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Metformin

Why it's used

Metformin is used to reduce the high blood sugar level due to improper production or use of insulin in the body (also called, type 2 diabetes mellitus). It is a prescription medicine. It works by lowering the amount of glucose in the body. It also increases the response of the body to insulin.
Metformin may also be taken in combination with other medicines to treat certain conditions as recommended by the doctor. Metformin is used together with sulphonylureas to lower the total cholesterol levels in the blood and may increase the risk of low blood sugar levels (hypoglycemia).
When not to use
Metformin cannot be used to treat high blood sugar level due to the absence of insulin production (type 1 diabetes mellitus).
Anti-Diabetic
Metformin belongs to a class of medicines called Anti-Diabetic. Anti-diabetic drugs are a class of medicines used to treat diabetes mellitus. It control diabetes by lowering the sugar level in the blood. Antidiabetic drugs include insulin and the oral hypoglycemic agents.

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How to use

Follow directions on the product label, information guide, and provided by your doctor before using Metformin. Consume this medicine as per your doctor's instructions.
Metformin is consumed with food. This medicine should be taken with meals two or three times a day. Metformin is consumed usually in the evening.

Typical Dosage

The typical adult dose of Metformin is initial dose of 850 mg once a day or 500 mg twice a day with food (not more than 2550 mg in a day). The typical dose for children is initial dose of 500 mg twice a day (not more than 2000 mg in children 10-16 years). The maximum dose for adults of Metformin is 2550 mg per day. There are no known habit-forming tendencies with this medicine.
Metformin is to be used for longer periods of time. You should continue to use this medicine as directed by the doctor even if you feel well.
To decrease the possibility of side-effects, you might be recommended to use the extended-release form of this medicine by your doctor. The extended-release medicine helps in maintaining a steady level of the medicine in your body for a longer period of time. Do not crush or chew the medicine, unless indicated on the package or by your doctor.

Talk to Your Doctor

Tell your doctor if you develop new symptoms. If you have any kidney disease, dosage will usually be adjusted according to the functioning of kidney parameter (glomerular filtration rate).
To see the impact of Metformin on the body, your doctor may recommend a lower initial dose. Please follow your doctor's instructions carefully. A lower dose of Metformin may be recommended to reduce the risk of side-effects. Older patients may see an increase in the risk of side-effects. Hence, a lower dose may be recommended.
When stopping this medicine, it is possible that you may experience withdrawal symptoms such as low sugar level.

Use in Children

If you are giving Metformin to a child, be sure to use a product that is meant for use in children. Before giving this medicine, use the child's weight or age to find the right dose from the leaflet or product package. You can also read the dosage section of this page to know the correct dose for your child. Else, consult with your doctor and follow their recommendation.

Limit Alcohol

Limit drinking alcohol with Metformin.

Lab Tests

Your doctor may require that certain tests be performed before using Metformin. The doctor may ask you to have Estimated Glomerular Filtration Rate test. A glomerular filtration rate should be tested before this medicine because the dosage of Metformin depends on this test.

Storage

Store Metformin at room temperature 20°–25° C (68°–77° F), away from moisture, and away from light. Keep this medicine away from children and pets.
Medicines may be given for uses other than those listed in the medicine guide. Do not use Metformin for symptoms for which it was not prescribed. Do not give Metformin to others who may have similar symptoms as you. Self-medication can cause harm.

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How to take Metformin

Your dose and how often you take Metformin will depend on the following factors:
  • age
  • patient's health
  • the health of the patient's liver
  • the health of the patient's kidneys
  • medicines recommended by the doctor
  • any other medicines being used
  • herbal supplements in use

Metformin Dosage

Dosage for type 2 diabetes mellitus

Adult
  • Initial: 500 mg twice a day or 850 mg once a day with food
  • Maximum: 2550 mg/day once daily in evening with food
Children (10-16 years)
  • Initial: 500 mg twice a day with food
  • Maximum: 2000 mg/day

Minimum Age

10 years

Dosage calculation for children

To calculate the dosage for children please use the weight based dose calculator to calculate the appropriate dosage as per the weight of your child.

Forms

Tablets
Strength: 500 mg, 850 mg, and 1000 mg
Extended-Release Tablets
Strength: 500 mg and 750 mg
Sustained-Release Tablets
Strength: 500 mg, 750 mg, and 1000 mg
Oral solution
Strength: 500 mg/5 ml

Special Instructions

Extended-release tablet
Swallow this medicine whole, without splitting, chewing or crushing them. This medicine is usually taken once daily with the evening food.
Oral solution

Missed Dose

A missed dose should be taken with food as soon as you remember it. Avoid taking a double dose to make up for a missed dose.

