The most important serious side effects include acute pancreatitis (severe persistent abdominal pain radiating to the back, though clinical trials found similar pancreatitis rates to comparators), severe dehydration from persistent vomiting or diarrhea (signs include dizziness, decreased urination, extreme thirst), gallbladder disease including cholecystitis or cholelithiasis (right upper quadrant pain, fever, jaundice), severe allergic reactions (difficulty breathing, swelling of face or throat), and severe hypoglycemia when combined with insulin or sulfonylureas (confusion, loss of consciousness, seizures)
Using sterile water without preservative would require discarding unused portions after each use, which is wasteful and impractical
Recommendations for practical use of Metformin, a central pharmacological therapy in type 2 diabetes
These are usually dose-dependent and most pronounced during titration