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) What should you not do after a B12 shot
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"Why Insects Should Be in Your Diet"
Since vitamin B12 is primarily found in animal products, individuals following a plant-based diet may be at risk of deficiency
Understanding these potential effects helps patients make informed decisions about their supplementation regimen and recognise when symptoms warrant medical attention