Metformin Side Effects

Metformin can improve glucose levels in type 2 diabetes. It’s safe and effective for most people, but you should know about possible metformin side effects.

If you’ve been diagnosed with type 2 diabetes, you aren’t alone. Nearly 40 million Americans have diabetes, and the majority, about 95 percent, have type 2, according to the Centers for Disease Control and Prevention. While diet and exercise may be enough to control and even improve type 2 diabetes, medication is necessary for many people — and metformin is most common doctors prescribe.

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Metformin is an oral diabetes drug used to improve blood sugar (also called blood glucose) levels and reduce the health risks associated with type 2 diabetes. Although metformin, along with exercise, diet, and careful monitoring of blood sugar, is often enough to manage type 2 diabetes, sometimes the drug is used with insulin or other medications (however, it is not a treatment for type 1 diabetes).

Although it’s considered generally safe, effective, and the first-line treatment for type 2 diabetes, metformin, like any drug, has a risk of side effects. Recognizing metformin side effects, and learning about how to reduce the odds you’ll experience any significant ones, is part of sensible self-care for anyone with type 2 diabetes.

Avoiding common metformin side effects

Metformin is a prescription medication that comes in pill, regular and long-acting, and liquid forms (sold as Fortamet, Glucophage, Glucophage XR, Glumetza, Riomet, among others). It’s important to discuss any concerns you have about dosages and possible side effects with your doctor or pharmacist — and always read and follow the patient instructions that come with your medication.

Tell your doctor or pharmacist about any other drugs, over-the-counter medications, and supplements you take. Those products may affect how well metformin works and may cause side effects when combined with the diabetes drug.

Some of the most common metformin side effects, which may go away over time, include:

• Nausea
• Upset stomach
• Abdominal discomfort
• Belching
• Bloating
• Diarrhea

You can take metformin with food to avoid those gastrointestinal (GI) side effects. In addition, ask your doctor about using an extended-release formulation, which may reduce GI side effects.

Metformin lowers blood glucose. But when it’s combined with alcohol, blood sugar tends to fall very quickly, potentially plummeting too low. The result can be hypoglycemia — low blood sugar with symptoms such as dizziness, shakiness, heart palpitations, and feeling faint.

To avoid those side effects of metformin, you can abstain from alcohol. If you don’t, the American Diabetes Association recommends consuming alcohol with food and limiting the amount you drink — no more than one daily for women and two for men.

Less common side effects

Metformin symptoms may also include these less frequent side effects:

• Flu-like symptoms
• Joint pain
• Rash
• Runny nose and sneezing
• Swollen joints and difficulty moving
• Discolored fingernails or toenails
• Dizziness or confusion
• Irregular heart rhythm
• Blurred vision

 If you have those, or any other new symptoms, contact your doctor immediately.

The most serious side effects

Although rare, lactic acidosis can be a side effect of taking metformin. It occurs when excess lactic acid builds up and your body can’t metabolize it quickly enough. The condition can be a life-threatening emergency, requiring immediate medical care.

The risk of lactic acidosis is highest for people with kidney disease and other types of dysfunction, along with advanced age. You can have your renal function checked regularly and take the minimum effective dose of metformin to lower your risk.

While the odds of having lactic acidosis from taking metformin are low, the condition does occur and, because lactic acidosis is fatal about 50 percent of the time, it’s crucial to know the symptoms.

The onset of lactic acidosis is often marked by nonspecific symptoms that can be subtle and overlooked at first, including:

• Fatigue
• Muscle aches and pains
• Shortness of breath
• Increasing sleepiness
• Abdominal pain

The condition can develop either rapidly, within minutes or hours, or gradually over several days.

As the condition grows worse, low blood pressure, an abnormally low body temperature, and slow heartbeat typically occur. The Food and Drug Administration advises anyone taking metformin to be aware of these symptoms and to contact your doctor immediately if you experience them.

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