A B12 injections effect can last anywhere from a couple of weeks to a few months, and the difference comes down to why you are deficient, how well your body holds on to B12, and the dose and schedule you are on
(However, note that when injecting intramuscularly or subcutaneously, any trace preservative is generally well tolerated
10.1016/j.ejphar.2011.05.038 50 IlicS.DrmicD.ZarkovicK.KolencD.CoricM.BrcicL.et al (2010)
While some users report short-term benefits, the absence of extensive, well-conducted studies prevents us from fully understanding potential long-term risks
Unfortunately, only 23.5% of those who were hospitalized in the U.S
Dosage reported ranges (overview) Community and commercial sources commonly describe oral doses of roughly 50150 mg per day, typically in capsule form