Metformin is an FDA-approved antidiabetic agent that manages high blood sugar levels in type 2 diabetes patients. It reduces glucose absorption from the intestines, lowers liver glucose production, and improves insulin sensitivity. Metformin is recommended with dietary changes and exercise for better results.

Managing blood sugar levels with medications like metformin can prevent complications such as kidney damage, nerve issues, blindness, amputations, and sexual dysfunction. Effective diabetes control can also lower the risk of heart attacks or strokes.

You should not use metformin if you have severe kidney disease, metabolic acidosis, or diabetic ketoacidosis (call your doctor for treatment).

If you need to have any type of x-ray or CT scan using a dye that is injected into your veins, you may need to temporarily stop taking metformin.

Though extremely rare, you may develop lactic acidosis, a dangerous build-up of lactic acid in your blood. Call your doctor or get emergency medical help if you have unusual muscle pain, trouble breathing, stomach pain, dizziness, feeling cold, or feeling very weak or tired.

Metformin comes as a liquid, a tablet, and an extended-release (long-acting) tablet to take by mouth. The liquid is usually taken with meals one or two times a day. The regular tablet is usually taken with meals two or three times a day. The extended-release tablet is usually taken once daily with the evening meal. To help you remember to take metformin, take it around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take metformin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow metformin extended-release tablets whole; do not split, chew, or crush them.

Your doctor may start you on a low dose of metformin and gradually increase your dose not more often than once every 1–2 weeks. You will need to monitor your blood sugar carefully so your doctor will be able to tell how well metformin is working.

Metformin controls diabetes but does not cure it. Continue to take metformin even if you feel well. Do not stop taking metformin without talking to your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Take metformin exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Take metformin with a meal, unless your doctor tells you otherwise. Some forms of metformin are taken only once daily with the evening meal. Follow your doctor's instructions.

Do not crush, chew, or break an extended-release tablet. Swallow it whole.

Measure liquid medicine carefully. Shake the oral suspension before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Some tablets are made with a shell that is not absorbed or melted in the body. Part of this shell may appear in your stool. This is normal and will not make the medicine less effective.

You may have low blood sugar (hypoglycemia) and feel very hungry, dizzy, irritable, confused, anxious, or shaky. To quickly treat hypoglycemia, eat or drink a fast-acting source of sugar (fruit juice, hard candy, crackers, raisins, or non-diet soda).

Your doctor may prescribe a glucagon injection kit in case you have severe hypoglycemia. Be sure your family or close friends know how to give you this injection in an emergency.

Blood sugar levels can be affected by stress, illness, surgery, exercise, alcohol use, or skipping meals. Ask your doctor before changing your dose or medication schedule.

Metformin is only part of a complete treatment program that may also include diet, exercise, weight control, regular blood sugar testing, and special medical care. Follow your doctor's instructions very closely.

Store at room temperature away from moisture, heat, and light.

Your doctor may have you take extra vitamin B12 while you are taking this medicine. Take only the amount of vitamin B12 that your doctor has prescribed.

You should not use metformin if you are allergic to it, or if you have:

• severe kidney disease; or

• metabolic acidosis or diabetic ketoacidosis (call your doctor for treatment).

If you need to have surgery or any type of x-ray or CT scan using a dye that is injected into your veins, you may need to temporarily stop taking metformin. Be sure your caregivers know ahead of time that you are using this medication.

Tell your doctor if you have ever had:

• kidney disease (your kidney function may need to be checked before you take this medicine);

• high ketone levels in your blood or urine;

• heart disease, congestive heart failure;

• liver disease; or

• if you also use insulin, or other oral diabetes medications.

You may develop lactic acidosis, a dangerous build-up of lactic acid in your blood. This may be more likely if you have other medical conditions, a severe infection, chronic alcoholism, or if you are 65 or older. Ask your doctor about your risk.

Follow your doctor's instructions about using metformin if you are pregnant or you become pregnant. Controlling diabetes is very important during pregnancy, and having high blood sugar may cause complications in both the mother and the baby. Tell your doctor if you become pregnant while taking metformin.

Metformin may stimulate ovulation in a premenopausal woman and may increase the risk of unintended pregnancy. Talk to your doctor about your risk.

You should not breastfeed while using this medicine.

Metformin should not be given to a child younger than 10 years old. Some forms of metformin are not approved for use by anyone younger than 18 years old.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose can cause severe hypoglycemia or lactic acidosis.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat, and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Be sure to follow all exercise and dietary recommendations made by your doctor or dietitian. It is important to eat a healthful diet.

Avoid drinking alcohol. It lowers blood sugar and may increase your risk of lactic acidosis.

Get emergency medical help if you have signs of an allergic reaction to metformin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some people using this medicine develop lactic acidosis, which can be fatal. Get emergency medical help if you have even mild symptoms such as:

• unusual muscle pain;

• feeling cold;

• trouble breathing;

• feeling dizzy, light-headed, tired, or very weak;

• stomach pain, vomiting; or

• slow or irregular heart rate.

Common metformin side effects may include:

• low blood sugar;

• nausea, upset stomach; or

• diarrhea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Many drugs can interact with metformin, making it less effective or increasing your risk of lactic acidosis. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

Your doctor will tell you how to check your response to this medication by measuring your blood sugar levels at home. Follow these instructions carefully.

If you are taking the extended-release tablets, you may notice something that looks like a tablet in your stool. This is just the empty tablet shell, and this does not mean that you did not get your complete dose of medication.

You should always wear a diabetic identification bracelet to be sure you get proper treatment in an emergency.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Metformin is quick-acting. You’ll probably see some effects within two days of starting the medicine. The maximum effect can take up to two weeks.

The dosage depends on your medical condition, the formulation you use, your age, and other factors.

Your doctor may start you on a lower dose of metformin and gradually increase it over a few weeks. This will help you avoid unwanted side effects and let your physician monitor your progress.

Typically, patients see the most significant changes in their blood sugar levels when they get to a dose of at least 1,000 milligrams (mg) a day.

Your doctor may recommend a lower dose if you have other medical issues or if you are elderly or malnourished.

Metformin is sometimes used to help conditions it’s not approved to treat. This is called “off-label” use.

Common off-label uses generally target groups of people with underlying insulin resistance.

Some doctors may recommend metformin for:

• Polycystic ovary syndrome (PCOS)
• Weight control
• Gestational diabetes
• Prevention of diabetes in high-risk people

• Actoplus Met® (containing Metformin, Pioglitazone)
• Avandamet® (containing Metformin, Rosiglitazone)
• Invokamet® (containing Canagliflozin, Metformin)
• Janumet® (containing Metformin, Sitagliptin)
• Jentadueto® (containing Linagliptin, Metformin)
• Kazano® (containing Alogliptin, Metformin)
• Kombiglyze® XR (containing Metformin, Saxagliptin)
• Metaglip® (containing Glipizide, Metformin)
• Prandimet® (containing Metformin, Repaglinide)
• Qternmet® XR (containing Dapagliflozin, Metformin, Saxagliptin), Segluromet® (containing Ertugliflozin, Metformin)
• Synjardy® (containing Empagliflozin, Metformin)
• Xigduo® XR (containing Dapagliflozin, Metformin)