Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
This medication may cause lactic acidosis (a build-up of lactic acid in the body, which can be fatal). Lactic acidosis can start slowly and get worse over time. Get emergency medical help if you have even mild symptoms of lactic acidosis, such as:
- muscle pain or weakness;
- numb or cold feeling in your arms and legs;
- trouble breathing;
- feeling dizzy, light-headed, tired, or very weak;
- stomach pain, nausea with vomiting; or
- fast or uneven heart rate.
Call your doctor at once if you have any other serious side effect such as:
- urinating less than usual or not at all; or
- nausea, pain in your upper stomach, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).
- Less serious side effects may include:
- mild nausea, vomiting, diarrhea, gas, or stomach pain;
- mild skin rash or itching;
- weakness; or
This is not a complete list of side effects and others may occur.