Metformin is a commonly prescribed medicine for type 2 diabetes and is also used for some other conditions. Like any medication, it can cause side effects. Many are mild and improve as the body adjusts, but some symptoms should be discussed with a healthcare professional.
Here are 10 side effects you may experience while taking metformin.
1. Nausea
Feeling sick is one of the more common side effects, particularly when starting metformin or increasing the dose.
2. Diarrhea
Loose stools can occur, especially during the first few weeks. Taking metformin with food may help reduce stomach-related symptoms.
3. Stomach Discomfort
Some people experience abdominal discomfort, cramping, or a feeling of fullness after taking the medicine.
4. Gas
Increased gas or bloating can occur because metformin affects how the digestive system handles glucose.
5. Loss of Appetite
Some people notice that they feel less hungry while taking metformin. If you experience significant or persistent loss of appetite, tell your healthcare professional.
6. Changes in Taste
A metallic or unusual taste in the mouth can occur in some people taking metformin.
7. Indigestion
Heartburn or general digestive discomfort may occur, particularly when beginning treatment.
8. Headache
Headaches can occur while taking metformin, although they can also have many other causes.
9. Vitamin B12 Deficiency
Long-term metformin use can reduce vitamin B12 levels in some people. Your healthcare professional may recommend monitoring B12, particularly if you develop symptoms such as unusual tiredness, weakness, numbness, or tingling.
10. Low Blood Sugar—Usually With Certain Other Medicines
Metformin by itself generally does not cause low blood sugar. However, the risk can increase when it is combined with insulin or certain other diabetes medicines.
When Should You Seek Medical Help?
A rare but serious complication called lactic acidosis can occur, particularly in people with significant kidney problems or certain other risk factors.
Seek urgent medical attention if you develop severe weakness, unusual sleepiness, difficulty breathing, persistent vomiting, severe abdominal discomfort, or feeling unusually cold.
Should You Stop Metformin If You Have Side Effects?
Don’t stop or change your dose on your own. If side effects are troublesome, contact your doctor. They may adjust the dose, recommend taking it differently, or consider an extended-release formulation when appropriate.
The Bottom Line
Metformin is generally well tolerated, but digestive side effects are common, especially when treatment begins. Most are manageable, while long-term vitamin B12 deficiency and rare serious reactions deserve medical attention.
Important: This article is for general information and does not replace advice from your doctor or pharmacist.