Feeling worse after B12 Injection: Answering concerns. La Vie Med Spa Now offering B12 injections! If these symptoms sound all too familiar, it might be time to check your vitamin levels. B12 injections may be absorbed up to 90% more effectively than oral How Quickly Do You Feel Better After B12 Injections? Mean Plasma Concentration time profile of total vitamin B12 after Download Scientific Diagram How soon do you feel less tired after a B12 injection? Vital Force IV Therapy