What is metformin?

Metformin is an oral diabetes medicine that helps control blood sugar levels.

Metformin is for people with type 2 (non-insulin-dependent) diabetes. Metformin is sometimes used in combination with insulin or other medications, but it is not for treating type 1 diabetes.

Metformin may also be used for other purposes not listed in this medication guide.

Precautions

Some people have developed a life-threatening condition called lactic acidosis while taking metformin. Get emergency medical help if you have any of these symptoms of lactic acidosis: weakness, increasing sleepiness, slow heart rate, cold feeling, muscle pain, shortness of breath, stomach pain, feeling light-headed, and fainting.

You may be more likely to develop lactic acidosis if you have congestive heart failure. Older adults may also have a higher risk of developing lactic acidosis. Talk with your doctor about your individual risk.

Do not use this medication if you are allergic to metformin, if you have kidney disease or kidney failure, or if you are in a state of diabetic ketoacidosis (call your doctor for treatment with insulin).

Before taking this medication, tell your doctor if you are allergic to any drugs, or if you have:

  • liver disease; or
  • a history of heart disease.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take metformin.

FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether metformin passes into breast milk or if it could harm a nursing baby. Do not take metformin without first talking to your doctor if you are breast-feeding a baby.

Metformin should not be given to a child younger than 10 years old. Extended-release metformin (Glucophage XR) should not be given to a child younger than 17 years old.

Avoid drinking alcohol while taking metformin. Alcohol lowers blood sugar and may increase the risk of lactic acidosis while you are taking this medicine.

Back to top

Instructions

Seek emergency medical attention if you think you have used too much of this medicine. You may have signs of low blood sugar, such as hunger, headache, confusion, irritability, drowsiness, weakness, dizziness, tremors, sweating, fast heartbeat, seizure (convulsions), fainting, or coma.

An overdose of metformin may cause a life-threatening condition called lactic acidosis. Get emergency medical help if you have any of these symptoms of lactic acidosis: weakness, increasing sleepiness, slow heart rate, cold feeling, muscle pain, shortness of breath, stomach pain, feeling light-headed, and fainting.

Take the missed dose as soon as you remember (be sure to take the medicine with food). If it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. Do not take extra medicine to make up the missed dose.

Back to top

Side Effects

Get emergency medical help if you have any of these symptoms of lactic acidosis: weakness, increasing sleepiness, slow heart rate, cold feeling, muscle pain, shortness of breath, stomach pain, feeling light-headed, and fainting.

Stop using metformin and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • feeling short of breath, even with mild exertion;
  • swelling or rapid weight gain; or
  • fever, chills, body aches, flu symptoms.

Less serious side effects may include:

  • headache or muscle pain;
  • weakness; or
  • mild nausesa, vomiting, diarrhea, gas, stomach pain.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

Back to top

Interactions

You may be more likely to have hyperglycemia (high blood sugar) if you are taking metformin with other drugs that raise blood sugar. Drugs that can raise blood sugar include:

  • isoniazid;
  • diuretics (water pills);
  • steroids (prednisone and others);
  • phenothiazines (Compazine and others);
  • thyroid medicine (Synthroid and others);
  • birth control pills and other hormones;
  • seizure medicines (Dilantin and others); and
  • diet pills, or medicines to treat asthma, colds or allergies.

You may be more likely to have hypoglycemia (low blood sugar) if you are taking metformin with other drugs that lower blood sugar. Drugs that can lower blood sugar include:

  • some nonsteroidal anti-inflammatory drugs (NSAIDs);
  • aspirin or other salicylates (including Pepto-Bismol);
  • sulfa drugs (Bactrim and others);
  • a monoamine oxidase inhibitor (MAOI);
  • beta-blockers (Tenormin and others); or
  • probenecid (Benemid).

Some medications may interact with metformin. Tell your doctor if you are using any of the following drugs:

  • furosemide (Lasix);
  • nifedipine (Adalat, Procardia);
  • cimetidine (Tagamet) or ranitidine (Zantac);
  • amiloride (Midamor) or triamterene (Dyrenium);
  • digoxin (Lanoxin);
  • morphine (MS Contin, Kadian, Oramorph);
  • procainamide (Procan, Pronestyl, Procanbid);
  • quinidine (Cardioquin, Quinidex, Quinaglute);
  • trimethoprim (Proloprim, Primsol, Bactrim, Cotrim, Septra); or
  • vancomycin (Vancocin, Lyphocin).

This list is not complete and there may be other drugs that can interact with metformin. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Other Names

Fortamet, Glucophage, Glucophage XR, Glumetza, Riomet, and metformin

Back to top

Disclaimer

Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2004 Cerner Multum, Inc. Version 2.05. Revision date 8/23/04

Last updated: