The most common side effects are mild and include injection site reactions (redness, slight swelling, or tenderness), mild headaches during the initial days of use, and occasional dizziness or lightheadedness
Giving them more frequently than the established schedule is a form of over-treatment that is not supported by evidence and can strain healthcare resources (nurses time, clinic space, and medication supplies)
We will gather relevant medical information from you, such as your current medical issues, supplements and medications you are taking, previous treatments you have had, your lifestyle habits, and blood lab records
Basically, during metabolism, some proteins and fats are broken down by Vitamin B12 so that they could be converted to energy
medlineplus.gov
These symptoms aren't always due to vitamin B12-deficiency anaemia, but if you have them see your GP. Avoiding vitamin B12 deficiency Experts say adults aged 19 to 64 require around 1.5 micrograms a day of vitamin B12, and you should be able to get this through your diet