Side Effects of Metformin

Side Effects of Metformin

Metformin can cause side effects in some people. Side effects of Metformin are mild and serious, and they depend on the person. They also depend on factors that put you at risk for developing side effects.

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1 Side Effects of Metformin

Recall of metformin extended-release.

The Food and Drug Administration advised some metformin extended-release tablet producers to remove some tablets from the market in May 2020. This is due to an untoward level of a potential carcinogen (cancer-causing agent) discovered in some long-acting metformin tablets. If you are currently taking this medication and have questions, contact your physician to discuss the risks and benefits.

Metformin is a type 2 diabetes medication. It’s a kind of biguanide drug that belongs to the class of medications called binder medicines. People with type 2 diabetes have higher than normal blood sugar levels. Metformin does not cure diabetes; instead, it helps to keep your blood sugar levels in the target range. The first dose of Metformin is usually taken right before breakfast on an empty stomach or with a light meal that contains only a moderate amount of fat.

Long-term use of Metformin is required. This might lead you to ask whether there are any adverse effects involved. Metformin has both minor and severe adverse effects, which are the same for both men and women. Here’s what you need to know about them and when to contact your doctor.

Common side effects of Metformin you should know about

Metformin has the following potential adverse effects. These might occur when you start taking Metformin, but they generally subside with time. If these symptoms are too severe or uncomfortable for you, tell your doctor.

Common side effects of Metformin are:

  • stomach pain
  • heartburn
  • unpleasant metallic taste in the mouth
  • nausea or vomiting
  • gas
  • diarrhea
  • weight loss
  • bloating
  • headache
  • constipation

Metformin comes with several possible side effectsthe most common of which include nausea, vomiting, and diarrhea. These issues generally go away on their own after a while. To ease the discomfort associated with Metformin, take it with food. Also, your doctor will most likely start you off on a low dose of Metformin and gradually increase it to minimize your risk of severe diarrhea.

Metformin is occasionally used to treat diabetes in women with polycystic ovarian syndrome (PCOS). It’s being used off-label for this purpose. The adverse effects of this usage are comparable to those seen with other applications.

Side Effects of Metformin

Serious side effects of Metformin

Lactic acidosis

Lactic acidosis is the most severe but uncommon side effects of Metformin. This danger is mentioned in a “boxed” — also known as a “black box” — alert on Metformin. The FDA issues a boxed warning only when the danger is severe.

Lactic acidosis is a rare but dangerous condition that can occur due to metformin buildup in the body. It’s a medical emergency that must be handled right away in the hospital.

You may be at risk of lactic acidosis if you have any of the following:

If you think you have lactic acidosis, contact your doctor right away. If breathing is difficult, call 911 immediately or go to the closest emergency department.

  • weakness
  • trouble breathing
  • decreased appetite
  • feeling cold
  • flushing or sudden reddening and warmth in your skin
  • vomiting
  • nausea
  • dizziness
  • lightheadedness
  • muscle pain
  • extreme tiredness
  • a fast or slow heart rate
  • stomach pain with any of these other symptoms


Metformin can reduce your body’s vitamin B-12 levels. This might lead to anemia, or low red blood cell counts in a few people. If you don’t get enough vitamin B-12 or calcium from your diet, you may be more likely to have deficient vitamin B-12 levels.

If you stop taking Metformin or use vitamin B-12 supplements, your vitamin B-12 levels may improve. Do not cease taking Metformin without consulting with your doctor first.

The more common symptoms of anemia include:

  • dizziness
  • tiredness
  • lightheadedness

Make an appointment with your doctor if you believe you have anemia.


