arm sore after b12 injection How to self-inject intramuscular vitamin - Overview Why does my arm hurt

Never attempt to use questionable medication, as degraded compounds may lose potency or pose safety risks

You have some wiggle room, but if you fall off your schedule for too long, those signs of fatigue will inevitably return, and they almost always arrive on the scene before any other symptom does

Common adverse effects include: Injection site reactions pain, redness, swelling, or bruising at the intramuscular injection site Gastrointestinal disturbances nausea, diarrhoea, or abdominal discomfort Headache and dizziness particularly following initial doses Skin reactions including rash, pruritus, or acne-like eruptions Flushing temporary redness of the skin Chromaturia red-coloured urine (harmless but can cause concern if unexpected) Less common but more serious reactions include: Hypersensitivity reactions ranging from mild urticaria to anaphylaxis (rare but potentially life-threatening) Hypokalaemia particularly during initial treatment when rapid cell production occurs [5] [16] Temporary changes in blood counts during correction of deficiency Interference with laboratory tests primarily with high-dose IV hydroxocobalamin used for cyanide poisoning, not typically with standard 1mg IM replacement doses Cautions and contraindications: Hypersensitivity to cobalt or vitamin B12 Cyanocobalamin should be avoided in Leber's hereditary optic neuropathy [2] [17] Chloramphenicol may reduce the haematological response to B12 therapy Patients receiving B12 injections outside clinical necessity face unnecessary risks without proven benefit

For individuals receiving B12 injections for severe deficiency, there have been isolated reports of hypokalaemia (low potassium) during initial treatment, as rapid cell production consumes potassium