how to self inject b12 shots Best Vitamin Injection Sites: Where B12 · PA Relief Safe B12 Injection Guide at
Description
You need to take them consistently for at least 3 months to see visible results

Are they interchangeable

039 STAGE 1 Lv

why or why not

This could be due to racial differences in B12 metabolism, or in environmental factors, most obviously diet (B12 intake)