Metformin does not cause blood sugar levels to become too low when taken alone. However, if you take Metformin along with any of the following factors, you may develop hypoglycemia:

  • a poor diet
  • dizziness
  • excessive alcohol intake
  • strenuous exercise
  • other diabetes medications

If you have any signs or symptoms of hypoglycemia, contact your doctor right away. Symptoms of hypoglycemia include:

  • stomach pain
  • tiredness
  • lightheadedness
  • vomiting
  • weakness
  • nausea
  • dizziness
  • abnormally fast or slow heartbeat


Metformin increases your risk of developing lactic acidosis, which is a severe condition. If any of these factors apply to you, talk with your doctor before starting metformin therapy.

Kidney problems

Metformin is eliminated from your body by your kidneys. If your kidneys cannot function, Metformin will be present in your system in more significant quantities. Lactic acidosis is a heightened danger as a result of this.

Your doctor may start you on a lower dose of Metformin if your kidney function is normal or only mild or moderate kidney problems exist.

Metformin may not be appropriate for people with severe kidney problems or 80 years old or older. Your doctor will likely check your kidney function before and after starting Metformin to see if it works.

Heart problems

If you have had a heart attack or are experiencing acute heart failure, you should not take Metformin.

Your heart’s failure to pump adequate blood may result in your kidneys not receiving enough. As a consequence, your kidneys will be unable to remove Metformin from your body as effectively as they would otherwise, increasing the risk of lactic acidosis.

Liver problems

If you have severe liver problems, you should not take Metformin. Your liver removes lactic acid from your circulation.

Lactic acid accumulation can cause severe liver issues. Lactic acidosis is a disease that develops as a result of lactic acid buildup. Metformin, like other diabetes medications, raises the risk of lactic acidosis.

Alcohol use

When you drink alcohol while taking Metformin, your risk of hypoglycemia rises. It also raises the danger of lactic acidosis. This occurs since it boosts lactic acid levels in the body.

While taking Metformin, you should not drink large amounts of alcohol. Long-term alcohol drinking and binge drinking are examples of this. If you consume alcoholic beverages, consult your doctor about how much is safe for you while taking Metformin.

People with diabetes should be careful before they drink alcohol. Drinking can make it harder for them to control their blood sugar levels. Read more about the dangers of drinking with metformin use and how alcohol affects diabetes.

Surgical or radiologic procedures

If you have an upcoming surgical or radiology procedure that will utilize iodine contrast, your doctor should tell you to cease taking Metformin for 48 hours beforehand.

The use of ribavirin and other antiviral medications, and various chemotherapy drugs can cause toxic metformin levels when combined. Since these treatments might slow the removal of Metformin from your body, increasing your risk of lactic acidosis, you should resume taking it only after your kidney function tests are normal.

Talk with your doctor about the side effects of Metformin

If you’re on Metformin and concerned about the risks, consult with your doctor. You might want to have a look at this article with your doctor. Make sure to ask any questions you may have, such as:

  • What kind of adverse effects should I be concerned about?
  • Is my risk of developing lactic acidosis high?
  • Do I have an alternative medication to try that might have fewer adverse effects?

Your doctor can address your concerns and assist you with any side effects of Metformin you are experiencing.

Side Effects of Metformin

Metformin Side Effects Question and Answers

Why do doctors no longer prescribe Metformin?

In 2020, the FDA recommended that some makers of Metformin remove their tablets from the U.S. market because an unacceptable level of a probable carcinogen (cancer-causing agent) was found in some extended-release metformin tablets.

Should I be worried about taking Metformin?

The medication can cause more severe side effects, though these are rare. One of the most severe side effects is lactic acidosis, caused by too much Metformin accumulates in your body. This can happen if you have chronic or acute kidney problems and don’t drink enough water to help get rid of the medicine.

What does Metformin do to the body?

Metformin can be used to control your blood sugar levels when diet and exercise are not enough. Women who have PCOS may also need Metformin because it can lower insulin and blood sugar levels, which helps with ovulation.

Why was Metformin taken off the market?

The FDA recalls Metformin because it might be contaminated with nitrosodimethylamine (NDMA), more than the acceptable intake limit. The FDA has a list of all the medicines that have been recalled and what they were contaminated with.

