Do not take Metformin SR 500 Tablet if you are allergic to any of its components or if you have severe kidney disease, diabetic ketoacidosis, or metabolic acidosis. Inform the doctor if you have dehydration, infections, liver or kidney problems, uncontrolled diabetes, heart problems, or low levels of vitamin B12. Consult the doctor if you are pregnant or breastfeeding. Seek medical attention if you experience symptoms of lactic acidosis (vomiting, abdominal pain, muscle cramps, severe tiredness, difficulty breathing, and reduced body temperature and heartbeat) or dehydration (severe vomiting, diarrhoea, exposure to heat, fever or if you drink less fluid than normal).