Metformin, sold under the brand name Glucophage among others, is the first-line medication for the treatment of type 2 diabetes, particularly in people who are overweight. It is also used in the treatment of polycystic ovary syndrome. It is not associated with weight gain and is taken by mouth.
Metformin oral tablet comes in two forms: immediate-release and extended-release. The immediate-release tablet is available as the brand-name drug Glucophage. The extended-release tablet is available as the brand-name drugs Glucophage XR, Fortamet, and Glumetza.
How should I use this medicine?
Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. Take this medicine with food. Take your medicine at regular intervals. Do not take your medicine more often than directed. Do not stop taking except on your doctor’s advice.
Immediate-release:
Initial dose: 500 mg orally twice a day or 850 mg orally once a day
-Dose titration: Increase in 500 mg increments weekly or 850 mg every 2 weeks as tolerated
Maintenance dose: 2000 mg/day in divided doses
Maximum dose: 2550 mg/day
Extended-release:
Initial dose: 500 to 1000 mg orally once a day
Dose titration: Increase in 500 mg increments weekly as tolerated
Maximum dose: 2000 mg/day
Switching to Extended-Release:
-Patients receiving immediate-release may switch to extended-release once a day at same total daily dose (up to 2000 mg/day)
Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for children as young as 10 years of age for selected conditions, precautions do apply.
Overdosage: If you think you have taken too much of this medicine, contact a poison control center or emergency room at once.
What if I miss a dose?
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
What is the benefit of taking metformin at night?
Studies have shown that taking extended-release metformin, at night may improve diabetes control by reducing morning hyperglycemia and help to treat high glucose levels overnight. In the early hours of the morning, hormones, including cortisol and growth hormone, signal the liver to boost the production of glucose, which provides energy that helps you wake up.
This triggers beta cells in the pancreas to release insulin in order to keep blood glucose levels in check. But if you have diabetes, you may not make enough insulin or may be too insulin resistant to counter the increase in blood sugar. As a result, your levels may be elevated when you wake up. Taking extended-release metformin, at night can help prevent this by keeping your blood sugar in check.
What may interact with this medicine?
Do not take this medicine with any of the following medications:
- certain contrast medicines given before X-rays, CT scans, MRI, or other procedures
- dofetilide
This medicine may also interact with the following medications:
- acetazolamide
- alcohol
- certain antivirals for HIV or hepatitis
- certain medicines for blood pressure, heart disease, irregular heart beat
- cimetidine
- dichlorphenamide
- digoxin
- diuretics
- female hormones, like estrogens or progestins and birth control pills
- glycopyrrolate
- isoniazid
- lamotrigine
- memantine
- methazolamide
- metoclopramide
- midodrine
- niacin
- phenothiazines like chlorpromazine, mesoridazine, prochlorperazine, thioridazine
- phenytoin
- ranolazine
- steroid medicines like prednisone or cortisone
- stimulant medicines for attention disorders, weight loss, or to stay awake
- thyroid medicines
- topiramate
- trospium
- vandetanib
- zonisamide
This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.
What should I watch out for while using this medicine?
Visit your doctor or health care professional for regular checks on your progress.
A test called the HbA1C (A1C) will be monitored. This is a simple blood test. It measures your blood sugar control over the last 2 to 3 months. You will receive this test every 3 to 6 months.
Always carry a quick-source of sugar with you in case you have symptoms of low blood sugar. Examples include hard sugar candy or glucose tablets. Make sure others know that you can choke if you eat or drink when you develop serious symptoms of low blood sugar, such as seizures or unconsciousness. They must get medical help at once.
Tell your doctor or health care professional if you have high blood sugar. You might need to change the dose of your medicine. If you are sick or exercising more than usual, you might need to change the dose of your medicine.
Do not skip meals. Ask your doctor or health care professional if you should avoid alcohol. Many nonprescription cough and cold products contain sugar or alcohol. These can affect blood sugar.
This medicine may cause ovulation in premenopausal women who do not have regular monthly periods. This may increase your chances of becoming pregnant. You should not take this medicine if you become pregnant or think you may be pregnant. Talk with your doctor or health care professional about your birth control options while taking this medicine. Contact your doctor or health care professional right away if you think you are pregnant.
If you are going to need surgery, a MRI, CT scan, or other procedure, tell your doctor that you are taking this medicine. You may need to stop taking this medicine before the procedure.
Wear a medical ID bracelet or chain, and carry a card that describes your disease and details of your medicine and dosage times.
This medicine may cause a decrease in folic acid and vitamin B12. You should make sure that you get enough vitamins while you are taking this medicine. Discuss the foods you eat and the vitamins you take with your health care professional.
What side effects may I notice from receiving this medicine?
Side effects that you should report to your doctor or health care professional as soon as possible:
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- breathing problems
- feeling faint or lightheaded, falls
- muscle aches or pains
- signs and symptoms of low blood sugar such as feeling anxious, confusion, dizziness, increased hunger, unusually weak or tired, sweating, shakiness, cold, irritable, headache, blurred vision, fast heartbeat, loss of consciousness
- slow or irregular heartbeat
- unusual stomach pain or discomfort
- unusually tired or weak
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
- diarrhea
- headache
- heartburn
- metallic taste in mouth
- nausea
- stomach gas, upset
This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may find useful information on: Does Metformin Expire?