Overdose

What to do if you overdose on Metformin?
The most useful and effective method to remove excessive amounts of lactate and Metformin is hemodialysis. Hemodialysis is a process used to purify the blood by removing harmful substances from the body.
Symptoms of an overdose of Metformin
If you use too much of this medicine, it could lead to dangerous levels of the medicine in your body. In such cases, symptoms of an overdose may include:
  • abnormal heart rate
  • buildup of lactate in the body
  • difficulty in breathing
  • drowsiness
  • fatal
  • feeling of discomfort
  • low blood pressure
  • muscle pain
  • reduced body temperature
  • severe tiredness
  • stomach pain
  • vomiting
If you think you have overdosed on Metformin, call a poison control center immediately. You can look up the poison control center information from the Poison Center Finder at TabletWise.com.

Precautions while using Metformin

Before you use Metformin, tell your doctor of your medical and health history including the following:
  • abnormal functioning of the kidney
  • abnormal functioning of the liver
  • alcoholism
  • dehydration
  • heart failure
  • high acid level in the body (long-term metabolic acidosis)
  • high ketone acids in the blood (diabetic ketoacidosis)
  • patients taking iodinated contrast agents through arteries
  • prior exposure to surgery
  • severe infection heart attack
  • stroke
Taking Metformin in patients with alcoholism, abnormal functioning of kidney and liver may lead to the buildup of lactate in the body. Also, the use of Metformin before or at the time of surgery may increase the risk for fluid loss, low blood pressure, and abnormal functioning of the kidney.
Before you use Metformin, tell your doctor if you are allergic to it or its ingredients. Your doctor may prescribe an alternative medicine and update your medical records to record this information.
Before having any surgery, discuss with your doctor and dentist about medicines you use including prescription medicines, non-prescription medicines, and herbal supplements.
The use of Metformin may change hematologic parameters (hemoglobin/hematocrit and red blood cell). Patients using this medicine may experience red blood cell deficiency.

Use when Pregnant

Metformin is not safe for use in women who are pregnant. If you are pregnant or planning to become pregnant, you should discuss the impact on the fetus with your doctor before you start using this medicine.

If Breastfeeding

Metformin is not safe for use in women who are breastfeeding. If you are breastfeeding, discuss with your doctor if you should either discontinue breastfeeding, or stop using this medicine during this period. This medicine may pass into breast milk.

If trying to Conceive

Consult with your doctor on the use of Metformin, if you are trying to conceive.

Alcohol

Limit drinking alcohol with Metformin. Consumption of alcohol may cause buildup of lactate in the body.

Side-effects in Older Patients

Older patients may have a higher incidence of side-effects when using Metformin. Elderly patients may see an increased risk of build up of lactate in the body.

What precautions should be taken during Pregnancy and Nursing, and administering Metformin to Children or the Older Adults?

Pregnant Women

Contraindicated or Not Recommended
Warning: There is no clinical data available in pregnant women.

Breastfeeding

Only When Necessary
Warning: Use this medicine only if the potential benefit outweighs the risk to infant during breastfeeding.

Younger Adults Population

No Known Risk
Warning: This medicine should not be used in children below 10 years due to lack of safety data.

Older Adults Population

Precaution
Warning: Usually, a low dose of Metformin should be started in elderly patients to avoid the risk of the build-up of lactate in the body.

Metformin Side-effects

The following side-effects may commonly occur when using Metformin. If any of these side-effects worsen or last for a long time, you should consult with your doctor:
The following side-effects may commonly occur in older patients on the use of Metformin. Discuss with your doctor if any of these side-effects last for a long time or are severe:
  • build up of lactate in the body (lactic acidois)
Rarely, the use of Metformin may cause the following side-effects:
The following severe side-effects may also occur when using Metformin:
Your doctor has prescribed Metformin because they judge that the benefit is greater than the risk posed by side-effects. Many people using this medicine do not have serious side-effects. This page does not list all possible side-effects of Metformin.
If you experience side-effects or notice other side-effects not listed above, contact your doctor for medical advice. You may also report side-effects to your local food and drug administration authority. You can look up the drug authority contact information from the Drug Authority Finder at TabletWise.com.

Side-effects and Allergic Reactions of Metformin by Severity and Frequency

Common Side-effects

Following are the common side-effects of this medicine:

Infrequent and Rare Side-effects

Following are the infrequent and rare side-effects of this medicine:

Severe Side-effects

Following are the severe side-effects of this medicine:

Side-effects in Older Adults

Following are the side-effects of this medicine in elderly patients:

Mild Allergic Reactions

Following are the symptoms of mild allergic reactions to this medicine:
If any of these symptoms occur, do not take this medicine.

Serious Allergic Reactions

Following are the symptoms of serious allergic reactions to this medicine:
If you have any symptoms of serious side-effects, avoid the use of this medicine.
If you experience side-effects or notice other side-effects not listed above, contact your doctor for medical advice. You may also report side-effects to your local food and drug administration authority. You can look up the drug authority contact information from the Drug Authority Finder at TabletWise.com.

