Common experiences after the first injection include: Mild soreness or redness at the injection site (usually resolves within 12 days) Slight improvement in energy levels or mood No immediate noticeable change (particularly common if deficiency is severe) Rarely, mild side effects such as headache or dizziness Some patients report their urine becoming brighter or more intensely coloured following injection, which occurs because excess B12 is excreted renally
Symptoms associated with vitamin B12 deficiency include fatigue and lack of energy (due to anemia), and depression, psychosis and even dementia
Rights and permissions About this article Cite this article Ghaben, A.L., Scherer, P.E
The available human safety data is limited
It is a material difference in what the patient is actually injecting
Seek medical attention promptly if you experience symptoms that could suggest serious underlying conditions, including: Unexplained weight loss or persistent fatigue Jaundice (yellowing of skin or eyes), abdominal pain, or swelling Easy bruising or bleeding , or unusual skin rashes Night sweats , fever, or enlarged lymph nodes Reduced urine output , significant swelling in legs or ankles Persistent itching without obvious skin cause These symptoms may indicate liver disease, haematological disorders, or renal impairmentconditions that can elevate B12 and require specialist assessment