What is metformin used for?
• Prediabetes, Type 2 Diabetes
How does it work?
• Metformin helps keep blood sugars in a normal range by helping our body use our own insulin better. It also causes the liver to make less sugar.
What forms does metformin come in?
• Metformin immediate release
o 500 mg tablets, 850 mg tablets, 1000 mg tablets, Liquid suspension 500mg/5mL
• Metformin extended release (ER)
o 500 mg tablet, 750 tablet, 1000 mg tablet
How will my metformin be dosed?
• Usually, patients start at a lower dose of metformin and then increase to a goal dose. This can help decrease side-effects. Discuss titration with your provider.
• Immediate release metformin is dosed twice a day and extended release (ER) is dosed once a day
Can I crush metformin?
• You can crush immediate release metformin but not extended release
What if I miss a dose?
• If it has been less than 2 hours since the missed dose take the dose otherwise skip that dose.
• DO NOT take missed dose and usual dose doses at the same time.
What are common side effects?
• Loose stools, upset stomach, gas
• Less common- Vitamin B12 deficiency (can be associated with anemia)
• Some patients say that metformin has a “fishy” smell but that is normal, and it is not an indication that there is something wrong with the medication
What can help make my side effects better?
• Less side effects with the extended release (ER) form
• Taking with food
• Taking before bed
• Smaller dose (talk with your prescriber before changing the prescribed dose)
• Time! Usually symptoms decrease over a few weeks of continued use
Who should not use metformin?
• Those whose kidneys do not work well
• Those with too much acid in the blood (metabolic acidosis or DKA)
What are serious side effects of metformin?
• Lactic acidosis (a form of too much acid in the blood)
• Low blood sugars (when combined with other drugs that lower blood sugar such as insulin)
• Severe allergic reaction
When should I not take my metformin?
• If you are vomiting and/or are dehydrated
• If you are scheduled for a medical or dental procedure or imaging study (such as a CT scan or an MRI)- do not take metformin for 48 hours before and 24 hours after
When should I call my doctor?
• Side effects of nausea/diarrhea/gas/upset stomach that do not go away in 2 weeks
• Severe allergic reaction (e.g. rash, hives, wheezing, tight chest, swelling in face)
• If you have symptoms of too much lactic acid (e.g. weakness, severe stomach pain, sleepiness, fasting and shallow breathing, muscle cramping)
References:
Merck. Glucophage (Metformin hydrochloride). U.S. Food and Drug administration website. www.accessdata.fda.gov/drugsatfda_docs/label/2017/020357s037s039,021202s021s023lbl.pdf. Revised April 2017. Accessed April 27, 2022.
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