metformin
Metformin is a first-choice medication to control your blood sugar and lower your risk of death from diabetes, although some people cannot tolerate the stomach side effects.
What is Metformin?
What is Metformin used for?
Type 2 diabetes
How Metformin works
Metformin is a medication used to manage diabetes. It lowers the amount of sugar your body makes or absorbs, and allows you to use your body's natural insulin better.
Drug Facts
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What are the side effects of Metformin?
Common Side Effects
- Diarrhea (53%)
- Nausea or vomiting (26%)
- Gas (12%)
- Indigestion (7%)
- Stomach pain (6%)
- Headache (6%)
Other Side Effects
- Weakness
- Headache
- Low vitamin B12 levels
- Change in taste
Serious Side Effects
- Lactic acidosis (too much lactic acid in the blood that can lead to death)
Source: DailyMed
More on Metformin side effects
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
Abdominal or stomach discomfort
cough or hoarseness
decreased appetite
fast or shallow breathing
fever or chills
general feeling of discomfort
lower back or side pain
muscle pain or cramping
painful or difficult urination
sleepiness
Less common
blurred vision
chest discomfort
cold sweats
coma
confusion
cool, pale skin
difficult or labored breathing
dizziness
fast, irregular, pounding, or racing heartbeat or pulse
feeling of warmth
headache
increased hunger
increased sweating
nervousness
nightmares
redness of the face, neck, arms, and occasionally, upper chest
seizures
shakiness
slurred speech
tightness in the chest
unusual tiredness or weakness
Rare
Behavior change similar to being drunk
difficulty with concentrating
drowsiness
lack or loss of strength
restless sleep
unusual sleepiness
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Acid or sour stomach
belching
bloated
excess air or gas in the stomach or intestines
full feeling
indigestion
loss of appetite
metallic taste in the mouth
passing of gas
stomachache
stomach upset or pain
vomiting
Less common
Abnormal stools
bad, unusual, or unpleasant (after) taste
change in taste
difficulty with moving
discoloration of the fingernails or toenails
flu-like symptoms
joint pain
rash
stuffy or runny nose
swollen joints
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Metformin
Pros
Very good at lowering blood sugar and A1c levels
One of the few diabetes medications that lowers the risk of death from diabetes-related complications
Doesn't cause weight gain
Rarely causes low blood sugar (hypoglycemia)
Available as a liquid (for those with trouble swallowing) and a long-acting tablet (to help with stomach side effects)
The short-acting tablet is cheaper than the long-acting tablet.
Cons
Can cause stomach side effects like diarrhea, nausea, gas, or stomach cramping
Usually not a good choice for people with more severe kidney problems
Excessive alcohol use can increase the risk of a dangerous side effect.
The liquid and long-acting tablet can be expensive even though they have generics.
Pharmacist tips for Metformin
Stomach side effects, especially diarrhea, are common with metformin. For most people, this will go away after a few weeks of taking it. If it doesn't stop or is excessive, ask your provider about the long-acting version of metformin, which is less likely to have these side effects.
Take your metformin with food to help lessen stomach upset.
Limit or avoid alcohol when taking this medication. Too much alcohol or chronic alcohol use can put you at risk for a life-threatening side effect called lactic acidosis.
Make sure to have any blood tests done and go to your regular check ups. This will tell your provider how well metformin is working for you.
Check your blood sugar regularly. Keeping a log of your sugar levels is helpful for your provider.
More on Metformin tips
Frequently asked questions about Metformin
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What are the risks and warnings for Metformin?
Metformin 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
Risk factors: Kidney problems | Liver problems | Heart problems | Age 65 or greater | Alcohol use | Using contrast dye
Metformin can, on rare occasions, cause a condition called lactic acidosis (too much lactic acid in your blood). This condition can lead to other health problems that can be deadly. Call your provider immediately if you experience fast breathing, fast or slow heartbeat, heartbeat that does not feel normal, very upset stomach or throwing up, feeling very sleepy, shortness of breath, feeling very tired or weak, dizziness, feeling cold, or muscle pain. These can be signs of too much lactic acid in your blood. Tell your provider about any existing health problems and other medications before taking metformin.
