Side Effects of Metformin
Metformin is one of the most widely prescribed medications to lower blood sugar and increase insulin sensitivity. This is because it’s inexpensive and it works well. It also has a good safety profile. On the other hand, all medications have side effects, and metformin is no exception. What are the side effects of taking metformin?
Common Side Effects of Metformin
The most common side effects of metformin are related to the digestive tract. Up to one in three people who take this medication experience symptoms such as nausea, abdominal bloating, vomiting, decreased appetite or diarrhea. According to one study, these side effects may be less pronounced in people who take an extended-release form of metformin or when the dosage of metformin is reduced. Taking the medication with food may also reduce the diarrhea and stomach upset associated with taking metformin. These symptoms are one of the most common reasons people stop taking the drug.
Less commonly, a person taking metformin can develop an allergic response to some ingredient in the medication. Symptoms of an allergic reaction to metformin include skin rash or itching. If more severe, symptoms such as difficulty breathing, chest pain, difficulty swallowing, swelling in the throat or lightheadedness may develop. A serious allergic reaction to metformin is rare, but it can be a medical emergency.
A Rare, but Serious Side Effect of Taking Metformin
The most serious side effect of taking metformin is the risk of developing a condition called lactic acidosis. Fortunately, this happens in only about 1 out of 16,000 people who take the medication, but it can be life-threatening. Lactic acidosis is a condition where lactate builds up in the blood stream. It occurs most commonly in people who have reduced liver or kidney function, lung disease or some types of heart disease that makes it more difficult to clear lactate from the bloodstream. This is why people who have these conditions shouldn’t take metformin. It’s also linked with drinking excessive amounts of alcohol while on the drug.
Symptoms of lactic acidosis include lightheadedness, rapid breathing, a sudden drop in blood pressure, vomiting, abdominal pain, confusion, extreme weakness, lightheadedness or fainting. These symptoms require emergency care and hospitalization.
If you undergo a study that involves the use of contrast dye, it’s important to stop metformin and not restart it until 48 hours after the procedure. Contrast dye can affect kidney function, which can increase the risk of lactic acidosis.
People Who Take Metformin Long-Term Can Develop Vitamin B12 Deficiency
Vitamin B12 is important for healthy red blood cells and normal nerve function. Over time, metformin can lower vitamin B12 levels, which can increase the risk of serious B12 deficiency symptoms. That’s why it’s a good idea to monitor vitamin B12 levels while taking this medication.
The Bottom Line?
The most common side effects of metformin are digestive complaints, which seem to be dose-related. This means they may become less pronounced if the dose is lowered and with an extended-release form of metformin. Talk to your doctor if you’re having problems tolerating it.