Many people on this forum have said that B12 injections made their symptoms worse. Neuropathy became exacerbated. To understand why this happens, we have to go to the synaptic cleft, or the connection between neurons. When a neuron is damaged due to B12, B1, or B6 vitamin deficiencies, the neuron no longer fires a signal. As a result, you may feel numbness in the feet or hands. The neurons in the affected network compensate for this weak or absent signals by increasing the number of neurotransmitter receptors. With more receptors, neurons attempt to restore the signals to normal. When you start B12 (or B-complex) injections, the vitamins start to heal and "awaken" the sluggish or dormant neurons. But with the extra receptors in the neuron connections (synaptic cleft), over-firing occurs. It is necessary to wait for the neurons to down regulate the excess of receptors. In this case, the B12 injections 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.
I saw a video on YouTube where this lady explains her symptoms and how even after her B12 injections, her symptoms continued to get worse. Her name is Nora England and I think her story can be encouraging to many who are starting with the injections.
I was shocked at how similar her symptoms where to mine.
Here is the video below: