This isn't just a side effect
Bibcode:1994ApEnM..60.1495K
Risks While B12 injections are generally considered safe, especially when administered under medical supervision, there are some potential risks and side effects to be aware of: Pain, Redness, or Swelling at the Injection Site: This is the most common side effect and is usually mild and temporary
Myth: "If I take more milligrams, I'll get better results." Fact: Higher doses do not always mean better results
In fact, one study found that peoples bodies absorbed about 49% of a 1-mcg dose of cyanocobalamin, compared to 44% of the same dose of methylcobalamin ( Conversely, another study comparing the two forms reported that about three times as much cyanocobalamin was excreted through urine, indicating that methylcobalamin may be retained better within your body ( However, some research suggests that differences in bioavailability between the two forms may be insignificant and that absorption could be influenced by factors such as age and genetics ( Unfortunately, recent research directly comparing these two forms of vitamin B12 is limited