Are there any medications or supplements to avoid prior to blood/urine testing for MCAD? How long should we both off of these? My Doctor said 2 days off of my anti-histamine. Secondly, how do we cope during these days before, I am going to go nuts from itching and hives, anything I can do to calm it without affecting results of the test? Am I at a greater risk of anaphylaxis being off my anti-histamine?