The 4 Side Effects of Metformin (Glucophage)

Metformin has very few serious side effects. In our opinion, metformin is, for most people, safer than other blood sugar-lowering drugs. For example, metformin does not cause weight gain. Unlike glyburide (Diabeta), metformin will not cause severe hypoglycemia or weight gain. (Note: Medications like Sitagliptin (Januvia) and Liraglutide (Victoza) don’t cause hypoglycemia or weight gain either,  but metformin does a better job of preventing heart disease).

What Are the Side Effects of Metformin (Glucophage)?

Metformin is not free from side effects, however. Rarely, metformin may cause lactic acidosis. Lactic acidosis is a life-threatening condition. Know the signs & symptoms: troubled breathing, unusual stomach pain, excessive sleepiness, malaise and vomitting.  You’re more likely to experience lactic acidosis if you have chronic kidney disease, severe liver damage or severe heart failure.

Metformin can also cause B12-deficiency anemia. A history of B12 anemia, a vegan diet and old age will increase your risk of getting anemia.

The most common side effects of metformin are nausea and vomiting. Fortunately, these side effects are self-limiting. That is, in most cases, your body will learn to tolerate these side effects.

Is Metformin (Glucophage) Safe for Pregnant Women & Nursing Mothers?

High blood sugar is a danger to the fetus.

If you’re pregnant, or thinking about getting pregnant, please switch to insulin. Insulin will better and faster control of your blood sugar. If you are unable to take insulin, glyburide (Diabeta) may be a safer option than metformin.

Metformin likely does not contaminate breast milk.

Pharmacist’s Tips

  • Use the following 2 simple rules to avoid the nausea and vomiting caused by metformin :
    • Start Low – Start your diabetes treatment at a very low dose (i.e. 250mg metformin once daily). If you develop nausea or vomiting, lower your dose.
    • Go Slow – Once your body develops a tolerance, increase your dose of metformin slowly. For example, if your doctor wants to increase your dose from 500mg twice daily to 500mg three times daily, add 125-250mg of metformin every 3-7 days.
  • A dose greater than 1500mg/day rarely provides additional benefit. Such a dose does cause more side effects, however. So, if you’re taking more than 1500mg of metformin daily, and your A1C is still not under control, you should either lose weight or add another diabetes drug. Don’t increase your dose or metformin.
  • Metformin causes anemia by lowering your B12 levels. Low B12 levels causes lower hemoglobin levels. So, get your hemoglobin and/or B12 checked every 6-12 months.
  • Talk to your pharmacist before taking ranitidine (Zantac) with metformin. Zantac may increase the amount of metformin in your body, and increase your risk of metformin side effects.

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