Metformin Dosages for Adults and Children: Your GoodRx Guide

One of the most popular oral medications for Type 2 diabetes is metformin. Your healthcare provider may prescribe it to help manage your blood glucose (sugar). There are multiple metformin products available, including immediate-release (IR) and extended-release (ER) forms. But one isn’t considered better than another.

If you’re taking metformin, you may be curious about your dosage and any adjustments to expect. Here, we’ll cover typical metformin dosages, including any differences between products. Keep in mind your healthcare provider may have you take metformin differently.

What’s the typical metformin dosage for adults?

Metformin comes as both an IR tablet and oral solution. It’s also available as three different ER tablets. These include metformin ER, metformin ER OSM (Fortamet), and metformin ER MOD (Glumetza). The ER tablets are only approved for use in adults.

Metformin can cause several stomach-related side effects. Taking your dose with food can help lessen these effects, which should improve within a few weeks of starting treatment.

Keep in mind: Each ER tablet uses a distinct delivery mechanism allowing the medication to be slowly absorbed by your body. Because of this, they aren’t considered interchangeable with each other.

Type 2 diabetes

For adults, the starting metformin dosage for Type 2 diabetes is 500 mg once or twice daily, depending on the product you’re taking. The maximum dosage can also vary slightly by product.

Promotion disclosure

Metformin

Avg retail price

$8.24(Save 15.17%)

GoodRx discount

$6.99

Compare all prices

Metformin IR: The typical starting dosage for metformin IR is 500 mg twice daily, or 850 mg once daily, with food. If needed, your dose may be increased every 1 to 2 weeks to a maximum daily dose of 2,550 mg (taken as smaller, divided doses).

Metformin ER: The typical starting dosage for all forms of metformin ER is 500 mg once daily with your evening meal. If needed, your dose may be increased every 1 to 2 weeks to a maximum daily dose of 2,000 mg.

It’s possible to switch from metformin IR to metformin ER. This may help reduce the number of pills you’re taking and potentially lessen side effects. Talk to your healthcare provider if you’re interested in making the switch.

What’s the typical metformin dosage for children?

Metformin is the only oral medication approved to treat Type 2 diabetes in children. This includes children and adolescents ages 10 and older. But only the IR tablets and oral solution are approved for this age group. That’s because metformin ER hasn’t been studied in children.

Type 2 diabetes

The typical metformin dosage for children starts at 500 mg twice daily with meals. If needed, their healthcare provider may slowly raise the dose every 1 to 2 weeks. The maximum daily dose is 2,000 mg (taken as 1,000 mg twice daily).

Are there any dosage adjustments for medical conditions?

If you have kidney problems, your healthcare provider may decide to lower your metformin dosage. This is because your kidneys clear metformin out of your body. If they don’t clear metformin properly, there’s an increased risk of side effects. One of these is lactic acidosis, a rare but dangerous condition caused by too much lactic acid in your blood.

In this case, your healthcare provider will monitor your estimated glomerular filtration rate (eGFR). This is a blood test performed by your healthcare provider to assess your kidney function. Your GFR can determine your metformin dosage. And if your eGFR is too low, metformin may not be safe for you to take.

Similarly, liver problems can also increase the risk of lactic acidosis. If you have liver problems, metformin may not be recommended.

What happens if you miss a dose of metformin?

If you forget to take your metformin dose, take the dose you missed as soon as you remember. But if it’s almost time for your next dose, just skip the one you missed and get back on schedule. You shouldn’t take two doses to make up for the one you missed.

What should you do if you take too much metformin?

If you accidentally take too much metformin, you may experience side effects like diarrhea, nausea, or stomach pain. Hypoglycemia (low blood glucose) isn’t as common with metformin on its own. But if you feel weak, shaky, or sweaty, be sure to check your blood glucose. If it’s less than 70 mg/dL, follow the instructions you’ve been given for bringing it back up to normal.

Certain people may be at higher risk of lactic acidosis if they take too much metformin. Examples include people with kidney problems or liver problems, and older adults. Get immediate medical attention if you develop trouble breathing, muscle aches, and stomach pain.

If you think you’ve taken too much metformin, you can reach Poison Control at 1-800-222-1222. If any symptoms you’re experiencing feel life-threatening or severe, go to your nearest emergency room.

How to save on metformin

There are many ways to save on metformin, which is available as both a brand-name and generic medication. GoodRx can help make your metformin prescription more affordable.

Generic metformin IR’s price at certain pharmacies is as low as $6.99 with a free GoodRx discount. Generic metformin ER is as low as $17.04, generic Glumetza is as low as $56.70, and generic Fortamet is as low as $29.98.

Why trust our experts?

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:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Our editorial standards

Meet our experts