For people with cobalt allergy (which is more common among people with nickel allergy) who are also at risk of vitamin B12 deficiency, the "general advice seems to be 'take just enough but not too much,' which isn't too different from dosing advice for all vitamins and drugs" (via ACSH)
Psoriatic Arthritis A type of arthritis that causes joint pain, swelling, and stiffness, often occurring in people with psoriasis
Eur J Neurol 20 , 14451450 (2013)
However, like any medical treatment, they can have some side effects
Whether genetic or environmental, it should be noted that food intake, rates of metabolism levels of exercise, and physical exertion vary from person to person
Whilst extremely rare, anaphylaxis to B12 preparations has been documented