The guidelines are for people at high risk to be screened with a routine blood test at least once a year
Limitations of Evidence Limitations of Evidence Animal-dominant data: Most findings are from rodent and cell models

Neurological: convulsions, increased intracranial pressure with papilledema (pseudotumor cerebri) usually after treatment, vertigo, headache Endocrine: menstrual irregularities, development of cushingoid state, suppression of fetal intrauterine or childhood growth, lack of secondary response of the adrenal cortex or pituitary gland, particularly in situations of stress such as trauma, surgery or illness, decreased carbohydrate tolerance, manifestations of latent diabetes mellitus, increased requirements of insulin or oral hypoglycemic agents in diabetic patients Ophtalmic: posterior subcapsular cataracts, increased intraocular pressure, glaucoma, exophthalmos Metabolic: negative nitrogen balance due to protein catabolism Psychiatric: euphoria, mood swings, severe depression to frank psychotic manifestations, personality changes, hyperirritability, insomnia Others: anaphylactoid or hypertensive reactions and hypotension or shock-like reaction Cyanocobalamin and hydroxocobalamin: hypervitaminosis and side effects were not observed with their use Dosage and administration Adults Coated tablets: 1 coated tablet 2 times a day

Initial treatment may involve frequent injections followed by maintenance regimens, with periodic review of symptoms and, where appropriate, blood counts
Vitamin B12 injections are generally safe, but some people may experience side effects, such as pain, redness, or swelling at the injection site, mild headaches, dizziness, nausea, or itching
But, serious side effects are rare