I tried activated Quercetin which inlcuded bromelain, vit c and magnesium citrate. It seems to increase the symptoms somehow. I was thinking possibly because Quercetin can increase Dopamine which he seems to be high in based on symptoms (not positive though). Right now I've been using methionine which seems to be helping. He has tested pretty low normal for this a year ago so I feel he's got a little room to handle it. He's also very low normal homocysteine (has been below normal in the past). Methionine can increase homocysteine for its something to watch. However, methionine can decrease blood histamine and raise serotonin. I do need to run out and get histamine degrading probiotics, thanks for the reminder. These are the 3 I've seen : Probiotics B infantis, B longum, L plantarum. I will check into Lactobacillus as well. Thanks! Also, sometimes I've wondered if vitamin c (which is supposed to breakdown histamine) hypes him up. Have you ever seen this?