Individuals at risk of vitamin B12 deficiency include older adults, people with gastrointestinal disorders, those who have had gastrointestinal surgeries, individuals on a strict vegan diet, individuals who take metformin for blood sugar control, and people taking proton pump inhibitors for chronic heartburn
It's simple to inject B12
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
It depends on whether you are actually low