Intravenous is the most effective and fastest way for quick relief from pain, as it delivers medicine directly into the bloodstream.

As far as I know, choosing intravenous administration for quick relief makes sense because it allows the medicine to act swiftly by entering the bloodstream directly, eliminating the need for additional absorption processes, which may delay the pain relief.

Vitamin B12 is often indicated more in injections due to absorption problems, efficacy, and specific medical conditions.

From my observation, the preference for injecting Vitamin B12 is logical, considering absorption issues in the digestive tract. This method ensures direct entry into the bloodstream, enhancing efficacy, especially for individuals with specific medical conditions requiring a rapid boost in vitamin levels. Moreover, patient preferences and condition has also some role to play.

Good luck .