How Long Does It Take for Metformin to Work? Plus, Answers to 6 More Metformin FAQs
Metformin is an oral medication that is FDA approved to treat Type 2 diabetes. Learn how long it takes for metformin to work and explore tips on how to take it.
metformin ER
Used for Diabetes Type 2, Gestational Diabetes
Used for Diabetes Type 2, Gestational Diabetes
Metformin extended-release (ER) is a type of diabetes medication. It treats Type 2 diabetes in adults when used along with a balanced diet and regular exercise. The medication works as a biguanide to help lower blood sugar. The usual dosage for metformin ER is taken by mouth once daily with your evening meal. This helps minimize some side effects, such as diarrhea and nausea. The brand name Glucophage XR is no longer available, but generic versions of metformin ER are still on the market.
What is Metformin ER?
What is Metformin ER used for?
- Type 2 diabetes in adults
How Metformin ER works
Metformin ER is a biguanide that works in a few ways to lower your blood sugar.
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It lowers the amount of sugar your liver makes.
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It also lowers the amount of sugar that's absorbed through your gut from food you eat.
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It also helps your body respond better to insulin. This helps your cells take up sugar from the blood and use it as energy better.
When does Metformin ER start working?Time passed since treatment started:
Drug facts
| Common Brands | Glucophage XR |
|---|---|
| Drug Class | Biguanide |
| Controlled Substance Classification | Not a controlled medication |
| Generic Status | Lower-cost generic available |
| Availability | Prescription only |
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Side effects of Metformin ER
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
- Diarrhea (10%)
- Nausea or vomiting (7%)
Less Common Side Effects
- Belly pain
- Constipation
- Swollen belly
- Indigestion or heartburn
- Excess gas
- Dizziness
- Headache
- Upper respiratory infection
- Changes in taste
Metformin ER serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Lactic acidosis (buildup of lactic acid): feeling unwell, feeling tired or weak, unusual muscle pain, fast breathing, sleepiness, confusion, feeling cold, fast heart rate
When do Metformin ER possible side effects begin and end?
Time passed since treatment started:
H
D
W
M
Diarrhea
Nausea or vomiting
Stomach pain
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The following Metformin ER side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- High lactic acid level—muscle pain or cramps, stomach pain, trouble breathing, general discomfort and fatigue
- Low vitamin B12 level—pain, tingling, or numbness in the hands or feet, muscle weakness, dizziness, confusion, trouble concentrating
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
Pros and cons of Metformin ER
Pros
- Taken once a day
- Might cause less diarrhea than metformin immediate-release
- Might cause modest weight loss
Cons
- Must be taken with the evening meal
- Can cause stomach problems, like nausea
- Not recommended for people with moderate-to-severe kidney problems
Pharmacist tips for Metformin ER
- Take metformin ER with your evening meal. Taking it with food can help lower the chance of stomach side effects, like diarrhea, nausea, and belly pain.
- Swallow metformin ER tablets whole. Don't cut, crush, or chew them. This can affect how the medication is released into your body.
- You might see what looks like a tablet in your stool. This is normal. Your body has already absorbed metformin ER, and what you see is the empty tablet shell.
- Take metformin ER every day as prescribed. It can take up to 2 months to get the full benefit of the medication.
- Drink enough fluids to stay hydrated while taking metformin ER. This is especially important if you have side effects like vomiting or diarrhea or if you get sick. Dehydration can raise your risk of a rare but serious condition called lactic acidosis.
- Get any blood tests done when your prescriber recommends them. Sometimes, your prescriber will need to check your kidney function. Your kidneys help remove metformin ER from your body. If your kidneys aren't working well, the medication can build up and raise your risk of lactic acidosis.
- It's best to avoid or limit alcohol when possible while taking metformin ER. Alcohol can make side effects like stomach upset worse. It can also affect how well your blood sugar can be controlled. Heavy drinking or drinking often can raise your risk of lactic acidosis, which can be dangerous. Talk to your prescriber before drinking alcohol while taking metformin ER.
- Tell your prescriber if you're having surgery or an imaging test that uses contrast dye. You might need to stop metformin ER for a short time. Your prescriber will tell you when to stop it and when it's safe to start taking it again. This can help lower your risk of lactic acidosis.
- Get medical help right away if you have symptoms of lactic acidosis. These can include severe weakness, trouble breathing, dizziness, or unusual muscle pain. Lactic acidosis is a rare but serious side effect of metformin ER.
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Risks and warnings for Metformin ER
Metformin ER can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Lactic acidosis (too much acid in your body)
- Risk factors: Age 65 or older | Kidney or liver problems | Heart failure or heart attack | Not eating food or fasting before surgery | Imaging procedure using contrast dye | Mitochondrial disorders | Heavy drinking | Taking medications that affect the kidneys or the blood's acid-base balance | Taking medications that raise metformin levels
In rare cases, metformin ER can cause a serious medical condition called lactic acidosis. This happens when too much lactic acid builds up in your blood. If left untreated or if severe, it can lead to other health problems, like low blood pressure, fast heart rate, or serious organ failure. This can be life-threatening. Talk to your prescriber about your medical history and planned procedures so they can check your risk.
Watch for early signs of lactic acidosis. These include feeling unwell, feeling tired or weak, muscle pain, fast breathing, sleepiness, or confusion. Get emergency medical help if you suddenly have these symptoms.
Low vitamin B12 levels
- Risk factors: Long-term use of metformin | Low vitamin B12 intake or absorption | Low calcium intake or absorption
Metformin ER can sometimes lower your vitamin B12 levels. Low vitamin B12 levels can lead to anemia.
Your prescriber might check your blood count every year while you're taking metformin ER. They also might check your vitamin B12 levels every 2 to 3 years. If your vitamin B12 is low, they might recommend a vitamin B12 supplement or make changes to your medication. This can help your vitamin B12 levels return to normal.
Tell your prescriber if you feel unusually tired or weak, have pale skin, or notice numbness or tingling in your hands or feet. These can be signs of low vitamin B12.
Risk of low blood sugar when taken with certain other diabetes medications
Taking metformin ER with insulin or sulfonylureas, like glipizide, can put you at risk of low blood sugar. Very low blood sugar can be dangerous and even life-threatening.
Be sure you can recognize symptoms of low blood sugar. This can include feeling shaky, anxious, confused, sleepy, weak, or very hungry. You might also have a fast heartbeat, be sweaty, or have chills.
If you have these symptoms, check your blood sugar and treat any low blood sugar right away. Talk to your prescriber or pharmacist about your risk for low blood sugar.
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Metformin ER dosage
The average cost for 90 tablets of 500mg of Metformin ER is $14.90 with a free GoodRx coupon. This is 60.28% off the average retail price of $37.51. 
Tablet
Tablet| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 750mg | 180 tablets | $25.48 | $0.14 |
| 500mg | 90 tablets | $14.90 | $0.17 |
Typical dosage for Metformin ER
The typical starting dose is 500 mg by mouth once daily with the evening meal. If needed, your prescriber might raise your dose every week to get to the dose that works best for you. The maximum dose is 2,000 mg once daily.
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How much does Metformin ER cost?
To access savings, use a GoodRx coupon and pay just a fraction of the retail price.
Metformin ER (generic)
$14.90
Metformin ER contraindications
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Metformin ER will not be safe for you to take.
- Severe kidney problems
- High acid levels in the blood (metabolic acidosis), including diabetic ketoacidosis
What are alternatives to Metformin ER?
There are a number of medications that your doctor can prescribe in place of Metformin ER. Compare a few possible alternatives below.
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Metformin ER images
