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Metformin

Name: Metformin
Brand: Teva
Availability: InStock

Prescription required

$28.00

500 mg · 84 tablets · 3 months supply

Brand· By Merck

$9.33 per month

Brand or generic

Generic packs carry the same active ingredient at the same strength.

Strength

How long a supply?

3 months$9.33 a monthOne-off$28.00

6 months$9.33 a monthOne-off$56.00

Supplied from UK

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Annual cost

$112a year at this pack size

Prescription required

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500 mg

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500-mg

FDA boxed warningLactic 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.

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, and hepatic impairment.

Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided.

If metformin-associated lactic acidosis is suspected, immediately discontinue metformin hydrochloride extended-release tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended.

Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL.
If lactic acidosis is suspected, discontinue metformin hydrochloride extended-release tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended.

Read this with the rest of the clinical information

About Metformin

Overview

Metformin tablets contain metformin hydrochloride, a medicine in the biguanide group. It is used alongside diet and exercise to improve blood sugar control in adults and children aged 10 years and older with type 2 diabetes. It works by helping to lower blood sugar.

What it treats

Type 2 diabetes in adults and children aged 10 years and older, alongside diet and exercise to improve blood sugar control.

Safety information

Side effects

Common side effects include diarrhea, nausea or vomiting, gas, weakness, indigestion, abdominal discomfort and headache. Serious side effects include lactic acidosis. Contact a doctor if this is suspected. Metformin may also cause vitamin B12 deficiency and increase the risk of low blood sugar when used with insulin or medicines that stimulate insulin release. Contact your doctor if you develop these problems.

FDA boxed warning

Lactic acidosis

Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided.

Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL.
If lactic acidosis is suspected, discontinue metformin hydrochloride extended-release tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended.

A boxed warning is the strongest warning the US Food and Drug Administration requires on a medicine label. Text is taken from the official label, with internal section references removed.

When to call your doctor

- Seek medical attention immediately for trouble breathing. - Seek medical attention immediately for unusual sleepiness. - Seek medical attention immediately for muscle pain or feeling generally unwell. - Seek medical attention immediately for abdominal pain. These may be signs of lactic acidosis, a potentially fatal complication of metformin.

If symptoms are severe or getting worse quickly, seek emergency care rather than waiting.

Before taking this medicine

Do not take metformin if you have severe kidney impairment (eGFR below 30 mL/min/1.73 m²), an allergy to metformin, or acute or chronic metabolic acidosis, including diabetic ketoacidosis with or without coma. Use should be avoided in people with liver impairment. Lactic acidosis is a serious warning associated with metformin. Older adults need more frequent kidney function checks. Metformin may lower vitamin B12 levels; blood tests should be checked annually and vitamin B12 levels every 2 to 3 years. Taking metformin with insulin or medicines that stimulate insulin release increases the risk of low blood sugar. Premenopausal women should be aware of the potential for an unintended pregnancy.

Interactions

Topiramate, zonisamide, acetazolamide and dichlorphenamide may increase the risk of lactic acidosis, a buildup of lactic acid in the blood, when taken with metformin. More frequent monitoring may be needed. Ranolazine, vandetanib, dolutegravir and cimetidine can reduce the removal of metformin by the kidneys, increasing metformin levels and potentially the risk of lactic acidosis. Your doctor should review the benefits and risks of using these medicines together. Avoid excessive alcohol intake while taking metformin. Alcohol can increase metformin’s effect on how the body processes lactic acid. Insulin and medicines that stimulate insulin release, such as sulfonylureas, may increase the risk of low blood sugar when used with metformin. Your prescriber may need to adjust these medicines. Some medicines can raise blood sugar and make it harder to control. These include thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blockers and isoniazid. Tell your doctor if you start or stop any of these: closer monitoring may be needed for high blood sugar when starting them and low blood sugar when stopping them.

Using Metformin

Dosing

Dosing is set by your prescriber. Each health care professional may prescribe medication differently according to a patient's medical history and condition, so follow the directions on your prescription label and speak to your doctor or pharmacist before changing anything.

Storage

Store below 25°C in a dry place, in the original pack, away from direct light and moisture. Do not keep it in a bathroom. Keep all medicines out of the sight and reach of children.

Clinical information on this page is summarised from the US FDA label METFORMIN (METFORMIN ER 500 MG) TABLET, EXTENDED RELEASE [REMEDYREPACK INC.] (DailyMed, retrieved 19 September 2026).

Patient information and references

Official and supporting information to read alongside advice from your prescriber or pharmacist.

Patient information leaflet (PDF)

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