Anemia, a condition in which the blood does not contain enough red blood cells, is frequently brought on by renal failure and hemodialysis
B12 occurs naturally in meats, dairy, fish, and other animal products

B12 has many functions in our body, so unfortunately a deficiency will give rise to a wide variety of symptoms, like brain fog, memory problems, cognitive impairment, insomnia, headaches, especially migraine, behavioural changes, learning problems, nominal aphasia, mood swings, irritability, depression, anxiety, hallucinations, delusions, psychosis, peripheral paraesthesia (pins and needles), numbness, neuropathic pains, poor balance, reduced vibration sense or proprioception (joint position sense), tinnitus, ataxia, taste impairment, sometimes myelopathy, fatigue, anaemia (either with larger red blood cells, or with normal size of the red blood cells when there is also iron deficiency), other reduction in blood cells, abdominal complaints, malabsorption, failure to thrive, weight loss, diarrhoea, hyperpigmentation, glossitis, (aphthous) stomatitis, infertility, urinary tract infections, joint and muscle pain, muscle weakness, spasticity, seizures, cardiomyopathy, urinary and/or faecal incontinence, postural hypotension/dizziness, erectile dysfunction, to name a few

If the half life is 6 days, why do I get symptoms outside the 48hr mark
Reconstitution math, syringe volumes, and injection technique are not academic details: get any of them wrong and the result ranges from an ineffective product to a genuine safety risk
Drawing B12 into a transparent syringe and injecting it within minutes isnt a problem, but storing it long-term in a transparent container isnt smart