Side Effects And Risks Of Taking Metformin: You Should Know!


Most of us suffer from the nagging problem of high blood sugar levels. When it comes to controlling those excessively high blood sugar levels, metformin, a biguanide drug, has come as a blessing. However, the hard truth is that many of us are unaware of the side effects caused by metformin. In this article, we explain metformin, its uses, dosage, side effects, and warnings.

What is metformin? Benefits And Side Effects

Benefits of metformin

Metformin is an antidiabetic agent approved by the U.S. Food and Drug Administration in the treatment of diabetes mellitus or sugar diabetes, also known as type 2 diabetes. The problem with this type of diabetes is that insulin produced by the pancreas will not be able to get sugar into the body's cells where it can function efficiently.

Metformin comes in both immediate- and extended-release formulations and is generally used in combination with other antidiabetic agents. The medication works in such a way that it aids in lowering blood sugar when the levels are too high. Moreover, Metformin helps restore the way we use food to produce energy. 

This medication also holds the distinction of being the only antidiabetic medication available for prediabetes that is recommended by the American Diabetes Association (ADA).

Benefits of metformin

The following are the major benefits of consuming metformin.

1. Prediabetes

Apart from helping in lowering diabetes, metformin also helps people with prediabetes. Prediabetes is a condition in which people have elevated blood sugar levels, but it is not so high to qualify as diabetes. Metformin helps those with prediabetes by delaying the occurrence of diabetes or even preventing it.

2. Gestational diabetes

Among pregnant women, blood sugar levels may shoot up and it will return to normal post-delivery. In such cases, metformin helps control blood sugar.

3. Weight gain caused due to antipsychotic medicines

People with psychiatric diseases such as schizophrenia generally take antipsychotics which are medications used in their treatment. As a result, they may gain weight significantly and metformin helps reduce weight gain among such people.

4. Polycystic ovary syndrome (PCOS)

Menstrual irregularities and fertility problems are commonly found among people with PCOS. For a long time, metformin has been prescribed for such patients as it helps with fertility, menstrual regulation, and a rise in blood sugar.

Uses of Metformin

Apart from the benefits mentioned in the above section, metformin also offers cardiovascular benefits for people suffering from diabetes. A major advantage is that the medication lowers death rates due to cardiovascular disease. Last, but not least, metformin also helps people with diabetes shed extra weight.

Precautions of metformin

  • Metformin should be stored at room temperature.
  • It is best recommended to keep the medication away from moisture or heat. Thus, places such as bathrooms should be avoided.
  • Keep Metformin away from kids.

Dosage of metformin

  • We have to take metformin with meals so that it will aid in reducing stomach or bowel side effects that one may experience during the first few weeks of treatment.
  • The right method is to take the tablet or extended-release tablet whole and swallow it with a full glass of water. We should refrain from crushing, chewing, or breaking it.
  • While taking the extended-release tablet, part of it may pass into the patient’s stool after his/her body has absorbed the medicine. This is normal and we don’t have to worry about it.
  • The oral liquid needs to be measured by using an oral syringe, marked measuring spoon, or medicine cup. A supplied dosing cup can be used to measure the mixed extended-release oral suspension.
  • We should use only the same brand prescribed by the doctor.
  • Within 1 to 2 weeks, we can notice an improvement in blood glucose control. However, to reap the full benefit of blood glucose control, it may take up to 2 to 3 months.

Metformin side effects Long-Term

The common side effects of using metformin may range from feeling sick (nausea), diarrhea, being sick (vomiting) to loss of appetite, stomach ache, and a metallic taste in the mouth. When it comes to the ratio of side effects, it is generally more than 1 in 100 people.

Gastrointestinal Issues

  • Nausea: Some people may experience mild nausea, especially when starting the medication.
  • Diarrhea: This is a common side effect, particularly at the beginning of treatment. It may improve over time or with dosage adjustments.

Digestive Discomfort

  • Abdominal pain: Some individuals may experience discomfort or cramping in the abdominal area.
  • Flatulence: Increased gas production can occur in some cases.

Taste Disturbances

  • Metallic taste: A metallic or unpleasant taste in the mouth has been reported by some individuals.

Decreased Vitamin B12 Absorption

  • Vitamin B12 deficiency: Long-term use of metformin may lead to reduced absorption of vitamin B12, potentially causing deficiency. Periodic monitoring of B12 levels may be recommended.

Lactic Acidosis (Rare)

  • Lactic acidosis: Although rare, metformin can lead to a serious condition called lactic acidosis. This is more likely to occur in individuals with kidney or liver problems. Symptoms include muscle pain, weakness, trouble breathing, and abdominal discomfort. Seek medical attention immediately if you experience these symptoms.

Hypoglycemia (Low Blood Sugar)

  • Hypoglycemia: Metformin itself does not typically cause low blood sugar, but when combined with other diabetes medications that do, it can increase the risk of hypoglycemia.

It's important to follow your healthcare provider's instructions regarding the dosage and administration of metformin. Additionally, inform your healthcare provider about any other medications or supplements you are taking, as they can interact with metformin.

If you experience severe or persistent side effects, contact your healthcare provider promptly. They can adjust your dosage or explore alternative treatment options if necessary. Remember that this information is not exhaustive, and individual responses to medications can vary. Always consult with your healthcare provider for personalized advice.

Final Thoughts

Curbing high blood sugar levels is no doubt a challenging problem. Thus, metformin has become a boon for millions of patients suffering from elevated blood sugar levels. However, as discussed in the above sections, we also need to be aware of the metformin side effects and follow the instructions carefully before we start to use the medication.


1. Who should not use metformin?

Metformin is not recommended for elderly people who are 80 years of age and above and have been diagnosed with kidney problems. The other categories who should not use the medication include those who had an allergic reaction to metformin or other medicines in the past, have liver problems, have uncontrolled diabetes, undergoing treatment for heart failure, or have recently had a heart attack, experiencing problems with circulation or breathing difficulties and heavy alcoholics.

2. How soon after taking metformin do you feel better?

Metformin may lower blood sugar levels within a week of starting the treatment. However, for the patient to experience the full effects, it will take a couple of months.

3. What foods to avoid while taking metformin?

Avoid foods containing refined/processed carbohydrates including white rice, white bread, soda, candy, and white pasta. Saturated fats such as red meat, cheese, and butter should also be avoided. The other foods to stay away from include items that contain lots of sodium such as pre-packaged snacks, fast food and canned soups, and sugar-sweetened soda, chips, cakes, chocolates, crackers, ice cream, and foods containing transfats i.e. fast food and baked goods from stores.

4. How long do side effects last?

 The metformin side effects are short-term in nature. They may last for 2 weeks or less.

5. Is metformin safe to take?

The safety profile for the medicine is pretty good. Though there may be mild side effects such as the ones discussed above, cases of serious side effects are rare.


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Dr. David G Kiely is a distinguished Medical Reviewer and former General Medicine Consultant with a wealth of experience in the field. Dr. Kiely's notable career as a General Medicine Consultant highlights his significant contributions to the medical field.

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