together can increase the risk of a dangerous buildup of lactic acid in the blood. This risk is higher when other factors, such as alcohol, change how the body handles metformin.
What to do: Your doctor should monitor you for signs of acid buildup and may need to adjust your treatment plan.
Drugs that Reduce Metformin Clearance Clinical Impact Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2] / multidrug and toxin extrusion [MATE] inhibitors such as ranolazine, vandetanib, dolutegravir, and cimetidine) could increase systemic exposure to metformin and may increase the risk for lactic acidosis [see Clinical Pharmacology (12.3) ] . Alcohol Clinical Impact Alcohol is known to potentiate the effect of metformin on lactate metabolism. ( 7 ) Drugs that...
Mechanism: Taking these medications together can cause metformin to build up in your blood because the kidneys cannot remove it as quickly. This increase can lead to a dangerous condition where too much acid builds up in your blood.
What to do: Your doctor should monitor your kidney function and may need to adjust your medication doses.
7 DRUG INTERACTIONS Table 3: Clinically Significant Drug Interactions with SEGLUROMET Carbonic Anhydrase Inhibitors Clinical Impact: The risk of lactic acidosis may increase due to concomitant use of Topiramate or other carbonic anhydrase inhibitors (e.g., zonisamide, acetazolamide or dichlorphenamide) with metformin. Drugs that Reduce Metformin Clearance Clinical Impact: The risk of lactic acidosis may increase due to concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2...
Mechanism: Taking these drugs together can increase the risk of a dangerous buildup of lactic acid in the blood, especially if the kidneys are not clearing the medicine properly.
What to do: Your doctor should monitor your kidney function and check for signs of acid buildup in your blood regularly.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What are the common side effects of metformin?
Does metformin interact with other medications?
What drug class is metformin?
Has metformin been recalled?
Active Recalls
CGMP Deviations
Glenmark Pharmaceuticals Inc., USA
Presence of Foreign Tablets/Capsules.
A-S Medication Solutions LLC
CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level.
Nostrum Laboratories Inc
CGMP Deviations: detection of N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Nostrum Laboratories Inc
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Granules Pharmaceuticals Inc
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Amneal Pharmaceuticals of New York, LLC
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Amneal Pharmaceuticals of New York, LLC
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Amneal Pharmaceuticals of New York, LLC
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Amneal Pharmaceuticals of New York, LLC
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Amneal Pharmaceuticals of New York, LLC
CGMP Deviations: FDA analysis detected N-Nitrosodimethylamine (NDMA) impurity above the acceptable intake level
Amneal Pharmaceuticals of New York, LLC
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Other drugs grouped near metformin - same-class peers and common alternatives.
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Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for metformin
The FDA label for metformin (sold under brand names such as Glucophage, Fortamet, Glumetza) classifies it as a prescription-only medication in the Biguanide class. Regulatory labeling describes its approved uses and the patient populations studied in pre-market trials. Official labeling lists 3 commonly reported side effects, including Diarrhea, Upper respiratory tract infection (like a cold), Headache.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 342,023 voluntary reports. The database also lists 27 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $0.64.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 11 recall records on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: June 9, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages