"Analytical approaches for the detection of emerging therapeutics and non-approved drugs in human doping controls." Journal of pharmaceutical and biomedical analysis 101 (2014): 66-83
These symptoms occur due to fluid shift and pressure on the nerves, which usually improve with dose adjustment or taking short breaks after consulting with your healthcare provider
In this case, the B12 shots have started to heal the damaged neurons myelin sheath, but the neural network in which the healed neuron is in, is in a super sensitive state (with extra receptors), so the patient may feel pain or other unpleasant sensations
Each ml contains 3,000 mcg cyanocobalamin
[6] In all cases, a healthcare provider should evaluate patient history for any contraindication before initiating therapy
Whichever you pick, let the certificate of analysis decide, and browse the vendors current lab reports before you buy