feeling ill after b12 injection Why Do I Feel Worse My Injection? Vitamin B12 Side Effects

Peripheral neuropathy, subacute combined degeneration of the spinal cord, or cognitive impairment indicate more advanced deficiency and generally require intensive treatment over extended periods

In some cases, further tests may be required to identify the underlying cause, such as the Schilling test (now rare) or the detection of antibodies against intrinsic factor or gastric parietal cells

Whether used for medical necessity or off-label purposes, the potential complications range from uncomfortable to life-threatening, making it essential to approach treatment with appropriate medical supervision and preliminary testing

(PubMed) Simon JA, Hudes ES