Weight lossActive ingredient
Metformin hydrochloride
Biguanide1 FDA label read
Metformin is a first-line medication for type 2 diabetes and one of the most widely prescribed medicines in the world. It is often mentioned in discussions of weight, but its FDA label does not list weight loss among the approved uses, and no metformin product has been approved for it.
Highlights of the labels
- Metformin hydrochloride
- Type 2 diabetesnot weight loss
- Supply
- Prescription only
- Generic
- 66 approved applications
- Boxed warning
- WARNING: LACTIC ACIDOSIS
FDA boxed warning
WARNING: LACTIC ACIDOSIS
In the Metformin hydrochloride label
- 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.
A boxed warning is the most serious warning the FDA requires. This text is reproduced from the label.
Brands and what each one is approved for
One active ingredient can hold several separate FDA approvals. They are different documents with different approved uses, and mixing them up is the most common mistake made about these medications.
| Brand | What its label approves | Supply | Label version |
|---|---|---|---|
| Metformin hydrochlorideREMEDYREPACK INC. | What its label approvesType 2 diabetesNot weight loss | SupplyPrescription | Label version19 May 2026 |
How it works
Everything the metformin label says about how the medicine works is about glucose, and the quotation below is the whole of it. Nothing in that description is presented as a route to weight reduction, which matters on this page: metformin comes up in weight discussions constantly, and its own document does not join the two.
Mechanism of action, Metformin hydrochloride label
Metformin is an antihyperglycemic agent which improves glucose tolerance in patients with type 2 diabetes mellitus, lowering both basal and postprandial plasma glucose. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may decrease.
What the FDA approved it for
The approved uses, as worded in the label.
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.
Forms and strengths
The presentations and strengths listed in the label.
Metformin Hydrochloride Tablets USP, 500 mg: White, biconvex, circular shaped film coated tablets with 'A' debossed on one side and '12' debossed on the other side Metformin hydrochloride tablets: 500 mg
How the label says it is taken
What the label states about administration. It is not a dosing instruction for any individual.
- Adult Dosage for Metformin Hydrochloride Tablets: Starting dose: 500 mg orally twice a day or 850 mg once a day, with meals
- Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks, up to a maximum dose of 2550 mg per day, given in divided doses
- Doses above 2000 mg may be better tolerated given 3 times a day with meals
- Increase dosage in increments of 500 mg weekly up to a maximum of 2000 mg per day, given in divided doses twice daily
- Renal Impairment: Prior to initiation, assess renal function with estimated glomerular filtration rate (eGFR)
- Do not use in patients with eGFR below 30 mL/minute/1.73 m 2
Most common adverse reactions
The adverse reactions the label reports as most common.
most common adverse reactions (>5.0%) are diarrhea, nausea/vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache.
Warnings and precautions
The warnings and precautions section of the label.
- Lactic Acidosis: See boxed warning.
- 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.
- 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
Contraindications
Situations in which the label states the medication must not be used.
- Metformin hydrochloride tablets are contraindicated in patients with: Severe renal impairment (eGFR below 30 mL/min/1.73 m 2).
- 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)
Drug interactions
Interactions the label singles out.
- Table 3 presents clinically significant drug interactions with metformin hydrochloride.
- Carbonic anhydrase inhibitors may increase risk of lactic acidosis.
- Consider more frequent monitoring
- Drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) may increase the accumulation of metformin.
- Consider the benefits and risks of concomitant use
- Alcohol can potentiate the effect of metformin on lactate metabolism.
Pregnancy and breastfeeding
The opening of the pregnancy section of the label. The full section is longer and is in the source document.
Limited data with metformin hydrochloride in pregnant women are not sufficient to determine a drug-associated risk for major birth defects or miscarriage. Published studies with metformin use during pregnancy have not reported a clear association with metformin and major birth defect or miscarriage risk. There are risks to the mother and fetus associated with poorly controlled diabetes mellitus in pregnancy.
Generic or brand
Metformin is available as a generic in immediate-release and extended-release forms and is among the least expensive prescription medicines available.
The FDA label database lists 66 approved generic applications for this ingredient.
What affects the cost
Cost is the reason metformin comes up in weight discussions at all: it is inexpensive and long established. That does not change what it is approved for. This site sells nothing and links to no sellers.
What pharmacies pay for it
These are acquisition costs: what pharmacies in the United States pay on average to buy the medication, published weekly by the Centers for Medicare and Medicaid Services. They are not retail prices and not what a person pays at the counter, which depends on insurance, pharmacy and discount programs. They are useful as an objective floor and for seeing how far a brand sits above its generic.
| Measured | Generic |
|---|---|
| per tablet, capsule or pen | Generic$0.025 (range $0.014 to $14.61, 8602 listings) |
| per milliliter | Generic$0.417 (range $0.373 to $0.563, 136 listings) |
Median of 8738 listings. Effective dates 2025-12-17 to 2026-08-26, file dated 2026-08-26.
What the FDA has changed in these labels
The regulator reissues a label without notice: the old wording simply stops existing. These are the latest revisions on record for the documents this page is built from.
- 21 August 2026Metformin hydrochloride
Forms and strengths (1 added)
- 21 May 2026Metformin hydrochloridefrom the archive
Warnings and precautions (4 added)
- 10 February 2025Metformin hydrochloridefrom the archive
Forms and strengths (2 removed)
The full record for every label on this site - 1 earlier revision for this ingredient is in the archive.
Compared with other medications
What the labels do not do is compare one medication against another. These pages put two of them side by side.
Common questions
- Is metformin approved for weight loss?
- No. The FDA label covers glycemic control in type 2 diabetes. Any use for weight is outside the approved indications, and this page does not describe what such use involves.
- Why is metformin in a weight loss category then?
- Because people look for it here. Leaving it out would not answer the question; stating plainly what the label does and does not cover does. Every page in this category marks whether the medication carries an approval for weight management.
Other medications under weight loss
Whether each one carries an FDA approval for this use is marked on its page and in this list.
Sources
Every fact above comes from one of these documents. The date is the effective date of the label version this page was built from.
FDA prescribing information for Metformin hydrochloride
REMEDYREPACK INC.. Label version 14, effective 19 May 2026.
Each stripe is one section of the label, each division in a stripe one entry in that section. The red bar marks a boxed warning.
Page last updated 7 September 2026
Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.