Generic Name: metformin (met-FOR-min)
Brand Name: Glucophage
Metformin may rarely cause a serious and sometimes fatal condition called lactic acidosis. Most of these cases have occurred in diabetic patients who also have certain kidney problems. The risk of lactic acidosis may be greater if you have liver problems, kidney problems, or heart failure. The risk may also be greater in patients who are elderly or drink alcohol. Lab tests, including kidney function, may be performed while you take metformin.
Do not begin to take metformin if you are 80 years or older unless lab tests show that you do not have decreased kidney function. Do not take it if you have a severe infection, have low blood oxygen levels, or are dehydrated. Tell your doctor you take metformin before you have any surgery or lab procedures.
Contact your doctor right away if you notice symptoms such as muscle pain or tenderness; unusual drowsiness, dizziness, or light-headedness; slow or irregular heartbeat; fast or difficult breathing; unusual stomach discomfort; or unusual weakness or tiredness. Contact your doctor right away if you start to feel unusually cold or if you have a general feeling of being unwell.
Metformin is used for:
Treating type 2 diabetes. It is used along with diet and exercise. It may be used alone or with other antidiabetic medicines.
Metformin is a biguanide antidiabetic. It works by decreasing the amount of sugar that the liver produces and the intestines absorb. It also helps to make your body more sensitive to the insulin that you naturally produce.
Do NOT use metformin if:
- you are allergic to any ingredient in metformin
- you have a severe infection, low blood oxygen levels, kidney or liver problems, high blood ketone or acid levels (eg, diabetic ketoacidosis), or dehydration
- you have had a stroke or a recent heart attack, or you are in shock
- you are 80 years or older and have not had a kidney function test
- you will be having surgery or certain lab procedures
Contact your doctor or health care provider right away if any of these apply to you.
Before using metformin:
Some medical conditions may interact with metformin. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have heart failure, especially heart failure that is treated by medicine
- if you have a history of heart problems, lung or breathing problems, thyroid problems, stomach or bowel problems (eg, paralysis, blockage), adrenal or pituitary problems, or lactic acidosis
- if you have vomiting, diarrhea, poor health or nutrition, low blood calcium or vitamin B12 levels, or anemia, or if you are dehydrated
- if you have an infection, fever, recent injury, or moderate to severe burns
- if you drink alcohol or have a history of alcohol abuse
- if you will be having surgery or certain lab procedures
- if you take a beta-blocker (eg, propranolol)
Some MEDICINES MAY INTERACT with metformin. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Amiloride, cimetidine, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, vancomycin, or medicines that may harm the kidney (eg, aminoglycoside antibiotics [eg, gentamicin], amphotericin B, tacrolimus) because they may increase the risk of metformin's side effects. Ask you doctor if you are unsure if any of your medicines might harm the kidney
- Calcium channel blockers (eg, nifedipine), corticosteroids (eg, prednisone), diuretics (eg, furosemide, hydrochlorothiazide), estrogen, hormonal contraceptives (eg, birth control pills), insulin, isoniazid, nicotinic acid, phenothiazine (eg, chlorpromazine), phenytoin, sulfonylureas (eg, glipizide), sympathomimetics (eg, albuterol, pseudoephedrine), or thyroid hormones (eg, levothyroxine) because the risk of high or low blood sugar may be increased
This may not be a complete list of all interactions that may occur. Ask your health care provider if metformin may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
How to use metformin:
Use metformin as directed by your doctor. Check the label on the medicine for exact dosing instructions.
- An extra patient leaflet is available with metformin. Talk to your pharmacist if you have questions about this information.
- Take metformin by mouth with food.
- Take metformin on a regular schedule to get the most benefit from it. Taking metformin at the same time each day will help you remember to take it.
- Continue to take metformin even if you feel well. Do not miss any doses.
- If you miss a dose of metformin, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use metformin.
Important safety information:
- Metformin may cause dizziness. This effect may be worse if you take it with alcohol or certain medicines. Use metformin with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it
- Follow the diet and exercise program given to you by your health care provider.
