The rate of absorption is slow
The relationship between body weight and optimal dosing has not been established through controlled trials
After getting a B12 shot, you should watch out for these symptoms and see a doctor if you have: Strong pain where you got the shot Some stomach upset Feeling swollen Skin feeling itchy for a while In really rare cases, there might be more serious risks like: A severe allergic reaction called anaphylaxis Fluid build-up in the lungs Heart problems Blood clots in the bodys blood vessels A type of blood cancer, called polycythemia vera
2020 Dec 4;5(1):280
IDEAL FOR: Prevention therapy as well as relieving migraines/headaches, fatigue, effects of illness, allergies, asthma, pain, gastrointestinal ailments, athletic recovery, hangovers, and emotional disorders such as anxiety or depression for parents, travelers, teachers + caregivers exposed to illness
Everything below is compound-level evidence, presented so you can see what is and is not established