Hi Kerrilyn, I can only conjecture on this. Mb12 affects the autonomic nervous system that controls contraction and dilation of capillaries. The "signal" comes across stronger with mb12 and while the nerves are still damaged, has some effects. The heat may be provoking the dilation response and it is stronger because of mb12. This may be an explanation. I don't really know. I had all sorts of short term responses that went away in a few months.