Vitamin B12 Shots Confer No Benefit vs. a Supplement Gene Food Experiencing a Metallic Taste After Getting an Injection Understanding Metallic Taste in Mouth: Causes and Solutions Metformin is a commonly used drug for managing Type 2 Diabetes. It's generally safe, but like all medications, it can cause side effects. Common side effects (most frequent) These often improve after Vitamin B12 deficiency symptoms that show up in your mouth The Mirror