What Are The Common Side Effects of Metformin in Diabetics?

Metformin is a prescription drug which is used in treatment of type 2 diabetes. It hails from biguanides, a class of medications. In type 2 diabetes, blood glucose levels go higher than normal. Metformin helps control blood sugar levels at a normal range, rather than curing diabetes.

It is prescribed for the long term. Metformin can cause common to rare side effects which are same in both sexes. Read on to know about its common and rare side effects and when to call the doctor.

Common Side Effects

There are some common side effects of Metformin which can take place when you first take it and usually go away with time. If you have one of these symptoms that cause a problem or are severe for you, be sure to ask your doctor. Here are some of the common side effects –

  • Stomachache
  • Heartburn
  • Vomiting or nausea
  • Gas
  • Bloating
  • Diarrhea
  • Unusual weight loss
  • Constipation
  • Headache
  • Weird metallic taste on mouth

Rare Side Effects


Metformin can lower the level of vitamin B12 in the body. It can lower the levels of red blood cells and cause anemia in rare cases. If you don’t get much calcium or vitamin B12 in your diet, you might be at huge risk of low vitamin B12. Vitamin B12 levels may improve if you take vitamin B12 supplements or stop taking Metformin. Ask your doctor before you stop taking it. Here are some of the common symptoms of anemia

  • Fatigue
  • Lightheadedness
  • Dizziness

Be sure to fix an appointment with the doctor if you feel that you have anemia.

Lactic Acidosis

It is one of the most critical side effects of metformin. It has a caution on the box which is more serious from the Food & Drug Administration (FDA). It is a serious yet uncommon problem which can take place because of buildup of this drug in the body. You should go to the hospital right away because it is a medical emergency. If you any one of these symptoms, call your doctor or 911 if you have trouble in breathing –

  • Weakness
  • Severe tiredness
  • Reduced appetite
  • Vomiting
  • Nausea
  • Dizziness
  • Trouble breathing
  • Slow or fast heart rate
  • Lightheadedness
  • Muscle pain
  • Feeling chilled
  • Stomach pain with other symptoms above
  • Flushing (sudden warmth or redness to your skin)


Metformin alone doesn’t cause low blood sugar or hypoglycemia. But you may develop it in rare cases by combining it with –

  • Strict exercise
  • Poor diet
  • Excessive consumption of alcohol
  • Other diabetes drugs

To prevent hypoglycemia

  • Go through a well-balanced diet
  • Take your medications timely.
  • Exercise as per the directions by the doctor.
  • Ask your doctors about all medications you take

If you any of these hypoglycemia symptoms, call your doctor

  • Vomiting
  • Weakness
  • Fatigue
  • Nausea
  • Dizziness
  • Stomach pain
  • Unusually slow or rapid heartbeat
  • Lightheartedness


There are different factors increasing the risk of lactic acidosis while taking Metformin. If one of these factors affecting you, feel free to contact your doctor before taking this medication.

Liver Problems

Skip taking metformin if you are suffering severe liver problems. Your liver removes lactic acid from the body. Hence, severe liver problems could cause buildup of lactic acid. It raises the risk of lactic acidosis.

Heart Issues

If you had a heart attack recently or acute heart failure, don’t take metformin. Your heart might be unable to send proper blood to your kidneys. It would keep your kidneys from removing this drug from the body and normally increase the risk of lactic acidosis.

Alcohol abuse

If you combine metformin with alcohol use, it can increase the risk of hypoglycemia. It increases the levels of lactic acid in your body and also the risk of lactic acidosis. If you consume alcohol, ask your doctor on how much is safe for you while taking metformin.

Kidney issues

Metformin is removed by kidneys from the body. If kidneys stop working, you will suffer higher levels of metformin in your body. It increases the risk of lactic acidosis. If you have moderate or mild kidney issues, your doctor may recommend lower dosage of it. If you are above 80 years or severe kidney issues, this drug may not be suitable for you. Your doctor will test your kidney function before taking it.

When to Talk to Your Doctor?

If your doctor has prescribed this medication, and you are worried of its side effects, ask your doctor. You may ask questions like –

  • Is there high risk of lactic acidosis?
  • What side effects to be more careful with?
  • Is there any other alternative to have fewer side effects?

Your doctor will answer these questions and may work with you to deal with any side effects you may suffer.

[su_spoiler title=”References” style=”fancy” icon=”plus-circle”]

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  • https://www.healthline.com/health/diabetes/metformin-side-effects#serious-side-effects



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