Metformin Oral: Uses, Side Effects, Dosage & Interactions

Medically Reviewed By DR. PRIYANKA CHAKRAVARTY INDU, PhD November 8, 2023

Last updated on July 19th, 2023

Type 2 diabetes global prevalence rates are increasing and this is a great concern. When the body becomes insulin resistant, the blood glucose levels increases leading to type 2 diabetes. Efficient management of type 2 diabetes is necessary so that its serious consequences like heart disease, renal failure, foot and nerve damage, etc. can be avoided.

For efficient type 2 diabetes treatment there is a need to have a balanced and integrated approach. The integrated approach involves regular monitoring of blood glucose levels, proper diet plan, changes in lifestyle, and medication.

Metformin is a popular medicine used for treating type 2 diabetes.

Action of Metformin

The treatment of type-2 diabetes mainly aims to control blood glucose levels. The blood glucose levels are high due to insulin resistance and a decrease in insulin production. Type 2 diabetes is more common in people who are obese and who are less physically active.

The liver is an important organ in maintaining proper glucose levels in the body. When the nutrients enter the bloodstream, the pancreases secrete the insulin. It is this insulin that helps glucose absorption. The liver stores this excessive glucose. This is hepatic glycogen.

When the body needs energy in emergency conditions liver breaks down the hepatic glycogen to release glucose [1]. But in diabetes, the body becomes resistant to insulin. It gradually leads to the damage of beta cells which results in insulin deficiency. In such a case liver gets a signal that the body requires energy.

The energy signal to the liver causes it to start using its stored hepatic glucose. This glucose now enters the bloodstream. This causes an increase in blood glucose levels. In type 2 diabetes hepatic glucose production is high [2].

Actions of metformin

Metformin action decreases this hepatic glucose production by the liver. The medicine inhibits the respiratory chain of the liver. AMPK is activated due to this inhibition [1]. The activation of AMPK results in a lowering of hepatic glucose production and an increase in insulin sensitivity. Glucose utilization increases in the intestine. The medicine also regulates hepatic glucose output [1].

Balanced with proper diet, lifestyle change, and weight management methods, the Metformin drug should be used. Many patients with type 2 diabetes may need to take insulin by injection.


Metformin acts by stopping the respiratory chain in the liver. This decreases hepatic glucose breakdown by the liver and increases insulin sensitivity.

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Metformin tablet uses

Metformin tablet has diversified uses. The most common usage is to manage type 2 diabetes.

  1. Type 2 Diabetes treatment: It treats type 2 diabetes well and keeps it in control with proper food, exercise. It controls type 2 diabetes by decreasing hepatic glucose production, increasing insulin sensitivity, and increasing glucose utilization [1].
    Benefits: When controlling blood sugar level, renal damage, neuro problems, blindness, sexual dysfunctions can be prevented. You can even escape from cardiac arrest and stroke with controlled blood sugar. Therefore have effective diabetes management.
  2. Weight management: Metformin Hydrochloride Tablets ip 500mg uses for weight management. Research says that the drug helps some of us in weight loss also called Metformin weight loss. But, it is unclear why it does so? A theory states that metformin makes you eat less by reducing your appetite. It also alters the usage of stored fat. However, your weight loss journey does not occur overnight. The process gradually takes a few years. The amount of weight loss varies for every person. 4-7 pounds’ weight loss expected after the regular consumption of Metformin.
  3. Other benefits: It treats prostate & ovarian cancer, improves fertility in men, improves gut bacteria, prevents dementia, treats PCOD, and enhances lifespan. Thus, has numerous benefits.


Apart from type 2 diabetes management, Metformin tablets are beneficial for weight management, enhancing gut bacteria, PCOD, and prostate and ovarian cancer.

Drug Variants & Brand names:

The drug is available in different doses:

  • Tablet immediate-release: Metformin 500 mg, Metformin 850 mg tablet, Metformin 1000 mg.
  • Extended-release tablet: Metformin 500 mg, Metformin 750 mg tablet, Metformin 1000 mg.
  • As oral solution: Metformin 500 mg, Metformin 750 mg tablet, Metformin 1000 mg.

