But like any treatment, it comes with its own set of benefits and risks
However, when very high oral doses are taken, approximately 1% can be absorbed through passive diffusion, independent of intrinsic factor, which explains how mega-doses can still raise serum levels
However, there are important considerations when using both treatments concurrently
For vitamin B deficiency (e.g., pernicious anemia), a common regimen is to begin with frequent intramuscular injections to replenish body stores
Common symptoms can include: Extreme fatigue Lethargy Loss of appetite headaches Feeling faint or dizzy Breathlessness Headaches Heart palpitations Tinnitus Additional symptoms of B12 deficiency can include psychological problems such as low mood, irritability, depression, cognitive changes, or blurred memory