Metformin Side Effects

The most common side effects of metformin include:

• Diarrhea
• Stomachache
• Bloating
• Gas
• Indigestion
• Heartburn
• Constipation
• Headache
• Metallic taste in the mouth
• Skin flushing
• Nail changes
• Muscle aches

Please tell your doctor if these metformin side effects are severe, do not go away, go away but come back again, or develop some time after you start taking the medication. 

Some of the side effects of metformin are more serious. You should contact your doctor without delay or get emergency treatment for the following side effects:

• Chest pain
• Rash
• Difficulty breathing
• Irregular heart rate
• Dizziness

The above list may not include all the potential side effects of metformin. Talk to your doctor if you have severe side effects or if the side effects do not improve over time. You can also report unusual Metformin side effects to the Food and Drug Administration at 1-800-FDA-1088.

Can metformin cause nausea and diarrhea?

Gastrointestinal side effects are common in patients taking metformin. Up to 75% of those who are taking metformin experience diarrhea, nausea, vomiting, and/or abdominal pain. Taking metformin with food or snacks can help ease these tummy side effects, and the good news is that these bothersome side effects tend to get better after a few weeks once your body gets used to this medication.  

Does metformin cause constipation?

Rarely, metformin can cause constipation. To help avoid constipation during metformin treatment, drink enough water, get enough exercise, and eat fiber-rich foods. Notably, one of the signs of low B12 levels is constipation. Let your doctor know if constipation persists. A B12 supplement may be helpful in many cases. 

What are the long-term side effects of metformin?

Long-term side effects of metformin can include vitamin B12 deficiency. Signs of a vitamin B12 deficiency include tiredness, dizziness, difficulty breathing, and feeling faint. Low B12 levels can also cause some digestive problems, such as nausea, bloating, constipation or diarrhea. 

What are the side effects of 1,000 mg of metformin?

Both metformin formulations, immediate-release (IR) and extended-release (ER), are available in 500-milligrams (mg) and 1000-mg strengths, and these two strengths can cause the same side effects. The side effects of metformin 1000mg would include gastrointestinal (GI) side effects such as nausea, vomiting, diarrhea, and gas, especially at the beginning of therapy when your body is still getting used to the effects of this medication. However, the concept of higher doses leading to more significant side effects is also relevant here. Therefore, to alleviate the side effects of metformin 1000mg, metformin is typically started at 500 mg by mouth twice a day or 850 mg by mouth once daily. Taking metformin with food or snacks can also help reduce some of the tummy problems. These GI side effects from metformin are very common, and it is expected to improve after a few weeks. Let your doctor know if these GI symptoms persist. Dosage adjustment or switching to the extended-release (ER) formation can help in many cases.  

Can metformin make you tired? 

Long-term use of metformin can potentially cause vitamin B12 deficiency, which can cause you to feel more tired.

Can metformin reduce your appetite?

Taking metformin can indirectly reduce your appetite. Metformin is known to cause tummy upset, including symptoms like diarrhea, bloating, and nausea, which, in turn, can cause loss of appetite. 

Can metformin cause sweating?

Metformin causes changes in your blood sugar levels. Increased sweating is one of the early signs of hypoglycemia (low blood sugar), in addition to hunger, feeling anxious, and shakiness. You should be aware of the signs and symptoms of high and low blood sugar and know what to do if you develop these symptoms.

Metformin Overdose: Under certain conditions, an overdose of metformin can cause a serious, potentially life-threatening condition called lactic acidosis. Symptoms of metformin overdose can include symptoms of hypoglycemia (low blood glucose levels), weakness, extreme tiredness, nausea, vomiting, stomach pain, decreased appetite, shortness of breath, rapid and deep breathing, lightheadedness, dizziness, abnormally slow or fast heartbeat, feeling cold, flushing of the skin, and muscle pain. If you experience any of these symptoms, stop taking metformin and call your doctor immediately. NOTE: Metformin is a prescription medicine to be used only by you - never share your medication with others or use someone else’s metformin.

Source: FDA