What Happens When You Stop Taking Metformin?

Metformin is often a first-choice medication approved to treat Type 2 diabetes. It is often a good option for adults and for children ages 10 and older. Once you start taking metformin, you’ll typically continue taking it long term — with a few exceptions.

For most people, metformin is safe and has mild side effects that improve after the first weeks of treatment. For others, however, metformin can be difficult to tolerate, or it might not be the best choice because of other health conditions. So what happens when you stop taking metformin?

What is metformin?

Metformin is an oral medication for Type 2 diabetes that’s been around for decades. It’s approved for adults and for children ages 10 and older. You may be prescribed metformin on its own or in combination with other diabetes medications.

Metformin comes in a few forms, including an oral solution, immediate-release tablets, and extended-release tablets (Fortamet, Glumetza). For convenience, metformin is also available in combination with other medications that lower blood glucose, in drugs such as Janumet and Synjardy. 

Metformin can lower hemoglobin A1C (your average blood glucose levels over 3 months) by an average of about 1%. It does this in a few ways. Metformin slows down the amount of glucose made by your liver and helps your body become more sensitive to the insulin it produces. It also lowers the amount of glucose you absorb from food. 

Why do some people stop taking metformin?

Most people who are prescribed metformin take it for multiple years. It’s known to be safe when taken long term and has many benefits beyond helping to manage Type 2 diabetes. But there are a few reasons why your provider may have you stop taking metformin:

1. You aren’t able to tolerate the side effects. Metformin is known for causing side effects like diarrhea, nausea, vomiting, and gas. These side effects are more likely when you first start taking the medication. Most of the time, they resolve within a few weeks. But some people find metformin’s side effects difficult to tolerate.

2. Your kidney function is too low. Some people may need to stop taking metformin if they have kidney problems. Metformin doesn’t directly harm the kidneys. But it can build up in your body if your kidneys aren’t working well. Depending on your level of kidney function, your provider may decide that metformin isn’t right for you anymore.

3. You don’t need metformin anymore. Type 2 diabetes isn’t considered a health condition that can be cured. But certain people who make long-term lifestyle changes may be able to reduce their need for metformin enough that their healthcare provider recommends stopping the medication. These lifestyle changes usually include a diabetes-friendly diet, weight loss, and exercise. Genetics also play a role in diabetes progression and insulin resistance.

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What happens when you stop taking metformin?

As covered above, metformin works a few different ways to control blood glucose levels. But metformin has these effects only while you’re taking it. 

If you stop metformin, its blood glucose benefits won’t be sustained — unless other treatments or lifestyle changes take its place. Your blood glucose may rise, or even return to the level it was at before you began taking metformin. This depends on your diet and other factors. 

When your blood glucose level is higher than your target range, it is called hyperglycemia. Symptoms of hyperglycemia can include feeling thirsty, needing to urinate frequently, and feeling weak or tired. Over time, more serious complications, such as heart disease, nerve damage, and vision changes, can also develop. 

Is it risky to stop taking metformin on your own?

Yes, it can be. If you stop metformin without discussing it with your provider first, your diabetes may become uncontrolled. This can increase the risk of complications and make your blood glucose harder to control down the road.

When should you talk to your healthcare provider about stopping metformin?

If you’re thinking about stopping metformin, talk to your healthcare provider before you do. If you’re wanting to stop the medication because of its side effects, there are other options they may have you try first. For example, some people find that extended-release versions of metformin are easier to tolerate.

And if you want to try a medication-free approach to managing your diabetes, you should have a discussion with your provider before making any changes. Together, you can come up with a plan that’s appropriate for your situation. For example, they may slowly lower your metformin dose to see how your blood glucose levels respond.

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Written by:

Julie Adkison, PharmD, BCACP, CDCES

Julie Adkison, PharmD, BCACP, CDCES, is a clinical pharmacist specializing in ambulatory care practice and diabetes care and education. She has worked in a faculty position in family medicine for many years.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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