What is the bad news about the side effects of Metformin?

Rarely, Metformin can cause lactic acidosis. This is when there is too much of a chemical in the blood called lactic acid. It can lead to low blood pressure, rapid heart rate, and even death. Vomiting and dehydration make it more likely that people will get this side effect while taking Metformin.

How long can you stay on Metformin?

The American Diabetes Association recommends that people with prediabetes take Metformin. It is usually a long-term medication unless you have changes to your health.

Who should not use Metformin?

Your doctor will tell you not to take Metformin. They might say this if you are over 65 years old or have ever had a heart attack, stroke, diabetic ketoacidosis (if your blood sugar is high), coma, or heart disease.

Does Metformin reduce belly fat?

Metformin does not have a significant effect on visceral fat mass, although it does improve lipids. This study adds weight to the growing body of evidence showing that Metformin is not a weight-loss medication.

What are the dangers of taking Metformin?

Common side effects of Metformin include diarrhea, nausea, vomiting, and flatulence. Other side effects include: feeling weak and decreased levels of vitamin B12 in the blood.

Can I stop taking Metformin when my sugar is back to normal?

Metformin may help you with long-term complications from type 2 diabetes. But your doctor can tell if it is safe for you to stop taking it.

Is there a good substitute for Metformin?

NICE has advised three new treatment options for people with type 2 diabetes who can’t tolerate Metformin, sulfonylurea, or pioglitazone. The therapies are also appropriate for those who aren’t managing their blood sugar levels through diet and exercise alone to control their disease.

Is Metformin safe now?

If you’re currently taking Metformin I.R., you may continue to take it. The FDA has not discovered high NDMA levels in the most often prescribed immediate-release (I.R.) Metformin preparations. Metformin is a medicine often used to help individuals with type 2 diabetes control their blood sugar levels.

Side Effects of Metformin

Can Metformin cause a stroke?

In individuals with type 2 diabetes undergoing hemodialysis, metformin use was linked to a greater incidence of ischemic and hemorrhagic strokes (ischemic and hemorrhagic stroke) in comparison to nonusers, regardless of antihypertensive, sulfonylurea, or antiplatelet medication use.

What should you not eat when taking Metformin?

Avoid eating high-fiber meals after taking Metformin, according to the University of Michigan. This is because fiber can bind with medications and lower its concentration. When Metformin is combined with a lot of fiber (more than 30 grams per day), its levels fall significantly.

When Should Metformin be stopped?

Metformin should be stopped when your kidney function falls below 30 ml/min/1.73 m2. When your kidney function is between 30 and 60 ml/min/1.73 m2, you should lower the dose of Metformin you take.

Can Metformin damage your liver?

Metformin does not appear to cause or exacerbate liver damage, and it is frequently helpful in those with nonalcoholic fatty liver disease. The nonalcoholic fatty liver disorder commonly features elevated transaminases but should not be considered an obstacle to metformin therapy.

How long does 500mg of Metformin last?

It takes roughly four days for the drug metformin (Glucophage) to leave your system. Metformin has an elimination half-life of 17.6 hours.

What should I eat while taking metformin?

Consume a variety of real foods, such as fruits, vegetables, and grains. Processed meals should be avoided. Eat a diet high in protein and low in fat.

What is the best time of day to take metformin?

Metformin is available as a tablet or injectable form. It’s usually taken twice or three times daily. To reduce the stomach and bowel adverse effects that may occur, take it with meals – most people take metformin with breakfast and dinner. Metformin ER is taken once a day and should be taken at night, after eating.

What is the benefit of taking metformin at night?

Metformin, when taken at bedtime instead of supper time, may help with diabetes management by decreasing afternoon hyperglycemia.

Does metformin keep you awake at night?

One of the reported side effects of Metformin is sleep difficulties, especially insomnia.

What happens if you take metformin without food?

