What are the side effects of metformin?

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Metformin Side Effects

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Simple Answer

Metformin can cause stomach and gut side effects. In the source material, the most common ones listed are diarrhea, and it says gradual dose increases are used to help reduce gastrointestinal side effects. The source also lists rare but serious problems like lactic acidosis and vitamin B12 deficiency. It also mentions low blood sugar can happen when metformin is used with insulin or certain other diabetes medicines.

What It Means

This matters because some side effects are common and mild, while others are serious and need fast medical care. Knowing the warning signs can help you get help early if something does not feel right.

When to Contact a Doctor

Talk to your doctor if you have bothersome diarrhea or other stomach side effects, or if you think you are having side effects that are not going away. Also contact your doctor if you are taking metformin with insulin or an insulin secretagogue and are worried about low blood sugar.

Get Urgent Help If…

Get urgent medical help if lactic acidosis is suspected. The source says symptoms can include malaise, muscle aches, trouble breathing, sleepiness, and abdominal pain. It also says serious allergic reactions like anaphylaxis or angioedema are reported, and these need urgent care.

Side effect rates can vary by study and by person. The source notes that gradual dose escalation may help reduce metformin-related stomach side effects.

Sources

This information is based on these free U.S. government medical sources:

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This service provides general medical information and education. It does not diagnose medical conditions or replace care from a physician or other qualified healthcare professional. If you may be experiencing a medical emergency, call 911.