Brand: Metformin is available under the following different brand names:

Glucophage, Glucophage XR, Fortamet, Glumetza, and Riomet. Read the outer cover for clear manufacturing dates and expiry dates before using the medicine.

How to use Metformin?

Follow the instructions written on the cover of the medicine and as prescribed by the doctor.

  • Take the medicine after your meals to avoid any stomach problems. Therefore the best time is after your food.
  • You should swallow the tablet with a glass of water instead of breaking, crushing, or chewing.
  • For Metformin oral liquid users, a medicine cup is available with the oral syrup. Using the same, you may consume the liquid medicine as per the doctor’s advice.
  • Always, store the medicine in a closed container at room temperature to sustain the effect.

Dosage Instruction

The doses differ from person to person. Follow the below Metformin dosage chart.

Metformin Dosage for type 2 diabetic-Adult

Adult dosage:

  1. Metformin Immediate-release:
    • Initial dose: Metformin 500 mg tablet / twice a day (or) 850 mg / day – oral after meals.
    • Dosage changes: Increase in 500 mg / weekly (or) Metformin 850 mg / every 2 weeks / as per body tolerance. The objective is to have a dose of 2550 mg/day in the divided doses.
    • Maximum dose permitted: 2550 mg/day – oral
  2. Metformin Extended-release:
    • Initial dose: 500-1000 mg / day – oral
    • Dosage changes: Increase in 500 mg/weekly – as per tolerance
    • Maximum dose: Metformin 2000 mg /day – oral – as per toleration

Don’t mix dosage otherwise it shall lead to a drug overdose.

Metformin Dosage – children

Taking metformin medicine for children less than 10 years of age is not advisable. Children above 10 to 18 years can take this medicine. Follow the described Metformin dosage chart to keep in control of your/children’s diabetes.

  1. Metformin Immediate-release:
    • Initial dose: 500 mg / twice a day – oral
    • Dosage titration: Increase in 500 mg / weekly as per tolerance; divided doses 2-3 times/day along with meals
    • Maximum dose: 2000 mg/day – oral
  2. Metformin Extended-release oral suspension:
    • Initial dose: 500 mg/day with evening meal – oral
    • Dosage titration: Increase in 500 mg / weekly / as per glycemic control & tolerance
    • Maximum dose: 2000 mg/day – oral

Don’t mix dosage otherwise it shall lead to a drug overdose.

When to stop or avoid Metformin

  1. Kidney disease: Safely monitoring is essential while using Metformin in patients suffering from mild to moderate kidney disease. Get the eGFR test done before taking Metformin. If eGFR values are less than 30 mL/min/1.73 m² stop the medicine.
  2. Elderly people: People above 80 years of age should avoid this medicine. Elderly people with no history of kidney diseases can take Metformin. But only in case of emergency or in rare cases. And that too for a shorter duration.
  3. Liver disease: Lactic acidosis is a serious side effect of Metformin. Due to Lactic acidosis patients with liver disease conditions would result in serious illness. Thus, avoid Metformin tablets if you have liver disease.
  4. Diabetes ketoacidosis: Metformin will worsen the situation by lactic acid production and thus it should be avoided in diabetes Ketoacidosis.
  5. Heart issues: Any heart issues can get worsen due to lactic acidosis by Metformin. Thus, avoid using this medicine. Otherwise prescribed avoid using with heart disease.

Avoid the medicine if you have any history of medicine allergy.


Patients with kidney disease, heart condition, diabetes ketoacidosis, the liver disease should avoid Metformin tablets.

Side effects of Metformin

This prescribed Metformin drug may lead to common side effects. It may occur during the starting dosage and usually may settle over time. Contact your physician immediately, if any of the following symptoms are severe.

  1. Headache,
  2. Diarrhea,
  3. Constipation,
  4. heartburn,
  5. stomach upset & stomach bloat
  6. nausea & vomiting,
  7. weakness & muscle ache,
  8. infection in the respiratory system.