- Do not drink large amounts of alcohol while you take metformin. Talk to your doctor or health care provider before you drink alcohol while you take metformin.
- Tell your doctor or dentist that you take metformin before you receive any medical or dental care, emergency care, or surgery.
- Be careful not to become dehydrated, especially during hot weather or while you are being active. Dehydration may increase the risk of metformin's side effects.
- If vomiting or diarrhea occurs, you will need to take care not to become dehydrated. Contact your doctor for instructions.
- Carry an ID card at all times that says you have diabetes. Check your blood sugar levels as directed by your doctor. If they are often higher or lower than they should be and you take metformin exactly as prescribed, tell your doctor.
- Metformin does not usually cause low blood sugar. Low blood sugar may be more likely to occur if you skip a meal, exercise heavily, or drink alcohol. It may also be more likely if you take metformin along with certain medicines for diabetes (eg, sulfonylureas, insulin). Tell your doctor right away if you experience symptoms of low blood sugar (eg, fast heartbeat, headache, chills, sweating, tremors, increased hunger, vision changes, nervousness, weakness, dizziness, drowsiness, fainting).
- It is a good idea to carry a reliable source of glucose (eg, tablets or gel) to treat low blood sugar. If this is not available, you should eat or drink a quick source of sugar like table sugar, honey, candy, orange juice, or non-diet soda. This will raise your blood sugar level quickly. Tell your doctor right away if this happens. To prevent low blood sugar, eat meals at the same time each day and do not skip meals.
- Fever, infection, injury, or surgery may increase your risk of high or low blood sugar levels. If any of these occur, check your blood sugar level closely and tell your doctor right away.
- Metformin may commonly cause stomach upset, indigestion, nausea, vomiting, or diarrhea at the beginning of treatment. If you develop unusual or unexpected stomach problems, or if you develop stomach problems later during treatment, contact your doctor at once. This may be a sign of lactic acidosis.
- Lab tests, including kidney function, fasting blood glucose, hemoglobin A1c, and complete blood cell counts, may be performed while you take metformin. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
- Use metformin with caution in the ELDERLY; they may be more sensitive to its effects. Low blood sugar levels may also be more difficult to recognize in the elderly.
- Metformin should not be used in CHILDREN younger than 10 years; safety and effectiveness in these children have not been confirmed.
- PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of taking metformin while you are pregnant. It is not known if metformin is found in breast milk. Do not breast-feed while taking metformin.
When used for long periods of time, metformin may not work as well. If your blood sugar has been under control and then becomes hard to manage, contact your doctor. Do not change the dose of your medicine without checking with your doctor.
Possible side effects of metformin:
All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur:
Diarrhea; gas; headache; indigestion; nausea; stomach upset; temporary metallic taste; vomiting.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); chest pain or discomfort; dizziness or light-headedness; fast or difficult breathing; feeling of being unusually cold; fever, chills, or persistent sore throat; general feeling of being unwell; muscle pain or weakness; slow or irregular heartbeat; unusual drowsiness; unusual or persistent stomach pain or discomfort; unusual tiredness or weakness.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.
If OVERDOSE is suspected:
Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include dizziness or light-headedness; fast or difficult breathing; feeling of being unusually cold; general feeling of being unwell; muscle pain or tenderness; slow or irregular heartbeat; unusual drowsiness; unusual stomach discomfort; unusual weakness or tiredness.Proper storage of metformin:
Store metformin at room temperature, between 68 and 77 degrees F (20 and 25 degrees C). Brief storage at temperatures between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Store away from heat, moisture, and light. Do not store in the bathroom. Keep metformin out of the reach of children and away from pets.
- If you have any questions about metformin, please talk with your doctor, pharmacist, or other health care provider.
- Metformin is to be used only by the patient for whom it is prescribed. Do not share it with other people.
- If your symptoms do not improve or if they become worse, check with your doctor.
- Check with your pharmacist about how to dispose of unused medicine.
This information should not be used to decide whether or not to take metformin or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about metformin. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to metformin. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using metformin.
Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.