Histamine is an immune system componenet. damaged cells release it and it permeates the skin in an attempt to aid in detoxing, as the toxins move through the skin they cause itching and redness because they are caustic. you don't want to do anything to impede histamine production you want to remove the cause instead.
Methylation methods used by doctors are nonsense. Trying to force your detox pathways open without completely adjusting your mitochondrial chemistry is useless because of the Fluid Genome, Again not treating the cause. Your detox ppathways will open back up once you are detoxed and this takes a while.
The use of ALA and MSM accomplish this as explained here.