Warning signs

Consult the doctor immediately if

  • you have swelling of the tongue, face, and throat
  • difficulty in breathing
  • chest discomfort
  • Hives or skin rashes

Metformin Interaction

With other medicines

It has been found that a total of 346 drugs have interaction with Metformin. 19 major drug, 299 moderate, and 28 minor drug interactions have been traced yet.

  • Steroids, diuretics, oral contraceptives, and Estrogens: These drugs have chances of increasing blood glucose level and thus reduce the Metformin effect. So stop these drugs before taking Metformin therapy. After stopping the drugs, the patient should be monitored for any signs of hypoglycemia.
  • H2 blocker, Cimetidine (Tagamet): These have the potential of decreasing metformin elimination from the body. Avoid it before using Metformin. Otherwise, it might lead to frequent side effects.
  • Alcohol consumption: Alcohol intake during Metformin treatment may lead to a serious condition called “lactic acidosis.” Its symptoms are severe muscle pain, feeling chills, breathing trouble, irregular heartbeats, and dehydration. Thus, avoid alcohol when Metformin therapy is on. Otherwise, it can lead to serious complications.

Pregnancy and Lactation

Pregnancy: It is acceptable to use Metformin during pregnancy. Though there are no human-related studies animal studies have proven no risk in taking Metformin tablets during pregnancy. It is better to consult the doctor before taking this medicine during pregnancy.

Lactation: Research has proven that Metformin can pass through the breast milk to the child and thus it is not recommended while breastfeeding the child. Otherwise, it may harm the newborn.

General guidelines

  • Check your blood glucose levels before starting this medicine.
  • Before starting this medicine, it is necessary to have a kidney function test.
  • Avoid the medicine if you have a history of heart disease, liver disease, and kidney disease. Otherwise, it can lead to health complications.
  • Avoid medicine usage in elderly patients above 80 years and children below the age of 9 years.
  • Stop alcohol consumption if you are using Metformin. Otherwise, the situation will worsen.
  • Stop the Metformin therapy before undergoing any surgery.
  • It is advised to stop the Metformin medicine before any Iodinated contrast imaging procedures.
  • Metformin can reduce calcium absorption and Vitamin B12 in the body. If you have any of these deficiencies stop taking Metformin.
  • It is required to drink plenty of fluids and liquids while taking this medicine.
  • Doing heavy exercise, skipping meals along with Metformin can lead to hypoglycemia. Check blood glucose levels before taking the medicine.
  • Store the medicine in a safe place away from children reach the temperature of 20°C and 25°C.

Bottom line:

On the whole, Metformin tablets are a popular option for type 2 diabetes management. It is predominantly prescribed by Doctors as the best way to control weight and type 2 diabetes. But it is essential to have a healthy lifestyle, a good diet plan along with this medicine to control and reverse type 2 diabetes. Continue your diabetic medication and stay healthy.


Why am I asked to take Vitamin B 12 supplements with Metformin?

Metformin decreases Vitamin B12 levels in the body. Thus, doctors may recommend having additional supplements of Vitamin B 12 and calcium with Metformin.

Can I take Metformin if I have type-1 diabetes?

Metformin is an effective drug in the management of type 2 diabetes. Its usage in type 2 diabetes is not clinically proven.

What is the best time to take Metformin?

Since Metformin can cause problems like stomach upset it is advised to take it after meals. This shall reduce bowel problems and other gut-related problems. While extended-release Metformin should be taken at the night after dinner.


  1. Rena, G., Hardie, D. G., & Pearson, E. R. (2017). The mechanisms of action of metformin. Diabetologia, 60(9), 1577-1585.
  2. Sharabi, K., Tavares, C. D., Rines, A. K., & Puigserver, P. (2015). Molecular pathophysiology of hepatic glucose production. Molecular aspects of medicine, 46, 21-33
Last Updated on by Dr. Damanjit Duggal 


The information included at this site is for educational purposes only and is not intended to be a substitute for medical treatment by a healthcare professional. Because of unique individual needs, the reader should consult their physician to determine the appropriateness of the information for the reader’s situation.

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