These extremely rare side effects include: Reactive thrombocytosis during the first week of use in megaloblastic anaemia Hypersensitivity reactions including: rash, itching, exanthema, antibodies to HYDR0XOCOBALAMIN-transcobalamin II Anaphylaxis Hypokalaemia Headache, paraesthesia, tremor Irregular heartbeat (arrhythmias secondary to hypokalaemia) Nausea Vomiting Diarrhoea Fever, chills, hot flushes, dizziness, malaise, pain and / or swelling at the injection site Acne Abnormal colouration of the urine (chromaturia) B12 injections work quickly
Some protocols emphasize local approaches near an injury site, while others emphasize systemic support
If weight loss is the goal and B12 levels are normal, plan evidence-based lifestyle changes and consider proven medical options as appropriate
Mild, temporary effects may include: Redness or soreness at the injection site Small bruise or swelling Nausea Mild headache A brief warm sensation after injection Serious reactions are extremely rare and most side effects resolve quickly
