Three very common options when applying some treatments, some that produce their effect faster than others and everything will depend on what the doctor indicates, although as my friend says, the intravenous way is one of the fastest in achieving an effect and they go directly. into the person's bloodstream.

Two methods that are the most seen and used are intravenous and intramuscular, vitamin B12 is obtained both in pills and in injection, the latter being effective but bringing benefits, it goes directly to the bloodstream and stimulates red blood cells.

Saludos 🇻🇪👍