Histamine receptors are most dense on the hippocampus which controls the entire endocrine system. In CFS endocrine system failure is common. So is low stomach acid. Histamine is responsible for increasing stomach acid. Without stomach acid vital nutrients like iron and others cannot be absorbed, causing more hypoxia. Protein is not properly digested, causing more histamine deficiency (histamine being derived from the amino acid found in protein, histidine). There are several implications for this. Inability to convert folic acid to metafolin (Active form) could be causing a histamine deficiency. Copper excess could be causing it. In any event I find my asthmatic symptoms are relieved by supplementing with beta alanine (carnosine molecule attached to histidine), histidine, and niacin (which elevates histamine levels) and is necessary for proper HCL production in the stomach. If you are functionally anemic you may try elevating histamine first so that there is enough stomach acid to digest the iron and the bacteria in the large intestine just don't go crazy off the excess iron (which they love). I found it interesting that the first symptom I've had and still have is asthma. http://www.scribd.com/doc/62194357/The-Plot-Against-Asthma-and-Allergy-Patients Check this book out. The doctor claims to be treating CFS with histamine injections. I don't know where to get histamine injections, so I tried the next best thing with the above bolded supplements. Maybe this will help someone. An overactive immune system could be the result of low stomach acid. And thus leaky gut symptomology contributes to adrenal exhaustion and further endocrine disturbances with infection from undigested food/bacterial overgrowth.