Warnings

Elderly Patients

Metformin may increase the risk of lactate buildup in the body in elderly patients. Proper monitoring of the functioning of the kidneys is recommended in elderly patients. Avoid the use of Metformin in these patients.

Alcohol Consumption

Excessive alcohol consumption may lead to an increased risk of the build-up of lactate in the body (lactic acidosis). Avoid the consumption of alcohol while taking Metformin.

Heart Failure

Patients with heart failure are at an increased risk when using this medicine. Such patients may see an increased risk of the low level of oxygen in the blood (hypoxemia) and abnormal functioning of the kidney. In patients with stable long-term heart failure, appropriate monitoring of the functioning of the heart and kidney is required while using this medicine. The use of Metformin is not recommended in patients with unstable heart failure.

Surgery

Patients at the time of surgery under anesthesia are at an increased risk when using Metformin. Discontinue the use of Metformin at the time of surgery for at least 48 hours. Restart the use of this medicine after the resumption of oral nutrition or if the functioning of the kidney becomes stable.

Iodinated Contrast Agents

Use of iodinated contrast agents which are taken through the blood vessels (intravascular) may increase the risk of the build-up of lactate inside the body, decrease the functioning of the kidney. Discontinue the use of Metformin before or at the time of treatment with iodinated contrast agents for at least 48 hours. Restart the use of this medicine if the functioning of the kidney becomes stable.

Severe Conditions of Vomiting, Diarrhea, or Fever

Patients with severe conditions of vomiting, diarrhea, or fever may experience severe loss of water in the body (severe dehydration). Discontinue the use of Metformin for a shorter time duration and consultation with a doctor is advised.

Build Up of Lactate in the Body

Patients with diabetes, prolonged fasting, alcohol intake, serious infections, liver problems, dehydration, and decreased supply of oxygen are at increased risk when using this medicine. Patients using Metformin are at an increased risk of low body temperature, low blood pressure, abnormal heartbeat, and fatal conditions. These patients may see an increased level of lactate, Metformin, lactate/pyruvate ratio, and abnormal levels of negatively charged ions in the blood. Such patients may also develop symptoms of lactic acidosis such as a feeling of discomfort, muscle pain, etc. Discontinue the use of Metformin in these conditions. Supportive measures and immediate use of a therapy that purifies the blood (hemodialysis) is also recommended.

Interactions with Metformin

When two or more medicines are taken together, it can change how the medicines work and increase the risk of side-effects. In medical terms, this is called as a Drug Interaction.
This page does not contain all the possible interactions of Metformin. Share a list of all medicines that you use with your doctor and pharmacist. Do not start, stop, or change the dose of any medicines without the approval of your doctor.

Multidrug and Toxin Extrusion Inhibitors

Metformin interacts with multidrug and toxin extrusion inhibitors (such as ranolazine, vandetanib, dolutegravir, isavuconazole, trimethoprim, and cimetidine), which are used to treat chest pain, ulcer, cancer, bacterial, viral, and fungal infections. Use of Metformin with multidrug and toxin extrusion inhibitors (MATE), increases the level of Metformin in the body. It may also increase the risk of lactate buildup in the body. Dose adjustment is needed while using these medicines in combination.

Calcium Channel Blockers

There may be an interaction of Metformin with Calcium Channel Blockers such as nifedipine, which is used to treat high blood pressure, and chest pain. When Metformin is used with nifedipine, the level of Metformin gets increased in the blood.

Diuretics

Metformin may interact with Diuretics such as furosemide, which is used to treat fluid build-up in patients with heart failure or kidney disease and conditions of high blood pressure. Use of furosemide with Metformin increases the level of Metformin in the blood. Proper monitoring of the functioning of the kidney and blood glucose levels test is required to adjust the dose of Metformin.

Other Drugs

Your doctor's guidelines may need to be followed while taking this medicine along with Other drugs including thyroid products, oral contraceptives, estrogens, corticosteroids, phenothiazines, phenytoin and nicotinic acid which are used to treat hormone imbalance, central nervous system disorders, seizures and vitamin B deficiency. When Metformin is used with these medicines, may lead to loss of blood glucose control. Proper monitoring of low blood sugar levels is required in such patients.

Antihypertensive Agents

Special instructions need to be followed while taking this medicine along with thiazides, diuretics, sympathomimetics, and calcium channel blockers, which are used to treat blood pressure. When Metformin is used with thiazides, diuretics, sympathomimetics or calcium channel blockers, may lead to loss of blood glucose control. These patients should be observed closely for low blood sugar levels.

Organic Cationic Transporter Inducers-1

Your doctor's guidelines may need to be followed while taking this medicine along with inducers of organic cationic transporter-1 (rifampicin), which are used to treat bacterial infections. When Metformin is used with organic cation transporter-1 inducer, may increases the absorption in stomach and intestine and alters the effectiveness of Metformin. Appropriate adjustment of dosage is required while taking both drugs.

