These Vitamin B12 Injections are manufactured in our facilities in China, India, and the USA
As for effectiveness, heres a study in which healthy women were randomly assigned to consume 400 g of folic acid, 416 g of methylfolate (the bioequivalent dose of folic acid), and 208 g of methylfolate (half dose)
Its also important to note the cause of skin anesthesia, if known, and any symptoms or complications
Fatigue accompanied by anhedonia, sleep disturbances, or changes in appetite beyond those expected from the medication warrants evaluation for depression, potentially using validated screening tools like the PHQ-9
Because they are not easily cleared, very high intakes can build up and cause toxicity
PMID 25382550