While you won't have withdrawal, the effects of stopping metformin include the complications linked to uncontrolled diabetes, from fatigue to nerve damage.

Metformin is primarily prescribed to help lower blood sugar levels in people with prediabetes and type 2 diabetes. It does its job so well that the American Diabetes Association (ADA) considers it a first-line diabetes drug, meaning that it is both effective and has relatively few side effects 410.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

However, some people do experience adverse effects, or develop another medical reason to stop taking the medication. But stopping metformin on your own can have serious consequences on your health. Here's what you need to know.

How Metformin Works

Glucose, aka blood sugar, is the body's main source of energy. The body gets glucose from two places: the carbohydrates in food, and the liver. Metformin works to reduce blood glucose levels from both of these sources, as described by a study published in the November 2013 issue of Pharmacogenet Genomics.

Once the body converts the carbohydrates in food into glucose, the hormone insulin moves the glucose out of the blood and into the cells, which use it for energy. But people with prediabetes and type 2 diabetes are resistant to insulin's effects, meaning that not enough glucose gets into their cells, according to the Mayo Clinic 16. This causes a buildup of glucose in the bloodstream, called hyperglycemia (high blood sugar). Metformin helps correct this by improving cells' ability to use insulin.

Read more: Normal Blood Sugar Range After Meals

Metformin lowers blood sugar levels throughout the day by limiting the amount of glucose released by the liver.

Metformin doesn't cure prediabetes or type 2 diabetes, but it does help reduce the symptoms and risks of chronic high blood sugar. That's why, if you have diabetes, stopping metformin can have adverse effects on your health.

The Effects of Stopping Metformin

Elizabeth Halprin, MD, clinical director of adult diabetes at the Joslin Diabetes Center in Boston, spoke with LIVESTRONG.com about the consequences of stopping metformin. "Metformin works very well in lowering blood glucose levels," she says. "If a person stops taking metformin, their blood glucose levels will go right up."

Stopping metformin won't cause the body to go into any kind of shock or metformin withdrawal, but Dr. Halprin says it will have an adverse impact on overall health. "The short- and long-term consequences are that blood sugars will go up," she notes. "[Type 2 diabetes] will not be treated unless you substitute metformin with another medication."

Short-Term Consequences

High blood sugar can cause immediate symptoms, which include the following, as listed by the ADA 46:

  • Frequent urination
  • Increased thirst
  • Blurred vision
  • Fatigue

Stopping metformin may also increase the risk of anxiety or depression. According to an analysis published in the February 2019 issue of Frontiers in Psychiatry, emerging research shows that metformin may help alleviate the symptoms of depression for people with type 2 diabetes.

Read more: What Are Normal Blood Sugar Levels and What Happens if They're High?

Long-Term Complications

According to the Mayo Clinic, chronic hyperglycemia can lead to 6:

Medical Reasons for Stopping Metformin

There are a number of reasons why a doctor might stop prescribing metformin to a patient. One of these is type 2 diabetes remission, wherein the patient's overall condition has improved to the point that diabetes medication is no longer needed, according to University of Wisconsin-Madison Health 9.

Dr. Halprin says that people may also need to stop taking metformin if they develop acute kidney disease. But she notes that today's clinicians understand the effects of metformin and kidney disease much better than they did in the past. "We have more definitive guidelines, so a person doesn't have to stop [metformin completely]," she says. "They can [just] decrease the dose."

What to Do if You Miss a Dose

According to the Mayo Clinic, the best thing to do if you accidentally miss a dose is to simply take the metformin as soon as possible 8. However, if you're close to the time when you normally take your metformin, you should wait and take it at your regular time. Do not double dose.

If you're concerned about missing one or more doses of metformin, contact your doctor, who can help you get back on track.