LOW VITAMIN B12 LEVELS
Risk factors: Long-term use of metformin | Lower than average calcium absorption | Lower than average vitamin B12 absorption
This risk is more relevant to people receiving long-term treatment with metformin. Metformin can cause low levels of vitamin B12, which can lead to anemia. Let your provider know about any persistent low energy, muscle weakness, low appetite, or tingling or numbness on hands or feet. A blood test can help determine if you have anemia and if metformin is the reason. Your provider should monitor your vitamin B12 levels at 2-3 year intervals.
LOW BLOOD SUGAR (HYPOGLYCEMIA)
Risk factors: Changes in diet and exercise | Drinking alcohol | Taking other medications for diabetes | Over age 65 | Liver or kidney problems
Metformin alone or together with other diabetic medications can cause low blood sugar. Very low blood sugar may be life-threatening. Symptoms of low blood sugar include feeling shaky, being nervous or anxious, fast heartbeat, sweating or body chills, confusion, feeling sleepy, weakness or low energy, and excessive hunger. Talk to your provider or pharmacist if you are concerned about this.
More on Metformin warnings
Metformin dosage forms
Typical dosing for Metformin
Metformin is usually started as 500 mg by mouth twice daily or 850 mg by mouth once daily. Depending on how well it works, the dose can be raised to a total of 2,550 mg by mouth per day split into a few doses throughout the day.
More on Metformin dosage forms
Interactions between Metformin and other drugs
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Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Acetrizoic Acid
- Diatrizoate
- Ethiodized Oil
- Iobenzamic Acid
- Iobitridol
- Iocarmic Acid
- Iocetamic Acid
- Iodamide
- Iodipamide
- Iodixanol
- Iodohippuric Acid
- Iodopyracet
- Iodoxamic Acid
- Ioglicic Acid
- Ioglycamic Acid
- Iohexol
- Iomeprol
- Iopamidol
- Iopanoic Acid
- Iopentol
- Iophendylate
- Iopromide
- Iopronic Acid
- Ioseric Acid
- Iosimide
- Iotasul
- Iothalamate
- Iotrolan
- Iotroxic Acid
- Ioxaglate
- Ioxitalamic Acid
- Ipodate
- Metrizamide
- Metrizoic Acid
- Tyropanoate Sodium
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aspirin
- Balofloxacin
- Besifloxacin
- Bupropion
- Capmatinib
- Chloroquine
- Ciprofloxacin
- Dasabuvir
- Dofetilide
- Dolutegravir
- Enoxacin
- Fleroxacin
- Flumequine
- Gatifloxacin
- Gemifloxacin
- Hydroxychloroquine
- Ioversol
- Lanreotide
- Levofloxacin
- Lomefloxacin
- Moxifloxacin
- Nadifloxacin
- Norfloxacin
- Octreotide
- Ofloxacin
- Ombitasvir
- Paritaprevir
- Pasireotide
- Pazufloxacin
- Pefloxacin
- Pioglitazone
- Prulifloxacin
- Ritonavir
- Rufloxacin
- Sitagliptin
- Sparfloxacin
- Tafenoquine
- Thioctic Acid
- Tosufloxacin
- Vandetanib
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Acebutolol
- Atenolol
- Betaxolol
- Bisoprolol
- Bitter Melon
- Carteolol
- Carvedilol
- Celiprolol
- Colesevelam
- Esmolol
- Fenugreek
- Furazolidone
- Glucomannan
- Guar Gum
- Iproniazid
- Isocarboxazid
- Labetalol
- Levobunolol
- Linezolid
- Methylene Blue
- Metipranolol
- Metoprolol
- Moclobemide
- Nadolol
- Nebivolol
- Nialamide
- Oxprenolol
- Patiromer
- Penbutolol
- Phenelzine
- Pindolol
- Practolol
- Procarbazine
- Propranolol
- Psyllium
- Ranolazine
- Rasagiline
- Rifampin
- Safinamide
- Selegiline
- Sotalol
- Timolol
- Tranylcypromine
- Verapamil
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