The reason is that injections are more easily absorbed by the body, particularly if you have underlying conditions that may lead to an inability to efficiently absorb the vitamin, such as Irritable Bowel Syndrome or Celiac Disease
Vitamin B12 injections usually dont cause side effects for most people
All vitamin B complex supplements tend to interfere with antibiotics' effectiveness, and therefore they should be taken at different times
Heat above 25C can also potentially be a problem, although less so
These mistakes can hinder the absorption and utilization of vitamin B12, potentially reducing the effectiveness of the treatment
If you have absorption problems whether from digestive conditions, medications, or pernicious anemia oral supplements won't work effectively no matter how high the dose