Metformin does not cause insulin release, so although there is a small danger of hypoglycemia if taken without food, it is much lower than that incurred by other anti-diabetic medications. Metformin can, however, boost the risk of hypoglycemia when used with other antidiabetic drugs.

Do you need to drink a lot of water with metformin?

To help reduce stomach or bowel discomfort that may occur during the first few weeks of treatment, Metformin should be taken with meals. The tablet or extended-release tablet should be swallowed whole with a full glass of water. It should not be crushed, broken, or chewed.

Can I stop metformin cold turkey?

Metformin is important for diabetes treatment. But it can be safe to lower the dosage or stop taking metformin altogether if your diabetes is under control.

Can metformin affect mood?

Chronic metformin treatment for 24 weeks improved cognitive performance as assessed by the Wechsler Memory Scale-Revised in persons with T2DM who were depressed. Furthermore, metformin significantly enhanced depressive performance and altered glucose metabolism in people with diabetes.

Can metformin cause a stroke?

Studies show that one of the side effects of Metformin in hemodialysis patients with type 2 DM, users had a significantly higher risk of stroke (ischemic and hemorrhagic stroke) than nonusers, regardless of antihypertensive, sulfonylurea, or antiplatelet drug use.

Side Effects of Metformin Resources

Here are some side effects of Metformin links to further assist with your diabetes planning.

U.S. National Library of Medicine – National Institutes of Health – Side Effects of Metformin Tablet

The severity of Gastrointestinal Side Effects of Metformin Tablet Compared to Metformin Capsule in Type 2 Diabetes Mellitus Patients

Cleveland Clinic Consult Q.D. – Possible Side Effects of Metformin Use in Patients with Type 2 Diabetes 

Metformin should be considered in all adult patients with type 2 diabetes; gradual titration and extended-release formulation should reduce adverse side effects of Metformin.

WebMD – Metformin Side Effects: Management and Who’s at Risk 

Metformin is a standard diabetes treatment. But it can cause digestive problems and other side effects. Learn more about the common, serious, and rare side effects of Metformin, who’s at risk, and how to manage them. – Metformin Side Effects

List of side effects of Metformin divided by how often they occur from very common side effects to rare side effects and what you should do if you experience any side effects related to Metformin. – Metformin Side Effects: Common, Severe, Long Term

Learn about the potential side effects of Metformin. Includes common and rare side effects information for consumers and healthcare professionals.

Medical News Today – Metformin: Side effects, dosage, uses, and more

Metformin oral tablet is a prescription drug used along with diet and exercise to treat high blood sugar levels caused by type 2 diabetes. Tablets are available as generic drugs and brand-name drugs Glucophage, Glucophage XR, Fortamet, and Glumetza. Learn about side effects of Metformin, warnings, dosage, and more

Women’s Health – 5 Metformin Side Effects To Watch Out For – What Is Metformin? 

Metformin is a medication developed to treat Type 2 diabetes that can also aid in weight loss. Here are some common side effects OF Metformin, like diarrhea and lactic acidosis.

The GoodRx – Long-Term Side Effects of Metformin: What Are the Risks?

Metformin is one of the most common first-line treatments for type 2 diabetes and prediabetes. Long-term side effects of Metformin are generally minimal and manageable.

Diabetes Strong – Metformin Side Effects: What You Need to Know

Metformin is one of the most prescribed drugs on the planet, but the side effects can be brutal. Here’s what you can do to avoid the side effects of Metformin.

Roman HealthGuide – What are the most common side effects of Metformin?

The most common side effects of Metformin are gastrointestinal issues, such as nausea, diarrhea, vomiting, heartburn, loss of appetite, stomach pain, stomach upset, and a metallic taste in the mouth.

Single Care – Metformin side effects and interactions, and how to avoid them

Upset stomach and weight loss are some side effects of Metformin. Compare common, serious, and long-term side effects of Metformin and learn how to avoid them.

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