Thanks for all your replies. It took me a long time deciding which probiotic to try. I chose strains that degrade histamine or that are neutral. I took a small amount today & so far ok. I do eat sauerkraut occ altho it is not supposed to be good for those of us with hypothyroid. looneymom, I have allergen free Pure Encapsulations. The only additive is rice starch & it is vegetarian capsule but I take it out of capsule & sprinkle on food. Katybug, I haven't been tested for mcas but I did have a bad reaction to histamine during allergy testing.