can you inject b12 into your stomach Shots at Home: How, Where & How Often to Yourself How to self-inject intramuscular vitamin
Description
Commonly referenced guidance includes: Initial replacement Maintenance For maintenance, the BNF lists adult prophylaxis/maintenance dosing such as 1 mg intramuscularly every 23 months in appropriate cases

Common side effects may include mild pain at the injection site, redness, or swelling

You can, but results will be negligible
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Novel small molecule inhibitors of nicotinamide N-methyltransferase (NNMT)