Organic Cationic Transporter Inhibitors-1 and 2

Special instructions need to be followed while taking this medicine along with inhibitors of organic cationic transporter-1 and organic cationic transporter- 2 (crizotinib, olaparib), which are used to treat cancer. When Metformin is used with crizotinib, olaparib may alter the effectiveness and removal of Metformin from the kidney. Appropriate adjustment of dosage is required while taking both drugs.

Non-Steroidal Anti-Inflammatory Drugs

Metformin interacts with Nonsteroidal Anti-Inflammatory Drugs including selective cyclooxygenase-2 inhibitors, angiotensin II receptor blockers, and angiotensin-converting enzyme inhibitors which are used to treat pain, fever, inflammation and high blood pressure. Use of Metformin with these drugs may affect the functioning of the kidney which further leads to the risk of lactate build-up in the body. Close monitoring of the functioning of the kidney is required when using these drugs with Metformin.

Iodinated Contrast Agents

There may be an interaction of Metformin with Iodinated Contrast Agents, which are used during X-ray procedure. Use of iodinated contrast agents which are given through the blood vessels may increase the risk of acid build up inside the body and decrease the functioning of the kidney. Do not take this medicine in patients with abnormal functioning of the liver or kidney, alcoholism or heart failure and in the patients who are taking iodinated contrast through arteries. Discontinue the use of Metformin before or at the time of treatment with iodinated contrast agents.

Carbonic Anhydrase Inhibitors

Metformin may interact with Carbonic Anhydrase Inhibitors (such as topiramate, zonisamide, acetazolamide, dichlorphenamide), which are used to treat damaged optic nerve (glaucoma). Use of Metformin with carbonic anhydrase inhibitors may increase the risk of lactate build-up in the body. Frequent monitoring is required in these patients.

Interactions of Metformin by Severity

Severe

The following medicines are usually not to be taken together without consulting with your doctor or pharmacist.

When should Metformin be not used?

Abnormal Functioning of the Kidney

This medicine should not be used in patients with abnormal functioning of the kidney. These patients are at increased risk of the build-up of Metformin and lactate in the body. These patients may have the following symptoms if they use this medicine:

Allergic to Metformin

This medicine should not be used in patients allergic to Metformin. These patients may have the following symptoms if they use this medicine:

Coma Due to High Blood Sugar

This medicine should not be used in patients with diabetic pre-coma.

Dehyration, Infection, Shock, and Heart Disease

This medicine should not be used in patients with dehydration, severe infection, shock and heart disease. These patients are at increased risk of lactate build-up in the body. These patients may have the following symptoms if they use this medicine:

Liver Failure, Alcoholism, and Respiratory Failure

This medicine should not be used in patients with liver failure, respiratory failure, alcohol poisoning, and alcoholism. These patients are at increased risk of lactate build-up in the body. These patients may have the following symptoms if they use this medicine:

Increased Production of Acid in the Body

This medicine should not be used in patients with metabolic acidosis.

Brands

Following are the top brand names of Metformin in countries around the world:

Traveling With Medication

  • Ensure that you carry enough doses of each of your prescription medicines to last the entire trip. The best place to store your medicines is in the carry on baggage. However, while flying, if carrying liquid medicines, make sure you do not go over the limits imposed for carry-on liquids.
  • While traveling overseas, make sure that you can carry each of your prescription medicines legally to your destination country. One way to ensure this is by checking with your destination country's embassy or website.
  • Make sure that you carry each of your medicines in their original packaging, which should typically include your name and address, and the details of the prescribing doctor.
  • If your travel involves crossing time zones, and you are required to take your medicine as per a fixed schedule, make sure that you adjust for the change in time.

Expired Medication

Taking a single dose of expired Metformin is unlikely to cause a side-effect. However, please discuss with your doctor or pharmacist, if you feel unwell or sick. An expired medicine may become ineffective in treating your prescribed conditions. To be on the safe side, it is important not to use an expired drug. You are much safer by always keeping a fresh supply of unexpired medicines.

Safe Disposal of Medication

  • If there are disposal instructions on the package, please follow the instructions.
  • If there are medicine take-back programs in your country, you should contact the respective authority to arrange for the disposal of the medicine. For example, in the USA, the Drug Enforcement Administration regularly hosts National Prescription Drug Take-Back events.
  • If there are no take-back programs, mix the medicine with dirt and place them in a sealed plastic bag. Throw the plastic bag in your household trash. Separately, remove all personal information including the prescription label from the medicine packaging and then dispose off the container.
  • If specifically indicated on the medicine package that it needs to be flushed down the toilet when no longer needed, perform the required step.
This page provides information for Metformin .

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