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Drug Side Effects

Metformin Side Effects For PCOS: 6 Things You Need To Know

Oct 6, 2017

Insulin resistance is seen in the majority of women with PCOS. Doctors prescribe metformin for PCOS because it is an effective insulin sensitizer. However, the drug comes with its share of side effects. Let’s look at Metformin side effects for PCOS in detail.

Metformin Side Effects For PCOS

1. Malaise Or Physical Discomfort

As many as 1 in every 4 women on metformin just does not feel well. There is a feeling of fatigue even without much physical exertion. Sometimes, this fatigue is accompanied with aches that can last for a varying degree of time. While this may not sound too severe, it is one of the most common Metformin side effect for PCOS.

2. Gastrointestinal Distress

Gastrointestinal problems is another common Metformin side effect for PCOS (experienced by nearly a third of women taking the drug.) These problems include abdominal pain, nausea, occasional vomiting, loose motions, irregular bowel movements or diarrhea. Bloating and flatulence can be a major source of embarrassment. Anorexia and a sharp metallic taste can play havoc with appetite, especially because eating a healthy diet at the right times is critical for PCOS patients. Heartburn and headaches add to the suffering caused by PCOS symptoms.

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3. Anemia

Another Metformin side effect for PCOS is a decrease in Vitamin B12 levels because the drug affects the absorption of this vitamin. Vitamin B12 is vital for red blood cell formation. When levels of vitamin B12 go down, you can suffer from anemia. Common symptoms of anemia include tiredness, lightheadedness, and dizziness. Vitamin B12 also plays an important role in many bodily processes. For example, there is evidence of a relationship between low levels of vitamin B12 and an increased risk of heart diseases.

4. Accumulation Of Homocysteine

Long-term use of metformin f0r PCOS causes a decrease in the levels of folic acid (vitamin B9). This causes an increase of an undesirable compound called homocysteine. The accumulation of homocysteine is linked to increased risk of colon cancer, stroke, recurrent miscarriage, Alzheimer’s disease, depression and heart disease. Low levels of vitamin B12 and folic acid along with high levels of homocysteine are also harmful to the health of a developing baby.

5. Lactic Acidosis

One of the rare, yet serious, side effect of using metformin for PCOS is lactic acidosis. This condition occurs when lactic acid accumulates in the body. As a result, the blood becomes highly acidic. If the acid levels go too high, it is a medical emergency and the patient has to be moved to an ER. They need to be treated right away failing which she can go into a coma and probably die.

Symptoms of lactic acidosis include

  • Extreme tiredness
  • Weakness
  • Nausea
  • Vomiting
  • Loss of appetite
  • Trouble breathing
  • Dizziness
  • A fast or slow heart rate
  • Muscle pain
  • Flushing
  • Stomach pain

6. Low Blood Sugar

Taking metformin alone for PCOS does not cause hypoglycemia or low blood sugar. However, metformin, when accompanied with an unhealthy lifestyle, can lead to hypoglycemia. If you eat a poor diet, consume excessive alcohol, or perform strenuous exercises, you are at a risk of becoming hypoglycemic.

Symptoms of hypoglycemia include

  • Weakness
  • Nausea
  • Vomiting
  • Stomach pain
  • Dizziness
  • Lightheadedness
  • Abnormally slow or fast heartbeats


Metformin was introduced as a “miracle drug” for diabetes a few decades back. In studies on PCOS patients, it also showed an impact on other than what it was intended for. This sparked interest in the use of metformin for treating the various symptoms of PCOS. However, the side effects of Metformin for PCOS, although few, can be a cause for worry.

The best way to treat PCOS from its roots is a change in diet and lifestyle along with effectively managing stress and a targeted exercise regimen.

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Jitendra Rathod
Jitendra is a microbiologist and a passionate student of the human body. He is a firm believer in the power of alternative and holistic medicine. He believes nature holds the key to restore us back to health and balance.