Serious reactions are rare, but an allergic reaction is possible with any injection, which is another reason a first dose in trained hands is sensible

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

Nakajima, M
Both stimulants and GLP-1s can dry you out
Better brain function Mental clarity and efficient cognitive function partially rely on the presence of plenty of vitamin B12 in your system